Design Of Material Handing System By Dvshirbhate

1

UNIT - I Introduction, Definition of Material Handling, its relationship with Plant Layout. Type of industries, related material handling Equipment. Design of Plant Layout, Site selection for Plant. INTRODUCTION :Material Handling involves the movement of material, manually or mechanically in batches or one item at a time within the Plant. The movement may be horizontal, vertical or combination of horizontal or vertical. Material Handling is concerned with motion, time, quantity and space.

The

Material Handling Institute describes this as follows, (1) First, Material Handling is MOTION. Parts, material and finished products must be moved from store to location. Material Handling is concerned with moving them in the most efficient manner. (2) Second, Material Handling is TIME. Each step in any manufacturing process requires that it supplies are on hand the moment it needs them. Material Handling must assure that no production process or customer need will be hampered by moving material arranged of location too late or too early. (3) Third, Material Handling is QUANTITY. Rate of demand varies between steps in the manufacturing process. Material Handling has the responsibility of being sure that each location continually receive the correct quantity of parts. (4) Fourth, Material Handling is SPACE.

Storage space, both active and

dormant, is a major consideration in any building as space costs money. Space requirement are greatly influenced by the Material Handling flow pattern. Put these four elements together and you have the basics of Material Handling. It should be noted that this element are not treated independently. They must be integrated and there composite performance determines the quality of Material Handling systems. DEFINITION'S OF MATERIAL HANDLING :1) BASIC DEFINITION: Basically Material Handling is the art of implementing movement-economically and safely.

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2 In the classic sense, Material Handling is the act of creating Time and Place utility, as distinct from Manufacturing, which creates form utility. The proper application of Material Handling knowledge will result in the smooth integration of all the process in an enterprise into one efficient Production Machine. 2) BY J.R. BRIGHT: Material Handling is a system designed in order to get the materials. At right place b) at right time c) in right quantity d) in good condition e) at minimum cost. 3) BY HENRY FEYOL : It is a system of auxiliary equipment that improves flow of material which intern reduces stoppage in production machines and thus increases productivity of machine. These equipment are designed in order to supplement the production machines. 4) BY JAMES APPLE : It is that branch of Engineering concerned with development of special Machinery for transporting goods through various manufacturing stages to finished product stage. It is systematic physical movement of material. 5) BY NATIONAL PRODUCTIVITY COUNCIL : It is a system which forms the single factors of movement, transfer, warehousing, in process handling and shipping into one interdependent cycle considering the most economical solution for the respective plant. If we look at the cost for Material Handling formed to a cost circle there are the following cost factors (fig 1) :

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3 The goal, therefore, is to get control over these costs to be able to reduce them with effective Material Handling. Briefly, Material Handling is the moving of materials from the raw stage through Production to ultimate Customer with the least expenditure of time and effort so as to produce maximum Productive Efficiency at the lowest Material Handling cost. PLANT LAYOUT : Plant Layout means the physical arrangement of the various Industrial facilities (equipment, material, manpower, etc.) within the plant. This arrangement includes the spaces needed for material movement, storage, indirect labourers and all other supporting activities or services as well as operating equipment and Personnel. Plant Layout is the basis of industrial activity since it determines the efficiency. Generally what is being achieved is arrangement of work areas and equipment which is the most economical and at the same time safe and satisfying employees. Plant Layout is concerned with the analysis, planning, and design of the physical facilities utilized in the production of goods and services. Material Handling deals with that phase of the operations which involves the movements of the material used in carrying on the activities of the enterprises. No two aspects of industrial activity are more closely related. Actually, Material Handling is a Major part of nearly all Plant Layout work. This close relationship is emphasized in the following definition of Plant Layout : Plant Layout may be defined as planning and integrating the paths of the component parts of a product to obtain the most effective and economical inter relationships between men, equipment and the movement of material from receiving, through fabrication, to the shipment of the finished product. TYPES OF PLANT LAYOUT AND FUNCTION :1) PROCESS LAYOUT OR FUNCTIONAL LAYOUT : It is characterized by keeping similar machine or similar operations at one location (place). In other words, all lathes will be at one place, all milling machine at another and so on, that is machine are to be arranged according to their function. This type of layout is generally employed for industries engaged in job order production and non-repetitive kind of maintenance or manufacturing activities.

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4 Advantages of Process Layout : 1) Better Machine utilization allows lower investment on equipment. 2) It is better to maintain continuity of production in event of (a) Machine breakdown (b) Storage of Raw material (c) Absence of workers 3) It copes up with varying production schedules. 4) It is adopted to a variety of products and to frequent changes in sequence of operations. 2) PRODUCT LAYOUT OR LINE TYPE LAYOUT : It implies that various operations on a product are performed in a sequence and the machine are placed along the product flow line, i.e., machines are arranged in the sequence in which a given product will be operated upon. This type of layout is preferred for continuous production, i.e. involving a continuous flow of in-process material towards the finishing product stage. Advantages of Product Layout : 1) Less Handling of Material. 2) Less material in process allows lower investment in materials. 3) More effective use of labour (a) through greater job specialization (b) through ease of training (c) through wider of labour supply 4) Easier control (a) of production allows less paper work. (b) over workers allows easier supervision 3) COMBINATION LAYOUT : A combination of process and product layout combines the advantages of the both types of layouts. A combination layout is possible where an item is being made in different shape and sizes. In such cases machinery is arranged in a Process Layout but the process grouping is than arranged in a sequence to manufacture various types and sizes of product. The point to note here is that, no matter the product varies in size and type, the sequence of operations remain same or similar. DOMHS

5 4) FIXED POSITION LAYOUT : In other types of Layouts discussed earlier, the product moves past stationary Production Equipment, whereas in these case the reverse applies ; men and equipment are moved to the material, which remains at one place and the product is completed at that place where the material lies. For e.g., aircraft manufacture, ship building, big pressure vessel fabrication. 5) GROUP OR CELL LAYOUT In a group or Cell Layout, the layout design is in not according to functional characteristics of machine, but rather by group of different machines (called Cells) that are necessary for the production of families of parts. PRINCIPLES OF PLANT LAYOUT : A few sound principle of Plant Layout are, 1) INTEGRATION: It

means

the

integration

of

production

center

facility

like workers,

machinery, raw material, etc. in a logical and balanced manner. 2) MINIMUM MOVEMENTS AND MATERIAL HANDLING The number of movements of workers and materials should be minimized. 3) SMOOTH AND CONTINUOUS FLOW Bottlenecks, congestion points, and back tracking should be removed by proper line balancing technique. 4) CUBIC SPACE UTILIZATION Beside using the f1oor space of a room, if the ceiling height is also utilised, more materials can be accommodated in the same room. Boxes or bags containing raw material or goods can be stacked one above the other to store more items in the same room. Overhead Material Handling Equipment's save a lot of valuable floor space. 5) SAFE AND IMPROVED ENVIRONMENT: Working places-safe, well ventilated & free from dust, noise, fumes, & other hazardous conditions decidedly increase the operating efficiency of the workers & improve their morale. All this leads to satisfaction amongst the workers & thus better employer employee relations.

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6 6) FLEXIBILITY: In automotive

and

other

industries

where

models

of

products change

after some time, it is better to permit all possible flexibility in the layout. The machinery is arranged in such a way that the changes in the production processes can be achieved at the least cost to disturbance. PROCEDURE FOR DESIGN OF PLANT LAYOUT : The ideal procedure for a plant

layout,

is to build

the layout around the

productive process and then design the building around the layout. This may not be possible always, because the plant building may already be existing or the shape of plant site may not permit the construction of building to house the productive process, etc. Ultimately, one has to strike to balance between the two approaches. However various procedural steps involved in plant layout have been listed below a. Accumulate basic data, b. Analyse and coordinate basic data, c. Decide the Equipment and Machinery required. d. Select the material handling system. e. Sketch plan of plot for making factory building, f. Determine a general flow pattern, g. Design the individual work stations, h. Assemble the individual layout into the total layout, i. Calculate the storage space required. j. Make flow diagram for workstations and allocate them to areas on plot plan, k. Plan and locate service areas, l. Make master layout, m. Check final layout, and n. Install the approved layout. Interrelationship Between Material handling and plant layout Material handling and Plant Layout are closely interrelated, and a

reciprocal

relationship exists between the two. An effective layout involves least Material Handling and DOMHS

7 less costly material handling equipment. It permits, material handling without any loss of time, with minimum delays and least back tracking. The total number of movements and the distances moved in one movements are also considerably reduced in a properly designed plant layout. In a poorly planned layout, the aisle's s/sub aisle's widths or ceiling heights may not be sufficient to accommodate efficient material handling equipment; even if used somehow or rather, the back tracking or duplication of material movements may not permit the material handling system to be economical. On the other hand, an efficient material handling system helps building an effective plant layout around itself. Various departments are located such that the material handling is minimised. Space requirements are considerably reduced. Material movements are much faster and more economical. Bottlenecks and points of congestion are removed. Machines and workers do not remain idle due to lack of material. Production line flow becomes smooth. The place of material handling in industry It has been said that for manufacturing activity of any kind, whether it is a single machine or a group of machine or an entire plant, it is possible to identify three basic function which define the total activity. The functions are work performing, handling, and control. This function is shown in figure 2.

Fig 2. Three basic function of any manufacturing activity FUNCTIONS OF MATERIAL HANDLING Material handling embraces two functions namely; 1) Moving It includes movement between machines or workstations, between department, between buildings, the loading and unloading of carrier's, as well as much of more handling done at work place. DOMHS

8 2) Storage: It includes storage of material and tools and supplies between and around all of the above location, including finishing good, warehousing, and the other storage related activities that lie between the producer and consumer. 3) Selection a. To choose production machinery and assist in plant layout so as to eliminate as far as possible the need of material handling; and b. To choose most appropriate material handling equipment which is safe and can fulfill material handling requirement at the minimum possible overall cost. OBJECTIVES OF MATERIAL HANDLING All tangible and intangible benefits can be reduced to four major objectives. The application of material handling methods and equipment to be of greatest benefits should be governed by the following; 1) REDUCED COSTS: Cost-Reduction programs has two broad goals; either to reduce the cost of Material Handling or to reduce total production cost; by improved handling procedures. latter concept

The

sometimes means increasing handling costs in order to bring about a

net reduction in total manufacturing costs. Ways in which cost reductions are realized through improved material handling are; a. Reducing material handling labour. b. Reducing the Material handling work done by direct labour. High-skill and high-cost labour should not be assigned low-skill and low-cost labour. c. Reducing indirect labour associated with material handling activities, such as shipping, production control personnel, inspectors, etc. d. Reducing waste and damaged materials through more careful handling. e. Reducing paper work

and

associated clerical

help

through handling systems that

minimizes control requirements. f. Reducing the amount of material in the system by faster through-put and less in-process storage.

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9 g. Reducing the amount of subsidiary materials such as packaging materials and other protective devices such as trays, racks and special containers. 2) INCREASED CAPACITY Material handling improvements can increase capacity in the following ways, a) Better space utilization Modern storage systems, make use of "AIR RIGHTS" by means of racks or containers that stack upon each other when full and nest completely when empty, e.g. Handling systems, particularly cranes and conveyor can operate in unused space above production activities. They can be arranged to operate outside buildings in unnecessary stairways, through underground passage-ways, or other unusable space. This can release prime space for production and storage. The net result is a great increase in space utilization and handling efficiency. b) Improving the layout to reduce travel or excessive waste of spaces By analysing the flow of materials between operations, the volume involved in the flow paths, and the timing of material movement, it is usually possible to reduce travel time and space

needs. Rearranging equipment and providing handling systems that reduces the distance

material must travel are usual practices. c) Higher equipment utilization Many pieces of expensive production equipment do not operate at their potential capacity because are limited by the rate at which materials are supplied to, or removed from, the equipment or the work area. A proper handling system, or efficient control of an existing handling system can greatly increase production equipment utilization. d) Faster loading and discharge of common carriers: The adaptation of portable conveyor systems & cranes to the loading of motor carriers greatly reduces loading time. Thus the transportation unit can spend more time moving and less time sitting the loading dock. This not only lowers operating cost but reduces the number of docks or terminal spaces required, with a corresponding reduction in loading crews (workers) and of supervision. 3) IMPROVED WORKING CONDITION a) Safety to men, materials and associate equipment: DOMHS

10 These may be enhanced by a proper material handling system. Insurance cost. Accident cost, lost time associated with accidents, etc. are all reduced by proper material handling. Material and equipment damage are also greatly reduced. b) Easier jobs When heavy objects must be handled, the rate of output may be significantly affected by the physical ability and condition of the operators. Moreover, heavy work can only be done by men, and often only by young men. Many handling system have been justified in part, by the fact that they have taken the high effort out of the task, resulting in a steadier flow of work throughout the day and in higher production. It also may mean lower employee turnover, less training on replacement workers and better morale in the work force. c) Lighter Work If the work is physically lighter, it may be possible to use operators at different job classification i.e. At lower wage rate. d) Fool proof operation : In some activities it is also too easy for an operator to become confused and to direct material to a wrong location, to use the wrong amount, to mishandle or damage materials, or to otherwise disrupt production operation. Handling systems are sometimes installed to insure that such errors will not happened. In the mixing of fertilizers, foods, and other bulk products that are formulated to order, this may be very attractive benefit. 4) IMPROVED SALABILITY OF PRODUCTS Handling systems often enhance the value of a product to the customer. The adaptation of such handling system may make the difference in the customer's decision to use one vendor instead of another. This may be accomplished by the following means. a) Speed of service: If

the

handling

procedure

can

provide

goods

or

materials promptly,

accordingly to the customer's desire, or with a significant time advantage over competitors, it may be the prime reason that business is obtained or retained. b) Helping customers cut costs The development of the unit load has enabled vendors to help customer cut there of cost since they need not handle individual items or undertake the expense of palletizing on their own docks. DOMHS

11 The reduction in packaging or packing materials and their cost is some times obtained through unit load

techniques. This may enable the vendor to cut his cost to the

customer. Also, the use of materials by the purchaser may be simplified by proper unit load design thereby reducing the cost of unpacking and disposing of the packaging material. Unitizing by the vendor may be done at the end of his assembly lines, or other final operations. C) Sales value of an outstanding installation : While it might be hard to prove that a handling system is justified in promotional value alone, a tremendous amount of publicity can accrue to a truly outstanding system. Several managers have been heard to argue vigorously that by taking prospective customers through their new factories, the visitors have become so impressed that an order was obtained because of the impression of efficiency, quality and service conveyed by the installation. An outstanding plant is admired by employees as well as customers. To say again in brief, the primary objectives are; 1. To save money 2. To save time 3. To save men LIMITATIONS AND NEGATIVE ASPECTS OF MATERIAL HANDLING SYSTEMS It is bad engineering and worse management practice to look only at benefits and to ignore limitations. Handling systems, at times, have consequences that may be distinctly negative. These too, should be evaluated before the changes are

adopted.

Some such possible

disadvantages are 1) Additional capital investment : It must be verified that the cost of the handling system is more attractively invested in the system under consideration than in any other part of the business. It should be assured that the gains expected are not based upon a more mechanized system v/s present practice, but rather the proposed new system v/s the best version of present practice. 2) Loss of flexibility Proposed system must be flexible enough to be economically and quickly adopted to the likely range of changes in the product or production techniques. If not, change over cost and

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12 time loss must be included in the evaluation, or it must be shown that the investment will be satisfactorily recovered before the proposed handling system will require modification. 3) Vulnerability to downtime; Since a handling system is a composite of mechanical and electrical machinery and controls, it must be recognised that it may break down at any times. What happens than how long will it take to get back to service and what will be done when repairs are being made. If this is serious-, the handling system must be re-design to provide for better reliability, for alternate handling techniques in event of breakdown or for in-process- storage that can feed subsequent operations while be system is being repaired. All of these can result in additional costs that must be charged against the handling system. 4) Maintenance If it is planned to install additional handling mechanization, almost surely it will be necessary to take on more maintenance. This may mean the addition of new maintenance skills, or a provision for obtaining them when needed. It may be that extra pieces of handling equipment should be provided for use during downtime or breakdowns. It may be necessary to plan for periodic overhauls by skilled technicians. It may be necessary to carry a large supply of repairs parts, or a new or enlarged maintenance facility and staff may be required. 5) Auxiliary equipment costs Frequently a new handling system carries with it requirements that involve hidden or unrecognized costs for auxiliary equipment or service, e.g. adopting a fork lift truck means more than taking on the mobile equipment, its power supply, and its maintenance. The point of identifying this drawbacks is neither to discourage nor disparage the adaptation of modern handling methods, but to emphasize that a careful balance of the total benefits and limitations is required before wise decisions can be reached. OBJECTIVES OF PLANT LAYOUT AND MATERIAL HANDLING In much the same way that the scope of both plant layout and material handling are closely interrelated, so also are their objectives. Indicated below are some of the objectives of plant layout. Under each are listed some objectives of material handling associated with each plant layout objectives. 1) Facilitate the manufacturing process DOMHS

13 a) Efficient flow of materials. b) Minimum of production bottlenecks. c) Quicker delivery to customers. d) Better facility for maintenance, inspection, etc. 2) Minimize material handling e) Larger unit loads. f) Less damaged materials. g) Better control of material. 3) Maintain flexibility of arrangement and operation, h) Flexibility of handling methods and equipment. i) Coordinated material handling system. j) Material handling planned for expansion. 4) Maintain high turnover of work in process. k) Shorter production time cycles. l) Constant rate of production. m) Avoidance of production delays. 5) Hold down investment in equipment. n) Less idle time per machine. o) Reduced handling between operation. 6) Make economical use of floor area p) Better space utilization. q) Higher production per square foot per employee. r) Use of material handling equipment not requiring fixed floor space. s) Less congestion and better housekeeping. 7) Promote efficient utilization of manpower t) minimize manual handling. u) Make effective use of containers. v) Lees supervision and indirect labour. 8) Provide for employee convenience safety and comfort. w) Safer working conditions. x) Less fatigue. DOMHS

14 y) Improved personal comfort. z) Upgrading of employees. z) Improved worker morale. SITE SELECTION FOR PLANT A plant is a place, where men, material, equipment, machinery, etc. are brought together for manufacturing products. The problem of plant- location arises when starting a new concern or during the expansion of the existing plant. Plant location means deciding a suitable location, area, place, etc., where the plant or factory will start functioning. Plant location involves two major activities. First, to select a proper geographic region and second, selecting a specific site within the region. Plant location plays a major role in the design of a production system as it determines the cost of (a) obtaining raw material (b) processing raw material to finished goods; (c) dispatching finished goods to customers. The following factors are taken into consideration in the selection of site for plant layout; 1. Availability of land and costs Large amount of land is required for locating a plant, therefore land is selected taking into consideration economy and other facilities such as presence of related industries, future expansion, Housing facility, Taxes, security, existence of school, hospitals, banks, postoffices. 2. Availability of raw material Availability of raw material

is

to

he

looked

into particularly when raw

material are bulky and difficult and expensive to transport, plant must be located close to the source of raw material, it will reduce the cost of transporting raw material. 3. Transport facility A lot of money is spent both in transporting raw material and the finished goods. Depending upon the size of raw material and finished goods, a suitable method of transportation like roads, rail, water or air is selected and accordingly the plant location is decided. Transport facility for the labour to come to the factory are also to be considered.

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15 4. Nearness to the market It reduces the cost of transportation as well as the chances of product getting damaged

the

finished

and spoiled during transportation.

5. Availability of skilled labour Labour is one of the primary tools for transforming material into products. Hence, existing of good training facilities which can be a source of ski1ed labour is a factor to considered.

Further

to attract skilled labour other facilities like housing,

be

transport,

education, and public health are necessary and hence form an important aspect of plant location. 6. Availability of water Water is used for processing, as in paper and chemical industries, and is also required for drinking and sanitary purpose. Depending plant,

water

should

be

available

upon

the

nature

of

in adequate quantity and should be clean and

pure. 7. Availability of electricity and fuel Electricity is the essential factors for any plant location, therefore it is essential that electric power should be continuously available. Industries like rolling mill are located near source of fue1 to cut down the fuel transportation costs. 8. Climate and environment Some industries requires good

climatic and

atmospheric conditions for

efficient manufacture, like humidity, dust-free environment, etc. This aspect has to be looked into since otherwise it may be essential to provide these facilities artificially and thus increasing cost. 9. Facilities for disposal of effluents: In the case of process industry, disposal of effluents is very important. There should be scope for very efficient disposal of effluents. 10. Municipal regulations: Municipal regulations concerning location of industries have to be carefully looked into. SYMPTOMS OF POOR LAYOUT :The symptoms are, 1) Excessive inprocess materials. DOMHS

16 2) Excessive increase in idle time of men and machine. 3) Increase in maintenance. 4) Congestion in floor space as well as aisles. 5) Increase in breakage's of material and products. 6) Increase in accidents. 7) Increase in handling costs. TYPES OF INDUSTRIES AND RELATED MATERIAL HANDLING EQUIPMENT Material handling in (a) Small industry In small industries mostly manual handling devices are used to move the materials inside the plant. For such purposes, material are moved by unskilled labour from one department to the other in containers carried by them in hands or in tray6, handcarts and in wheel barrows etc. Material inside the shop can be moved by operators themselves while working on different machines till the work on the job is fully completed for that particular shop. (b) Thermal power plant In thermal power plant, the main items to be handled are coal and ash. Coal can be transported from the source of supply to the stock-yard either by rail or road. Then, from the stockyard it is pushed to coal handling plant by trolleys either manually operated or locomotive may be employed. Further from handling plant coal is moved to boiler bunker through a belt conveyor. From bunker coal is fed in the hopper through a belt conveyor, and from hopper it is fed on grate by gravity. Ash is moved at a distant place with belt conveyor. Further bucket elevator raises the ash in hopper where it can be moved outside the plant with the help of hand trolleys or trucks or wagons. It depends on the quantity to be handled. In addition, overhead cranes are almost installed in every plant such as turbine house, boiler house, water treatment. Pump house and repair shop etc. (c) Big automobile repair shop In a big automobile repair shop both manual and mechanical handling devices are used. "Fork Lift truck” is very common for elevating and moving the heavy parts such as complete DOMHS

17 engine assembly, engine block, gearbox, etc. Motor trucks are employed for inter department transporting of heavy components. Overhead cranes are used in machine shop, engine shop, assembly shop & degreasing plant etc. Recovery van may be used for moving breakdown vehicles. (D) Big steel plant In a big steel

plant

almost

all

types

of

handling devices

are employed.

Locomotive is used to carry laddles of molten pig from blast Furnaces to steel shop or to open hearth furnaces. They are used to Pull the hot ingots of steel shop or to open hearth furnaces. They are used to pull the hot ingots of steel of steel shop or to open furnaces,. They are used to pull the hot ingots of steel to rolling mills for Production of various steel sections. They are employed for bringing in Iron

ore and other huge materials. Belt Conveyor is employed to

transport coke oven to blast oven to blast Furnace. Belt conveyor is employed to transport coke from coke oven to Blast oven to blast furnace. Belt conveyor is also used for- Transporting sand in huge casting foundry shop. Roller conveyor is used in rolling; mills- to move the hot Billets of iron along the bed to various processes. Huge cranes are employed to transport machinery and iron ore for storing and processing. Overhead cranes are installed almost in every shop. (e) Cement factory : In dry process of cement manufacture, the various stepwise Processes are (1 ) crushing of raw materials, (2)drying, (5)grinding, (4) Proportinating, (5)pulverizing of raw material, (6) Burning, (7) Cooling and storing the Clinker, (8) Adulteration of related set, (9)reduction of clinker to an impalpable powder, (10)seasoning of cement, (11) bagging. MATERIALS HANDLING EFFICIENCYThe efficiency of material handling could be judged by the following principles: 1. "equipment built for motion should be kept in motion; idle Equipment should be kept inexpensive". 2."continous material movement is most economical" This principle states that materials handling efficiency is Greatest when it approaches a steady flow of materials, in as straight As possible, with minimum interpretations and minimum backtracking and Where movements approach continues rather than intermittent flow. DOMHS

18 It is not; always possible, in practice, to completely achieve The objective of this rule. However, it is the target towards which we Aim our thinking. conveyors systems, both overhead and floor types, are excellent examples of the application of this idea. 3. "materials' handling economy is generally directly proportional to the size of load handled" We all recognise, however, that as the load size increases There is a point reached beyond which it becomes more costly, and less Practical. From this, it is also logical to conclude another important axiom: "there is a definite ideal load size in a given material Handling operation ". 4. "storage space is best measured in terms of cubic content" The "space saving" rule states that equipment should be Selected so as to allow utilisation of cubical space for temporary and Permanent storage. 5. "Material Handling Operations are only as good as the physical layout of the plant will permit" Good layout of machinery, fixed equipment and aisle areas are fundamental to good product handling. Where you are erecting a new building, you have unlimited opportunities to layout the various areas allowing proper aisle widths, sufficient storage areas, and erect your Plant with material movement in mind. 6."standardization of methods, types of equipment and sizes of Equipment is desirable for good material handling efficiency" The most efficient system is generally that which is Simplest. It is not hard to understand why standardization is important, because it permits interchangeability of equipment between Department and plants; it allows stocking of fewer replacement parts; It simplifies employee training in the equipment. In addition, it-enables management to shift equipment from department to department Depending on the production load changes. Another aspect of standardization for the sake of economy in that of choosing equipment That is considered "standard" by the material handling equipment Manufacturer. Standardization does not require that only one size container, for example, is permissible; rather it implies the fewest number possible. In some instances it would be impossible to standardize on one size container especially where a large number of Different parts are handled. Repeat in standardisation does not mean one it means the fewest number. DOMHS

19 7. "The value of equipment

is directly proportional to it's Flexibility"

The greater the variety of uses and applications to which a Piece of equipment can be put, the greater is its flexibility, and the More valuable it becomes from a material handling standpoint. Flexibility in equipment offers the distinct advantage that It is readily adaptable to any unforeseeable changes that comes up from Time to time. in any progressive organization methods and equipment and Constantly in the state of change and improvement. Flexible machinery Takes these changes in stride, and does not have to be scuttled before its

useful life is

completed. 8. " The use of mechanized equipment instead of manpower generally increases efficiency and economy in handling." By the use of mechanized equipment instead of manpower, Efficiency and economy in material handling is obtained. Mechanized equipment must, of course, be able to justify Itself on a rupeeand- basis , like any investment management may Make. Some of the advantage of mechanized equipment are as follows, to both management and labor; ( a) over all safety is increased (b) workers are less fatigue at the end of the day (c) work done by power is generally cheaper (d)larger volume of work handled per operator is accomplished (e)greater speed of handling is obtained, resulting in less Idle time for skilled workers, better production control, a larger volume of goods manufactured and displaced workers put on other jobs in the plant. 9. "Productivity increases as working conditions become safer". Unless mechanized equipment makes s given handling job safer for the plant personnel, it will costlier in the last analysis. In material handing there is an old axiom, "if it is safe, it is not worth it " 10. " The ratio of dead weight to payload must be kept minimum." Mechanical handling equipment which is unencumbered by excessively unnecessary dead weight can perform at top efficiency. For example, an aluminium conveyor is now being substituted in many instances for heavier metal (steel) conveyors where operations require moving the handling conveyor. Another good example is the reduction in weight of DOMHS

20 highway trailers and unit load containers, pallets and skids to eliminate the necessity for hauling excess weight. 11. " The most economical motive force is gravity" One of industry's highest priced items is the cost of power to run its processes. Therefore, when nature's free, bountiful supply of gravitational pull can be put to use the very essence of economy is Practiced. REVIEW QUESTION :.Q. No.l : Give any two definition's of material handling? Q.No.2 : What are the objective of material handling? Give two Definition of material handling supported by standard organization? Q.No.3: define material handling system. Explain how it increases Productivity? Q.No.4: Material handling does' not add value to a product, it usually adds a significant element of cost. Justify the statement. Q.No.5: What are the different factors affecting the plant Location? Q..No.6: How the plant layout affect the selection of material Handling system? Q.No.7: What do you understand by flexibility of plant layout? Q-No.8: Explain the various principle of plant layout for material Handling? Q. No. 9: what type of plant layout would you suggest for :(i) hospital (ii) milk industry (iii) pharmaceutical industry . Q.No. 10: What do you understand by flexibility of layout? Q.No. 11. What are different types of industries? Give related Material handling equipment's for each type? Q.No.12. (a) Discuss the selection of material handling system for foundry shop ? Q.No.13. (b) What are factors to be considered while planning a lay out of a plant ? Q.No.14. (a) How does selection of site affect the plant layout ? Explain. (b) What is relationship between plant layout and material handling? Q.No.15. (a) What do you understand by flexibility of a plant layout ? Explain with the help of Suitable example. DOMHS

21 (b) Explain in brief a factor affecting in selection of plant location ? Q.No.16. (a) Discuss how good layout and efficient material handling system creates space utility. (b) What type of layout would you suggest for automobile industry ? Justify your answer. Q.No.17. (a) What are objectives of material handling ? Give two definition of material handling supported by standard organization ? (b) What type of plant layout would you suggest for Hospitals? (c) Discuss different types of plant layouts and function ? Q.No.18. (a) What are advantages and disadvantages of urban site ? (b) Explain process layout with its advantages & disadvantages? Q.No.19. (a) Suggest a suitable layout for following industries and justify your answer (i)

Thermal power plant.

(ii)

Sugar Industry.

(b) Define material handling system. Explain how it affect (increases) productivity ? (c) How plant layout affect the selection of material handling system ? Q.No.20. (a) Material handling does not add value to a product it usually adds a significant element of cost. Justify the statement ? (b) Give any two definition of material handling system ? Q.No.21. (a) Explain various principles of plant layout for material handling system ? (b) Classify and explain various material handling system ? Q.No.22. (a) Discuss need and importance of material handling systems in industry by means of suitable example ? (b) What is plant layout ? Discuss design procedure of plant layout for material handling system ? Q.No.23. (a) What are different types of industries ? Discuss one example and its material handling system ? (b) What are proper selection of site for plant ? What factor consider for proper site selection ? Q.No.24. (a) Efficient material handling is the heart of production activity ? Explain. (b) What are various plant layouts ? Explain in details ? Q.No.25. (a) Material handling system is a function of DOMHS

22 (1) SPACE (2) TIME (3) QUANTITY (b) Suggest suitable layout for the following industries & justify your answer. (i)

Ship building industry.

(ii)

Pharmacutical industry.

(iii)

Bottling plant for cold drink.

Q.No.26. (a) Write the advantages and disadvantages of rural site ? (b) Explain line layout with its advantages & disadvantages. (c) Explain the principle of cubic space utilization with suitable example ?

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DOMHS

23

UNIT II Principles of Mechanical Handling, Types of Material Handling Equipment and their field of applications. Selection and Specification of Equipment's. SCREW CONVEYOR :and

field

of

Introduction , Calculation of H.P. of Motor used , Characteristics

Application

of

Screw

Conveyor , Determination of Application of Screw

conveyor, Salient Dimensions and Power Requirement. PRINCIPLES OF MATERIAL HANDLING :The

principle

presented

here

represent

an

accumulation

of experience

equivalent to untold years of practice. They are adapted from those stated in the literature, with certain changes made for clarification and with several new one added to round out the coverage of the field. In reviewing the principles it will be found that nearly every one applies to several aspects of Material Handling and aids in accomplishing one or more objectives. In

presenting the principle's, each

is

stated

and

briefly described. Next,

suggestions for putting the principle into used are spelled out- often in explicit details - to facilitate their prompt convenient application. Then , at the end of the presentation of the principles, some general suggestion are given on their use in analyzing and solving Material Handling problems. 1. PLANNING PRINCIPLE :STATEMENT: All Handling activities should be planned. DESCRIPTION: If there is one principle on which all should agree, it is that Handling activities should be planned, and not left to chance. Remember , Handling may account for 25 to 80 percent of all the productive activity. Management most certainly deserves to have this sizable portion of total activity planned - not left to chance. SUGGESTIONS FOR CARRYING OUT THE PLANNING PRINCIPLE : a) Avoid placing material directly on the floor, without a pallet or other support underneath. b) Assure adequate storage space at the workplace for the proper amount of material , both ahead of

and

following the operation being planned.

c) Plan to use the same container throughout the system ; avoid frequent changes of containers. d) Consider floor Load capacities , ceiling heights, truss capacities , column spacing , etc. DOMHS

24 e) Comp1y with current a.isle width , or alter if necessary and practicable. f) Provide necessary clearances in and around each work place - for proper handling of materials and for maneuvering handling equipment. g) Arrange for instruction for each operator in the correct method. h) Plan for correct location of material supply and disposal in work in work area. i) Provide adequate means for scheduled scrap removal. j) Plan for productive operations and inspections to be done during material movement. k) Combine operation to eliminate intermediate handlings. l) Do make judicious use of Manual Handling. m) Plan to minimize

walking.

n) Apply the principle of Motion Economy 2 .SYSTEMS PRINCIPLE :STATEMENT: Plan a system integrating as many Handling activities as is possible

and

coordinating the full scope of operations (receiving , storage , production, inspection packaging, warehousing, shipping, and transportation.) DESCRIPTIONS Each Handling activity should be considered a portion of the whole Handling system, and planned as an integral part of the system. SUGGESTION FOR CARRYING OUT THE SYSTEMS PRINCIPLE : a) Consider the entire scope of the handling activity, i.e., beyond the area under immediate consideration. b ) Plan flow between work areas. c) Integrate operations into the handling system, such as : processing , inspect ion , packaging , etc d) Arrange for alternative Handling Methods - in case of emergency. e) Move material directly to production whenever practical, rather then an intermediate storage area- to avoid re-handling. f) Work closely with suppliers, customers and carriers. g) Be aware of future requirement changes in product, process, volume, etc. - and allow for necessary flexibility. DOMHS

25 3. MATERIAL-FLOW PRINCIPLE :STATEMENT: Plan an operation sequence and equipment arrangement to optimize material flow. DESCRIPTION : As has been previously suggested. Material Handling and Plant Layout

are

intimately interrelated. The Material-flow pattern is actually the backbone of most production facilities, and one of the first steps in Planning a Material Handling systems is the design of the Material— flow pattern. This may be largely determined by operation sequence , which in turn will determine the pattern of equipment arrangement. SUGGESTION FOR CARRYING OUT THE MATERIAL PLOW PRINCIPLE : a ) Avoid crowded conditions. b ) Eliminate obstacles from Material flow. c) Carefully observe building and carrier restrictions. d) Plan movement in direct path.(Avoid backtracking, zig-zag flow, crooked paths . e) Arrange for alternate path, in case of difficulty. i) Be aware of cross traffic and take necessary precautions. Avoid traffic Jams. g) Keep related work areas close together. h) Use Product-type layout when possible i) Plan proper location of subassembly and feeder lines. j) Comb inc operations to eliminate handling between times. k)Plan for definite pick up and delivery locations. l)Minimize moves between Floors, Buildings. m)Process Heavy, bulky materials close to receiving n) Move the greatest bulk and/or weight the least distance. 4.SIMPLIFICATION PRINCIPLE :STATEMENT: Reduce, combine, or eliminate unnecessary movements and /or equipment . DESCRIPTIONS : Simplification is one of the by-words of efficiency,

motion economy, and

many other aspects of industrial operation. .It should likewise be a goal

in Material

DOMHS

26 Handling. As used here, it implies, primarily, the reduction or elimination of moves as well as the elimination or reduction of equipment that is not being properly utilized. SUGGESTIONS FOR CARRYING OUT THE SIMPLIFICATION PRINCIPLES : a) Apply the principle of motion economy b) Reduce or eliminate long or complicated Moves. c) Plan direct moves. d) Deliver materials to correct location (spot) the first time» e) Avoid unnecessary Handling. f) EIiminate re-handling . g) Plan to use materials out of original container. h)Minimise number of moves per process. i ) Minimize walking. j)Avoid use of variety of equipment types and / or makes. k )Provide proper number of containers. l) Plan for adequate equipment capacity. m) Do not mechanize for the sake of mechanization. 5 .GRAVITY PRINCIPLE :STATEMENT: Utilise gravity to move material whenever practicable. DESCRIPTION: This is certainly a very obvious principle- but one that is all

too frequently

overlooked because of its simplicity. Many material moves can be made efficiently by proper application of the Law of gravity. SUGGESTIONS FOR CARRYING OUT THE GRAVITY PRINCIPLES : a) Use Roller or wheel conveyors, slides chutes, etc., between operations. b)Use ramps between varying work or floor levels. c) Sloping floors (slight) can be utilised where considerable hand truck movement is in one direction. d) Use chutes to connect conveyors at different levels. e)Use spiral chutes to connect conveyors Between floors.

DOMHS

27 6.SPACE UTILIZATION PRINCIPLE :STATEMENT: Make optimum utilization of building cube. DESCRIPTION : Factory and warehouse space are expensive. Therefore, wasted space is wasted money. Inherent in this principle is that both square feet and cubic feet are to be given consideration. One square foot contains as many cubic feet as "clear" height will permit items to be stacked. SUGGESTION FOR CARRYING OUT THE SPACE UTILIZATION PRINCIPLE : a) Move equipment and operations closer together (not too close) b) Eliminate or condense "temporary" storage piles of materials c) Stack material to use full cube available. d) Use racks to permit higher stacking. e) Use stacking containers to permit stacking without racks. f) Analyze space utilization to "find" additional square or cubic feet. g) Check on economic order quantities and economic lot sizes for possibilities of reducing amount of material required on hand. h) Clean out storage areas and dispose of obsolete or useless materials. i) Use narrow-aisle handling equipment to permit reduction of aisle widths. j) Use Handling equipment not requiring fixed floor space , i.e., mobile or overhead Equipment. k ) Don't pile materials directly on floor - use pallets, skids , etc., to permit stacking. l) Consider reinforcing floors to permit heavier floor loads and stacking to greater heights. m) Use collapsible container to save space required by empties. n) Consider possibility of nesting parts products, containers. o) Review possibility of increasing inventory turnover. p) Design Pallets etc. to effectively utilize space between columns. 7. UNIT SIZE PRINCIPLE :STATEMENT : Increase quantity, size, weight of load handled.

DOMHS

28 DESCRIPTION : Wherever practical, individual items should gathered and made up into loads. SUGGESTIONS FOR CARRYING OUT THE UNIT SIZE PRINCIPLE : a) Examine every move of one item for possibility of making up unit loads. b) Purchase materials in unit loads. c) Work with vendors towards design of larger unit loads. d) Use containers to consolidate items. e) Use uniform, standardized containers. f) Design pallet pattern to efficiently utilize pallets and storage space. g) Design load size to make optimum use of handling equipment. 8. SEFELY PRINCIPLE :STATEMENT : Provide for safe handling methods and equipment. DESCRIPTION : It should be obvious that all handling activities in operations or being planned should be safe, since an objective of material handling is to improve working conditions by providing safer work situations. A high proportion of all industrial accidents is in the material handling aspects of the production activity. GENERAL CAUSES OF INDUSTRIAL ACCIDENTS : I) Unsafe Conditions, Environmental Causes. a) Inadequate guarding ( of Conveyors, Trucks, etc ) b) Unguarded (equipment.) c) Defective condition (of equipment ). d) Hazardous arrangement (stacks of material, pallet loads, arrangement of trucks, etc._ II) Unsafe Acts of Persons. a) Operating without authority ( trucks, etc.) b) Operating at unsafe speed. c) Making safety devices inoperative (governors, etc.) d) Using unsafe equipment (needing repairs) DOMHS

29 e) Unsafe loading (machines, conveyors, cranes, trucks, etc.) f) Taking unsafe position or posture (in stacking, in trucks, etc) g) Working on moving equipment (trucks, conveyors, etc.) III) Unsafe Personal Causes a ) Improper attitude (taking chances, disregarding instructions) b) Lack of knowledge (poor instructions, new man, unskilled) SUGGESTION FOR CARRYING OUT THE SAFETY PRINCIPLES a) Install adequate guards and safety devices on handling equipment. b) Keep handling equipment in good operating condition . c) Furnish mechanical handling equipment for difficult, hard, hazardous handling activities and to handle dangerous materials. d) Do not permit handling equipment or devices to be overload or operated over rated capacity. e ) Keep aisles clear and uncluttered . f ) Install adequate lighting. g) Maintain floor in good condition. h) Avoid crowded conditions. i ) Provide good house-keeping. j ) Stacks material carefully. k) Be sure operation are properly instructed in method and / or use of equipment. l) Provide mechanized part feeding and removal devices, m) Plan for removal of undesirable dust fumes, smoke, etc. n) Isolate inherently dangerous equipment, operations etc. o ) Allow Liberal factor of safety. 9 .MECHANISATION/AUTOMATION PRINCIPLE :STATEMENT: Use mechanized or handling equipment when practicab1e . DESCRIPTION: Used judiciously, mechanized or automated handling devices and equipment can be of extreme value in increasing material handling efficiency. However, handling operations

DOMHS

30 should not be mechanized for the sake of ,mechanization alone, nor should they be over mechanized in terms of the function to be performed. SUGGESTION FOR CARRYING OUT THE MECHANIZATION/AUTOMATION PRINCIPLE :

a) Consider use of mechanization for : i) Large quantities or volume of materials ii ) Frequent , repetitive moves, even though short iii ) Long moves iv) High - effort , hazardous, difficult moves. v ) Two - man lifting/moving tasks. vi) Replacing excess manual handling vii) Feeding and removing materials from machine viii) Moving heavy containers. ix ) Handling and done by direct labour . x ) Scrap removal . xi) Reducing

Handling

time.

b) Do not over mechanize. c) Design or select containers suitable for Mechanical Handling. d) Use equipment that is self controlled and self programmed when practicable . e) Consider mechanization of people flow and equipment movement as well as material movement. f) Mechanize communication to facilitate material movement. g) Utilize automatic couplings, switches transfer, etc. h) Move heavy Jigs, Fixtures, Tools, etc by mechanical means. 10. EQUIPMENT SELECTION PRINCIPLE :STATEMENT : In selecting Handling equipment, consider all aspects of the MATERIAL to be handled, the MOVE to be made, and the METHOD(S) to be utilized. DESCRIPTION : This principle is primarily a reminder to be extremely careful in selecting & specifying handling equipment by being sure that al1 phases of the problem are thoroughly analyzed. DOMHS

31 SUGGESTIONS FOR CARRYING OUT THE EQUIPMENT SELECTION PRINCIPLE : a) Select versatile equipment to carry out a variety of tasks and adjust to changing conditions. b) Select standardized equipment to avoid a multiplicity of makes and models - and to minimise inventory of repair parts. c) Prove that the move is necessary. d) Compare Cost on the basis of dollars per unit handled, e) Consider indirect or intangible factors in justifying investments. 11. STANDARDISAT I ON PRINCIPLE :STATEMENT: Standardize methods as well as types and sizes of Handling Equipment. DESCRIPTION : The Material Handling Engineer should constantly on alert for new developments which may replace current methods or equipment. Nor does Standardization means only one type of equipment must be used.

Any attempt at Standardization should be preceded by a

careful analysis. This will assure that the best have been determined , and that the wrong methods, etc., is not standardised inadvertently ,by a failure to make a through investigation. SUGGESTION FOR CARRYING OUT THE STANDARDIZATION PRINCIPLE : a) Adhere to standard sizes of the container, etc. b) Purchase "Standard" types of equipment. c)Purchase "Standard" sizes of equipment. d) Record

standardized methods .

e)Make dock height s. 'standard dimension f)Design new buildings to accommodate pallets,, containers, equipment. g) Keep a manual of standardized methods. 12.FLEXIBILITY PRINCIPLE :STATEMENT: Use methods and equipment that can perform a variety of tasks and application.

DOMHS

32 DESCRIPTION : Equipment that can perform a wide range of handling tasks and which has a variety of uses and application can often be more fully utilized than single purpose, specialized units. Since industry requirements are subject to frequent change, flexibility should be carefully considered as an important characteristics of any Handling Equipments. SUGGESTION FOR CARRYING OUT THE FLEXIBILITY PRINCIPLE : a) Buy flexible equipment -lift trucks, roller and wheel conveyor etc:, b ) Specify adjustable speed drives. c) Make use of attachment and accessories (for lift Trucks, etc.) d) Use gasoline-powered equipment. e) Use four way pallets, skids, containers f) Utilize trucks, etc. (mobile) in favour of conveyors (which may be fixed). g) Carefully weigh use of special purpose equipment. h) Consider adjustable racks. 13. DEAD-WEIGHT PRINCIPLE :STATEMENT : Reduce the ratio of mobile equipment dead— weight to pay load. DESCRIPTION: Excess weight of mobile equipment not only costs more money, but may require additional power and be slower to operate. It is therefore unwise in invest in a heavier— weight equipment than is required by the task to be performed. SUGGESTIONS FOR CARRYING OUT THE DEAD-WEIGHT PRINCIPLE : a) Portable conveyors, dock boards, etc: should be made of lightweight aluminium, magnesium, etc. b ) Use lightweight pallets, skids, containers. c) Purchase aluminium trailers to reduce tare weight. d) Select lightweight equipment for high loads. e) Use " walkie " type trucks (v/s counterbalanced, for elevator servicing.) f) Consider expendable materials for pallets, skids, and containers.

DOMHS

33 14.MOTION PRINCIPLE :STATEMENT: Equipment designed to transport materials should be kept in motion. DESCRIPTION: This Principle implies; that mobile equipment should be keep moving

i.e.,

performing the function for which it was designed. It should not be tied up for unduly long periods of time for loading an unloading. SUBGESTIONS FOR CARRYINB OUT THE MOTION PRINCIPLE :a) Plan to reduce load/unload time to decrease turn-around time. b) Use mechanized loading and unloading equipment. c) Maintain equipment properly to minimize down time. d) Use self-loading equipment- lift trucks, straddle carriers, etc. e) Consider 2-way radio on vehicles to permit quicker stacking. f) Plan return loads for equipment. g) Return mobile equipment promptly for re-use. h) Study carefully use of load-carrier and platform-type trucks where carrying devices are attached to motive unit. i) Plan to haul loads, rather than carry them. j) Utilize pallets, skids, etc to hasten loading of trailers. k) Use pallets or skids in place of "stationary", four-wheel hand trucks-which should be kept moving. 15 .IDLE-TIME PRINCIPLE :STATEMENTS : Reduce idle or unproductive time both handling equipment and manpower. DESCRIPTION: Idle time is undesirable in nearly any industrial or commercial activities and especially so in the use of Material Handling equipment or manpower. Equipment- and manpower are "Making Money" when fully utilized. Therefore, every effort should be made to plan methods and scheduled equipment to permit full use of both resources.

DOMHS

34 This Principle is very closely re1afed to the Motion Principle and many suggestions made there are equally applicable here. SUBOESTION FOR CARRYING OUT THE IDLE-TIME PRINCIPLE: A. Manpower a) Deliver materials at the proper rate. b) Use indirect labour for material handling. c) Install handling equipment to permit direct labour operators to spend full time on production. d) Combine jobs i.e. one man, 2 machine or jobs--load one while other is eye cycling. e) Be sure that operator is supplied with material-not waiting. B. Equipment a) Scheduled use of Handling Equipment. b) Use radio for dispatching . c) Transfer Equipment to other areas where it can be utilised more fully . 16.MAINTAINCE PRINCIPLE :STATEMENT : Plan for preventive maintenance and scheduled repair of all handling equipment. DESCRIPTION: The suggestion for application of several of the previous principles have implied the importance of preventive maintain and scheduled repairs to the effectiveness of Material Handling activities. Probably very few phases of the Material Handling program can contribute more to overall plant efficiency then well-organized maintenance and repair function. SUGGESTION FOR CARRYJNB OUT THE MAINTENANCE PRINCIPLE: a) Anticipate repairs in order to avoid breakdowns that will take equipment out of service unexpectedly. b) Require operators to make daily inspections of equipment and report findings. c) Plan for detailed, major inspection and reporting on equipment condition at regular intervals. d) Set up a regular lubrication schedule covering all Handling Equipment, using chart to assure adequate lubrication. e) Establish a preventive maintenance program. DOMHS

35 f) Provide adequate maintenance and repair facilities and personnel to handle normal requirement. g) Work out a schedule and work load for repair work to its being done when equipment can be spared and at convenient times. h) Maintain an adequate supply of repair parts and maintenance supplies . i) Keep number of makes and models to minimum to reduce inventory of parts & simply maintenance. j) Paint all equipment on a scheduled basis to keep up appearance and promote care of equipment. k) Require Driver training for all mobile equipment operators. l) Provide adequate instruction in proper operation of all non- mobile equipment . m) Fix responsibility and delegate authority for the maintenance and repair function . n) Send maintenance mechanics' to factory training programs. o) Check with manufacturers on required periodic maintenance, instructions etc. p) Alter maintenance schedules when production schedules change. q) Avoid "over - maintenance". r) Keep floor clear. 17.OBSOLESCENCE PRINCIPLE :STATEMENT: Replace obsolete handling methods and equipment when more efficient methods or equipment will improve operations. DESCRIPTION: As with any other type of physical equipment, Material Handling devices are subject to obsolescence, as well as depreciation. And, in a similar sense, so are handling methods. New

ideas, techniques, methods and equipment are reported every day, and the Material.

Handling engineer must be continuously alert to be sure he is aware of the latest developments. SUGGESTIONS FOR CARRYING OUT THE OBSOLESCENCE PRINCIPLE: a ) Establish a definate replacement policy. b) Set a replacement program and budget. c) Be aware of old equipment that still works. d) Carefully study all alternatives. e) Rent or lease new equipment for a try out period. f) Established a planned, periodic equipment evaluation program. DOMHS

36 g) Keep up with what is new i) Periodicals, Journals, etc. ii ) Books, Handbooks. iii) Equipment shows, expositions iv) Technical society meetings, v) Conferences, short courses . vi) Plant visits viii )Manufacturers Representative. 18 .CONTROL PRINCIPLE :STATEMENT : Use material handling equipment to improve production control, inventory control and order handling. DESCRIPTION: Since Material Handling equipment is used to move materials through the plant and the production process, its use can have a great effect on the control of the items being moved. In many cases, Handling Equipment provides a direct Mechanical path for the movement, and thereby facilitates the control of the material. SUGGESTIONS FOR CARRYING OUT THE CONTROL PRINCIPLE : a. Provide Mechanical Path for materials movement. b) Move materials in lots, batches, containers of a predetermined quantity and size. c) Store, or pack, materials in containers holding a specific number of pieces. d) Use containers (wire mesh) through which contents can be identified and /or counted. e) Utilize 2-way radio or TV to expedite movement and control of materials . f) Make optimum use of Mechanical Handling in order picking, automation, loading. g) Pace production with Mechanical Handling Equipment. h) Build production, inventory, and accounting control features in to the Material Handling Systems. i) Move material on a schedule and in lots to match production, to avoid rush delivery, partial loads, duplicate moves. j) Coordinate handling program (schedule) with purchasing, Manufacturing 19. CAPACITY PRINCIPLE :DOMHS

37 STATEMENT: Use

Handling

Equipment

to

help

achieve

full

production capacity.

DESCRIPTION: In many ways, this principle is a summation of all the preceding ones, in that major objective of material handling is to increase production capacity. Nearly every one of the foregoing principle will contribute in some way to higher production levels. However, the emphasis here is on those facets, of operation and the other principles that are directed specially towards increasing or- making full use of production capacity. SUGGESTIONS FOR CARRYING OUT THE CAPACITY PRINCIPLE: a) Use Mechanical Handling Equipment to assure a uniform, paced rate of flow. b) Operate Equipment

at optimum rate.

c) Plan to utilize return runs of Handling Equipment. d) Fully Load or use container, vehicle, conveyors. e) Make full use of Building cube and floor load capacity to obtain additional square foot. f) Reduce time between operations and departments with Mechanical equipment. g) Efficiently utilise carrier capacity by judicious combination of load, weight, and volume. h) Change size, shape of unit loads to utilise space, equipment capacity, manpower . i) Use area over Aisles (balconies) for additional storage space

make use of rented storage

facilities during peak season to free own space for production. k) Use outdoor storage space for materials not requiring protection from weather- or easily protected. l) Pool Handling Equipment for better utilization. m) Establish one- way aisle to easy traffic congestion. n) Widen aisles to speed Materials Movement. o) Utilize automatic door openers, dock levelers, couplings, etc. p) Eliminate storage areas by using overhead space, moving storage processing during movement etc. q) Use additional safety devices -bo permit, greater speed of movement. 20 . PERFORMANCE PRINCIPLE :STATEMENT: Determine efficiency of handling performance in terms of expense per unit handled. DOMHS

38 DESCRIPTION: As pointed out above, there are many objectives of Material Handling. However , an effective Handling Method may achieve one or several of these objective. The primary criterion for measuring the efficiency of a handling technique is Dollars. Although efficiency can be measured in terms of total cost or equipment performance, the most effective means of measuring efficiency is in terms of dollars per unit handled . It should be pointed out that there are cases where maximum economy is not the overall goal. Some Material Handling devices may be installed to provide higher production rats, safer working conditions, or reduced physical effort. Time or effort saved may be the primary criteria and the cost of handling may be of little or no interest. SUGGESTIONS FOR CARRYING OUT THE PERFORMANCE PRINCIPLE: a) Carefully study all characteristics of the material to identify all possible units which could be used as a basis for comparison. b) Select a common, convenient, standard unit, c) Use the same unit for as many control purposes as possible, d) Avoid changing the unit from department to department, time to time, etc. THE UNIT LOAD CONCEPT: A study of precedent would show that the size weight and bulk of the individual packages used in commerce today are the result of their being handled conveniently by one man. Of course, marketing demands reflect their influence on packages sizes. But, when we come down to the selections of methods, techniques, systems or equipment for Material Handling, our choice is always guided by whether we want to handle one piece on one trip or one piece in a continues flow from one point to another, or several at a time either in a continues flow or intermittently. The Unit Load Principle implies that materials should be handled in the most efficient , maximum size unit, using

mechanical means to reduce the number of moves

needed for a given amount of material. A Unit Load has been defined by Professor James R. Bright as: A number of items or bulk material, so arranged or restrained that the mass can be picked up and moved as a single object too large for manual handling, and which upon being DOMHS

39 released will retained its initial arrangement for subsequent movement. It is implied that single initial arrangement for subsequent movement. It is implied that single objects too large for manual handling are also regarded as Unit Loads In summarizing the Unit Load concept, Johnson has stated that it should: 1. Perform a minimum number of handlings and eliminate Manual handling. 2. Assemble materials into a Unit Load for economy of Handling and storage. 3. Assemble materials into Unit Load as soon as possible and keep n that form as soon as possible. 4. When necessary, redesign packages and cartoons for better assembly into unit loads and retain the unit load form to use all possible cube and prevent product damage. 5.Make the Unit Load as large as possible considering the imitations of building, Handling Equipment, Production areas, volume of material required, and common carrier dimensions and capacities . ADVANTAGES OF UNIT LOAD : 1) Permits handling of larger loads. 2) Reduces Handling costs. 3) Faster movements of goods. 4) Reduces time for Loading and Unloading. 5) Reduces packaging costs. 6) Maximum use of cubic space. 7) Reduces Pilferage in transit and storage. 8 ) Less time wasted in tracing stray items,, 9 ) Reduces Product damage. 10) Reduces Physical Inventory Time and cost. 11) Better co-ordination of deliveries to Production. 12) Safer Handling, 13) Better Customer service. 14) Reduce s Transportation Cost. 15) Lower Insurance Rate for good in Transit. 16) Reduces time and expenses of labeling Individual items. 17) Utilization permits uniform stock placement, resulting in uncluttered aisles. DOMHS

40 18) Production Operators need not waste valuable time in helping to move materials. 17) Items themselves need not be uniform as unitizing medium provides uniformity. 18) Irregular items can become stable load. 19) Provide basis for overall handling system within physical distribution cycle . 20) Provide basis for handling systems within plant. 21) Unitized load stabilize stacks of materials. 22) Unitizing Medium can provide uniform temperature and moisture control of goods. 23) Unitizing Medium can protect loads from foreign elements. 24) Maximum accessibility of stored goods 25) Reduces Handling of individual items. DISADVANTAGES OF UNIT LOADS : In spite of the overwhelming evidence in favour of applying the unit load concept, there are, nevertheless, some disadvantages, such as: 1. Cost of Unitizing, 2. Cost of De-unitizing, 3. Equipment required . 4. Space required. 5. Lack of flexibility. 6. Wasted cube within Unit Load. 7. Tare Weight of Unitizing Medium. 8. Problem of returning empty containers 9. Possible damage due to mishandling of large Unit. 10.Common carriers are not uniform in size. 11.Transfer Equipment often not available on both "ends" of the move. EQUIPMENT CONCEPTS :In the Material Handling equation it was suggested that an analysis of the materials to be handled and the moves to be made should indicate the method, However, before becoming involved in problem- solving details, it is felt that a brief introduction to Material Handling Equipment will prove helpful in comprehending the overall objective of the Handling analysis-to design a method. And the method nearly includes some type of Handling DOMHS

41 Equipment. Therefore, one of the major task of Material Handling Engineer is to become acquainted with the large and overgrowing field of handling equipment, although it would be next to impossible for an individual to become intimately acquainted with all the types. THE PLACE OF EQUIPMENT IN THE HANDLING SYSTEM :As implied several times previously, equipment is not always required in order to solve a Handling problem. Usually the simplest and most economical method should be utilized, which may not require any equipment In fact, the work simplification approach suggests the following

general

procedure :

1. Eliminate the move . 2 . Combine the move with some other function processing , inspection, storage,

etc.

3. Change the sequence of activities to shorten, eliminate, and after the move requirement. 4.Simplify the move to reduce the scope, extent, distance, method, equipment, etc. Then-after having accomplished the above -the equipment would selected if necessary. THE ROLE OF MANUAL HANDLING :A factor frequently overlook in the rush to mechanize or automate is that Manual Handling, may be the easiest, most efficient, and least expensive method of moving materials. So, even before attempting to select a piece of Handling Equipment the analyst should very carefully explore the possibility of Manual Handling Methods. Some of the characteristics which would generally tend in four Manual Handling are : 1 .Material Type a. Unit 2 . Material Characteristics a. Small

b. Light

c. Fragile

f. Solid or containerized

d. Costly

e . Safe to handle

g . Scrap

3. Material Quantity a. Small , low volume. b. Single items one at a time. 4. Move Source and Destination-close together. 5 .Move Logistics

.

a . Work place( small area ). DOMHS

42 b . Multi-plane. c. Level to level. d . Variable profile. e. Complex path. f. Working height. g . Complicated move . 6 . Move Characteristics a. Short distances b. Infrequent c. Low rate d .Non-uniform rate e . Variable speed f. Irregular g. Intermittent h . Variable i. Low percentage of Handling j .Variable sequence. 7. Move Type a. Maneuvering b. Positioning 8. Handling Unit-same as items 1 & 2 9. Equipment a. Probab1y none b. Operator controlled 10. Manpower a. Relatively small amount of operator time required b. Low hourly rate. 11. Physical Restrictions (As implicit by other characteristics of the problem, above : otherwise , not applicable.)

DOMHS

43 It should be pointed out that all the above characteristics do not imply only manual methods. Some of them, usually in combination with other characteristics or because of the nature of the nature of the material, will require Mechanical devices. Only after it has been proved that Manual Handling is more costly, too dangerous., too slow, etc .should the analyst turn his attention to Mechanical Equipment. NON-POWERED EQUIPMENT: Included with the several hundred types of Material Handling Equipment are a

number of non powered

or

manually

operated

or controlled, i.e., not "mechanized".

The following list indicates the situations in which non-powered or manual equipment may fit into handling system. 1 .Where handling volume is limited, or handling activity can be extended period

of

over

a

long

time.

2. Where building limitations preclude use of heavier or bigger devices. 3. Where service conditions, such as confined areas, explosive atmosphere, or quiet surroundings necessitate the advantage of non- powered equipment. 4. Where equipment is used not only for handling but for storage or display . 5. When investment capital is limited. 6. When the required Flexibility, utility, mobility, arid portability can only be obtained in a non-powered floor device . 7. Where the maintenance facility are minimal or non-existence 8. Where the mobile equipment must be tailored to the production need. 9. Where the operating efficiency of non-powered equipment higher than that of other type. 10.When loads are relatively light and equipment .is to be manually moved. 11. For stand-by use. 12. For durable, low cost operation. The above possibility should be checked before Mechanized or Powered Equipment is seriously considered. SELECTION OF MATERIAL HANDLING EQUIPMENT :A wide variety of Material Handling Equipment is in the market ; some equipment's are for general, purpose use. The choice of a particular equipment depends upon the DOMHS

44 specific requirement or the condition an industry. Naturally,

the best equipment will be

the one which permits smooth and continuous production flow, involves less accidents, reduces production cycle time, promotes better working condition, incurs less fatigue to the operators and brings down the Material Handling Costs . The following factors may be considered while selecting a Material Handling Equipment ; MATERIAL TO BE HANDLED: The size of the material, it's shape, weight, delicacy, nature (solid, liquid, gases,) and its chances of getting damaged during handling, etc, should be considered. 2) PLANT BUILDINGS AND LAYOUT :Widths of aisles, inequality in floor levels, width of doors, height of ceiling, strength of floor and walls, columns and pillars, etc., to a great extent influence the choice of Material Handling Equipment. For example, low ceiling heights may not permit stacking of palletized materials, weak roofs limit the use of overhead conveyor and steps between two floorswill not allow trucks to operate. 3) TYPE OF PRODUCTION MACHINE: Different Machines have different outputs per unit time. The Material Handling Equipment should be able to handle the maximum output. 4) TYPE OF MATERIAL FLOW PATTERN: A

vertical .flow

pattern

will

require

elevators,

conveyors pipes, etc.,

whereas' horizontal flow pattern will need trucks, overhead bridge cranes, conveyors, etc. 5) .TYPE OF PRODUCTION: The type of production affects to a large extent the selection of Material Handling Equipments. conveyors are more suitable for mass production in on fixed routine and powered trucks for batch production; because conveyors though costly, can handle more

volume of production per unit time as compared to trucks, whereas a truck is more

flexible equipment. 6) Cost of Material Handling Equipment/ 7 ) Handling Cost. 8 ) Life of Equipments DOMHS

45 9) Amount of care and maintenance required for the Material Handing equipment. 10 ) Safety of equipment. 11 ) Equipment Reliability. EQUIPMENT SELECTION PROCEDURE :The Procedural Steps involved in Equipment Selection have been listed below l. Relate all factors pertinent to problem viz ; the material , the move and the method. 2. Determine appropriate degree of Mechanization. 3. Make a tentative selection of Equipment types. 4. Narrow the choice. 5. Eva1ate the alternative. 6. Check the selection for with the rest of the system. 7. Select the specific type of Equipment 8 . Proper specifications. PROPERTIES OF SELECTED MATERIAL HANDLING EQUIPMENT The Equipment selected should, l. Fit into the Hand1ing System, 2. Combine Handling with other function. 3. Optimize Material Flow. 4. Be as simple as it is practicable. 5. Utilize Gravity wherever possible. 6. Require s minimum of space. 7. Handle as large a load as is practical. 8. Make the move safely, in terms of both manpower and material. 9. Use Mechanization judiciously. 10.Be flexible, adaptable. 11.Have a low dead-weight to pay-load ratio, 12.Utilise a minimum of Operator time. 13. Require a minimum of loading, unloading, and re-handling. 14. Call for as little Maintenance, repair, power and fuel as possible. 15. Have a Long, useful life. DOMHS

46 16. Be capable of Capacity Utilization. 17. Perform the Handling operations efficiently and economically. TYPES OF MATERIAL HANDLING EQUIPMENT: Generally there are following types of Material Handling Equipment: 1) CONVEYOR These are gravity or powered devices, commonly used for moving uniform loads continuously from point-to-point over fixed paths, where the primary function is conveying. They prove economical if the flow of material is continuous. Classification: A. Belt Conveyor a. Flat b. Trough c. Portable B. Bucket a. Gravity Discharge b. Pivoted Bucket (Bucket Elevator) C. Chain or Cable a. Apron b. Arm c. Car Type d. Drag e. Flat-top f. Flight i. Power and Free j. Slat k. Tow i) Overhead ii) Flush iii) Under-floor DOMHS

47 l. Trolley D. Chute E - Pneumatic conveyor a. Pipeline b. Air activated gravity c. Tube F. Roller Conveyor a. Gravity b. Line c. Portable d. Rack G. Screw Conveyor a. Screw attachment i) Ribbon Conveyor ii) Paddle Conveyor b. Movement of Material i) Horizontal Screw Conveyor ii) Vertical Screw Conveyor H. Vibrating I. Wheel Uses: Conveyors are generally useful when: a. Loads are Uniform b. Material moves continuously c. Route does not vary d. Load is constant e. Movement rate is relatively fixed f. Conveyors can By-pass Cross traffic g. Path to be followed is fixed h. Movement is from one point to another DOMHS

48 i. Automatic counting, sorting, weighing Dispatching is needed j. In-process storage or inspection is required. k. Necessary to Pace Production. l. Process Control is needed. m. Controlled flow is required n. Handling hazardous material o. Handling Material at extreme temperature or under adverse condition. p. Handling is required on dangerous areas. q. Manual Handling and or lifting is undesirable. r. Integrating Machine into a "System" s. Handling between workplaces t. Flexibility is required to meet changes in production processes volume or space. u. Conveyor can be installed overhead to save floor space. v. Necessary to make constant visual check of production processes. 2. CRANES AND HOISTS : These overhead devices are usually utilized to move varying loads, intermittently, between points within an area fixed by the supporting and guiding rails, where the primary function is Transferring. Classification : A. Cranes a. Jib i) Floor Mount ii) Top and bottom iii) Wall Mount b. Traveling i) Bridge I) Top Running II) Under Running ii) Gantry c. Stacker i) Crane DOMHS

49 ii) Storage Machine d. Mobile B. Elevators a. Bucket i) Continuous I) External Discharge II) Internal Discharge ii) Spaced I) Centrifugal Discharge II) Positive Discharge b. Portable C. Hoists a. Chain Type b. Pneumatic c. Electrical D. Monorails Uses : Cranes and Hoist are most commonly used when, a. Movement is within fixed area. b. Moves are intermittent. c. Load vary in size or weight. d. Cross Traffic would interference with conveyors. e. Unit handled are not uniform. 3. INDUSTRIAL TRUCKS : These are hand or powered vehicles (non-highway) used for the movement of mixed or uniform loads, over various paths having suitable running surfaces and clearances, where the primary function is Maneuvering or Transporting. Classification : A. Non-powered a. dolly b. 4-wheel hand truck DOMHS

50 c. Hand Lift (jack) d. semi-live skid e. stacker f. trailer B. Powered a. Driver Walk i) Platform Type ii) Pallet Type iii) High Lift Fork b. Driver Ride i) Platform I) Low Lift II) High Lift ii) Pallet Lift iii) Telescopic fork lift Uses : Industrial Trucks are generally used when, a. Material is moved intermittently. b. Movement is over varying routes. c. Loads are uniform or mixed in sizes and weight. d. Length of move is moderate. e. Cross Traffic will prohibit Conveyors f. Clearances and running surfaces are adequate and suitable. g. Most of the operation consist of Handling. h. Material can be put up into Unit Load. SCREW OR SPIRAL CONVEYOR :INTRODUCTION : A conveyor consisting of a continuous or broken blade helix screw fastened to the shaft and rotating in a trough so that the revolving screw advances the material. Depending upon the type of screw attachment. DOMHS

51 Screw Conveyor are of Two types as follows, RIBBON CONVEYOR : It has the screw attached to the shaft with arms or spokes so as to leave space between the screw and shaft. PADDLE CONVEYOR : It has the screw interrupted and shaped as Individual paddles. CONSTRUCTION :HORIZONTAL SCREW CONVEYOR : Screw Conveyor are installations serving to move materials over a trough by a rotating screw. This is formed by a Helical Blade attached to a drive shaft B which is coupled to a drive 1 and supported by end bearings 2, 6 and by inner bearing 4. The trough 7 of the round bottom shape is topped by inner bearings 4. The Trough 7 of the round-bottom shape is topped by a cover plate 3 with an opening 5 for loading the conveyor. A similar unloading opening 9 is provided in the bottom of the trough. The Loading and Unloading point can be located anywhere on the trough. (fig 3)

FIG 3. HORIZONTAL SCREW CONVEYOR VERTICAL SCREW CONVEYOR : Screw conveyors easily negotiate rising gradient and can also operate vertically, lifting material upto 15m at a rate of 50t/h. In this latter case the vertical Conveyor is assisted by

DOMHS

52 screw feeder or a Horizontal Screw Conveyor which serve to create thrust at the foot of the lifting screw as shown in figure 4, In general there are three types, 1. HELICOID SPIRALS : Use for Dry Materials ranging in size from powder to medium lumps. 2. RIBBON SPIRALS : Adopted to handle coarsely-broken and sticky loads. 3. PADDLE SPIRAL AND CUT FLIGHTS : Utilize to convey flow-resistant solids tending to cake.

This type is also employed in installations combining transportation with processing

(mixing, crushing, wetting, etc.).

FIGURE 4. VERTICAL SCREW CONVEYOR WITH A SCREW FEEDER TYPICAL SCREW CONFIGURATION (FIGURE 5) :-

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53

FIGURE 5. TYPICAL SCREW CONFIGURATION (a) HELICOID SPIRAL : (b) RIBBON SPIRAL (c) CUT FLIGHTS CHARACTERISTICS : 1. Feeding can be from top, end, or bottom. 2. Discharge is from end or bottom. 3. Screw is driven from one end. 4. Screw can be right or left hand. 5. Can be both, to deliver at both ends from the middle, or to bring two material together at the middle. 6. Screw is designed to accommodate specific materials and/or functions. 7. Usually runs on horizontal or incline, but at a reduced capacity. 8. Can be used vertically as an Elevator 9. Relatively low cost. 10. Compact and can operate in close quarters. USES : Screw Conveyors, by virtue of their design ensuring gas tightness, are widely used 1. to handle dusty or hot loads (almost any temperature) and those which liberate harmful gases. 2. to move fibrous material. 3. to move pulverized or granular material but may need special screw for some. 4. to control Material flow. 5. as a mixer or blender.

DOMHS

54 LIMITATIONS : 1. Screw Conveyors invite difficulties when the load is abrasive, coarsely broken, or sticky. 2. Commonly made in 10-12 feet section. 3. Certain amount of degradation of material. 4. Length limited by torque capacity of shaft and drive. 5. Operate at 10-120 feet per minute. 6. Handle upto 10,000 cu. ft per hour. 7. Not recommended for handling materials which are degraded due to breakage. APPLICATION : 1. Oil Refineries.

2. Chemical Industries.

3. Sugar Mills.

4. Soap Industries etc.

DETERMINATION OF SALIENT DIMENSION AND POWER REQUIREMENT :The Helical Blade forcing the load along the trough when the shaft is set rotating is made of 4 to 8 mm steel plate and attached to the shaft by welding. The Trough is commonly fabricated from steel sheet between 2 to 8 mm thick. The Screw pitch t = (0.5 to 1.0) D, where D is the screw diameter. Light weight are handled by screws with a wide pitch. The screw diameter is governed by the lump size and at least four times that the maximum lump size in case of unsize bulk materials. The screw speed is governed by the nature of the load and screw diameter, increasing inversely with the bulk weight, screw diameter and the intensity of abrassive action of the material. Conveyors handling heavy materials commonly operate at 50 rpm and those designed to convey light loads, at up to 150 rpm. The Cross-sectional loading of a Screw Conveyor is given by, Π D2 S =ϕ 4 where ϕ is the capacity factor which, to take account of the accumulation of load at inner bearings, is always by far smaller than unity. The recommended values of ϕ are as follows : Heavy-weight abrasive load

-------- 0.125

Heavy-weight mildly abrasive

-------- 0.25

Light -weight mildly abrasive

-------- 0.32

Light-weight non abrasive

-------- 0.4 DOMHS

55 In designing short screw conveyors which have no inner bearings, the above values can be increased by factor of 1.5 to 2. On the other hand, they must be reduced by 10 to 15 percent when the Conveyor is intended to handle free-flowing materials. The hourly capacity of a Helicoid Spiral Conveyor by tonnage can be estimated by the formula. Q = 3600 S v γk where k is a factor introduced in designing inclined conveyors, for their capacity is always less than that of horizontal ones. Approximate values on the angle of rise are given below : β, deg . . . 0

5

10

15

20

k.......1

0.9

0.8

0.7

0.65

Since the speed of conveying is ν=

tn 60

We arrive at the Capacity Formula , Q = 3600 ϕ

Π D2 tn γ k 4 60

= 4 > ϕ γ t n D2 k In capacity calculation, the speed is adopted from practical experience at n = 60 / √ D , for light non-abrasive loads n = 45 / √ D , for heavy non abrasive materials n = 30 / √ D , for heavy abrasive stock where D is the screw diameter in m. The Power requirement in kw referred to the drive shaft can be determined for Horizontal Conveyors from Nh = Co

Q L 367

and for sloping installation from, Ns

=

QH 367

+

Co

QL 367

In the above formulas, the friction factor, Co, is adopted from the following tabulation based on experimental data : DOMHS

56 Flour , cereals, sawdust . . . . . . . . . . . . 1.2 Peat, Soda

ash,

pulverized

coal,

finely ground

Chalk . …………... . . . . . . . . . . .. . . . . 1.6 Coal ( lump anthracite and bituminous, air-dry brown ) , rock salt . . . . . . . . . ………………….…….. 2.5 Gypsum,

dry

Clay,

sand,

cement,

ash,

lime,

moulding

sand . . . . . . . . . . . . . …………… . . . . 4.0 High values of friction factor are attributed to the friction of material on trough walls and screw which is so high that may bring about of the load. The capacity of Ribbon Spiral conveyors is 20 to 30 percent less than that of the Helical Spiral type and the power requirement are also smaller by roughly 10 percent. COMPARISON : Comparative studies involving Screw and Belt Conveyor of the same 30 ton/hour capacity have revealed that the operating costs of the former are on par with those of the latter at a conveying length of 10 m but exceed them twice when the length is 100 m. PROBLEM :A Screw used for conveying salt through distance 6 m, diameter of Screw is 15 cm & t = 10 cm, specific weight of salt is 1.46 ton/m3 , specific friction factor is 2.55, capacity factor is 0.39. Calculate amount of salt conveyed in one hour & power requirement of drive conveyor, Take n=

35 D

Solution : Given, L = 6m

,

Co = 2.55

t = 10 cm

,

ϒ = 1.46 ton/m3

n= v=

35 = D

,

D = 15 cm ,

,

ϕ = 0.39

,

find Q & Nn.

35 = 90. 36 rpm 0.15

t n 0.1× 90.36 = = 0.1506 m / s 60 60

S= ϕ

Π (0 − 15) 2 Π D2 = 0.39 4 4

DOMHS

57 = 0.006892 We know , Q = 3600 Sv ϒk Since

β = 0 deg therefore k = 1 Q = 3600 x 0.006892 x 0.1506 x 1.46 = 5.45 tons/hr Nn = Co = 2.55

Q L 367 5.45 × 6 367

= 0.2272 kw NOTE : If the Power required is in H.P., than the conversion factor is 1 H.P. = 0.736 kw REVIEW QUESTIONS :Q.No.1 : What are the different principles of material handling ? Explain Gravity Principles with application ? Q.No.2 : List various material handling equipment and give their field of application ? Explain the selection criteria for the material handling equipment. Q.No.3 : Explain the principles the unit load ? Q.No.4 : What handling situation and problem characteristics suggest (a) No material handling equipment (b) Manual equipment (c) Mechanized equipment (d) Automated equipment ? Q.No.5 : Classify and explain the various type of material handling equipment ? Q.No.6 : Explain different type of conveyors ? You relative merits & demerits ? Q.No.7 : Explain working principle of screw conveyor ?

Give characteristics and field of

application screw conveyor ? Q.No.8 : What are the different type of screws used in screw conveyor ? Explain with application ? When will you select ribbon type of screw ? Q.No.9 : Give the complete design procedure for a screw conveyor ? Q.No.10 : Calculate the amount of dry powder conveyed in one hour by the screw conveyor, which is used for conveying the material through a distance of 8 metre. Diameter of screw is 15 cm. Specific weight of the powder material is 1.46 ton/m3 , Specific friction factors 2.55, Capacity factor 0.39. Also find the power required to drive the conveyor.

DOMHS

58 Q.No.11 : A screw conveyor is to be used in chemical plant for conveying some powder through a horizontal distance of 12 meter. The diameter of screw is 30 c.m. and reduction ratio is 1:20. Calculate the quantity of powder handled per hour and power required for paint. Pitch of the screw t = 0.78 D, Specific weight r = 1.2 ton/m3 , Specific friction factor Co=2, Capacity factor ϕ = 0.32 ? Q. No.1 : (a) Explain following principles of material handling (i)

principle of gravity.

(ii)

Principle of automation

(iii)

Ideal time principle

(iv)

Capacity principle

(v)

Dead weight principle

(b) What do you understand by technical specification of a material handling equipment ? Q.No.2 : (a) Suggest suitable material handling equipment for following application. Also justify your selection ? (i) Ash disposal in thermal power plant. (ii) Scooter assembly line in an automobile industry. (iii) Cotton seed hand. (iv) Amorphous chemical handling in pharmaceutical industry. (b) What are the principle of material handling. Q.No.3 : (a) Compare the belt conveyor and screw conveyor w. r. to their advantage disadvantage and limitation ? (b) What factor are affecting selection of material handling equipment. Q.No.4 : (a) Explain in detail the unit was concept with advantages and disadvantages. (b) Explain following principle of material. (i)

Planning principle

(ii)

Material flow principle

(iii)

Space utilization principle

(iv)

Standardization principle

Q.No.5 : (a) What are the principle objectives of mechanical handling ? DOMHS

59 (b) Explain screw conveyor with neat sketch & working of it ? Q.No.6 : (a) Explain in detail how salient diamension and power requirement of screw conveyor is determined ? (b) List various material handling equipment and give their field application ? Q.No.7 : (a) What are the various types of screws used in screw conveyor ? When will you select ribbon type screw ? (b) A screw conveyor is to be used in chemical plant for conveying some powder through a horizontal distance of 12 meters. The diameter of screw is 30 cm and reduction ratio1:20. Calculate the quantity of powder handled per hour and power required for plant pitch of screw , t = 0.78 D, specific weight , r = 1.2 ton/m3 , specific function factor Co = 2, capacity factor φ = 0.32 Q.No.8 : (a) Give complete design procedure for screw conveyor ? (b) Calculate the amount of dry powder conveyed in the hour by screw conveyor which is used for conveying the material through a distance of 8 meter. Diameter of screw is 15 cm sp weight of powder material is 1.46 t/m3 , specific friction factor 2.55, capacity factor 0.39. Also find out the powder required to drive the conveyor. Q.No.9 : (a) Explain different types of conveyor. Give their merit and demerit ? (b) Explain selection criteria for material handling equipment ? Q.No.10 : (a) Give different principles of material handling. Explain ‘Gravity principles’ and its application. (b) What do you understand by equipment specification ? Describe the specification of screw conveyor ? Q.No.11: (a) What handling situation and problem characteristic suggest. (b) no material handling equipment. (c) Manual equipment. (d) Mechanized equipment. (e) Automated equipment. Q.No.12 : (a) Design the screw conveyor to find out (i)

conveying capacity.

(ii)

Power required for horizontal and inclind screw conveyor. DOMHS

60 (b) What are various characteristics of screw conveyor ? Q.No.13 : (a) Explain principle of unit load ? What are basic way to move unit load ? (b) A screw conveyor is used for conveying oilseed from store to the expellor which is situated at a length of 10 meter. The diameter of screw is 30 cm. Calculate the amount of material conveyed for the speed of 60 rpm and also the power required. Assume – Capacity factor = 0.4 φ Sp. Function factor = 1.2 Sp. Weight of oil seed = 0.4 tonnes/m3 (c) What is function of snub flillag ? Q.14. (a) Explain ribbon type screw conveyor c.configuration with neat sketch ? MEGA OFFER FOR ENGINEERING STUDENTS

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61

UNIT - III BELT CONVEYOR :- Introduction Types of Drives used for Belt Conveyor. Methods of maintaining belt Tension Optimization of Cross Sectional Area of Belt Conveyor supported on (a) Two Roller System (b) Three Roller System, Determination of Salvant Dimensions and Power Requirement. BELT CONVEYOR :In Belt Conveyor, the belt made up of plain fabric, rubber, plastic, leather, metal, etc., operating over suitable drive, is used as the conveying medium. Belt Conveyors can be operated over a long distances, being easily adapted the natural counter of the ground. The belt Conveyor consist of a driving traction element 2 in the form of an endless belt also giving support to the load, a drive linked up with a drive pulley 1, a take-up with a pulley 6 and a counterweight 7 arranged at the foot end, belt-carrying idler rollers 4, return-run idlers 8, a load in device 6, an unloading arrangement 3, a snub pulley 10, and a belt pleaner it. On some installations, a slider trough in metal or timber is used as the roadbed over which the belt travels instead of idlers. All conveyor components are supported by a metal frame 9. (Figure 6)

FIG 6. SCHEMATIC DIAGRAM OF A STATIONARY BELT CONVEYOR

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62 ADVANTAGES : 1. High handling capacities. 2. Simple construction. 3. Light weight. 4. Operational reliability and convenience. 5. Comparatively Low power consumption. 6. Belt Conveyor appear, as the practice proves, to be more economical than railways and automotive transport over distances of 25 km and even 100 Km when the tonnage to be hauled amounts to 25 million tons per year. APPLICATION : Belt Conveyors enjoy wide-spread application in various fields for moving diverse loads and bulk materials. They cope with hauling loads from one location to another within the process in inline production, deliver foundry sand, are employed in mining operations, at coalhandling plants, granaries, etc. LIMINATION : 1. Conveyor belting is, however, a costly material with a comparative short life. To spare it, limitations are imposed on the use of belt conveyors at elevated and sub-zero temperature. 2. The loss of light weight bulk material carried away as dust or spilled from the belt along its path is another objectionable feature.

FLAT BELT CONVEYOR :INTRODUCTION : In Flat Belt Conveyor, flat belt supported on slider bed or idlers (roller), is used for handling materials, packages, or object placed directly upon the belt. CHARACTERISTICS : 1. Belt supported on flat surface is used as carrier of objects or as basis for assembly line. 2. Belt supported by flat rollers will carry bags, boxes, cartoon. 3. Top and return runs of the belt must be utilized. 4. Will operate on level, incline up to 28 degrees, or downgrade. 5. High capacity. 6. Capacity easily adjusted. DOMHS

63 7. Relatively easy maintenance. 8. Versatile. 9. Provide continuous flow. USES : 1. Carrying objects - units, cartons, bags, some bulk material. 2. Assembly lines. 3. Moving people. LIMITATIONS : 1. Fixed Path. 2. Relatively high cost. 3. Elevating angle limited. 4. Straight line flow between pulleys. 5. Problems with horizontal turns. 6. Can convey solid parts TROUGHED BELT CONVEYOR :A Belt Conveyor with the edges elevated on the carrying run to form a trough by conforming to the shape of troughed carrying idlers or other supporting surfaces. Provides a greater capacity than the Flat Belt Conveyor for bulk material-upto 2000 tons per hour. Used primarily for bulk materials and those which would slide or fall off the belts. PORTABLE BELT CONVEYOR :It is nothing but the portable arrangement of Flat Belt Conveyor. Used for loading and unloading trucks, between machines, scrap handling, etc. TYPICAL BELT CONVEYOR PATH :Conveyor transportation systems exist in various layouts depending on the purpose served. A few-typical arrangement are depicted in Figure 7.

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64

FIG 7. TYPICAL BELT CONVEYOR PATH (a) HORIZONTAL ; (b) INCLINED; (c) WITH CONCAVE AND CONVEX TRANSITION CURVE; (d) COMBINATION OF A HORIZONTAL CONVEYOR WITH AN INCLINED ONE; (e) HORIZONTAL CONVEYOR WITH A MOVABLE TRIPPER.

TYPES OF DRIVES USED FOR BELT CONVEYOR :The driving Traction required for moving the belt and the load, is provided by friction between the belt and driver pulley. A Drive consists of a motor 1, a spur or worm gear reduction unit 3, a drive pulley 5 and couplings 2, 4 linking the motor to the reducer and this to the pulley.(FIG 8) Inclined Belt Conveyor are fitted with holdback devices and brakes preventing possible backward movement of the Conveyor should the drive motor stops A belt holdback is sometimes used instead of a brake. Horizontal belt conveyors, too requires brakes. These serve to minimize coating after the motor has been stopped, to prevent the pilling up of load at the next conveyor or the plant served, and to prevent accident in the event of emergency stoppage. The drive should be capable of moving the belt at a constant or variable speed changed steplessly or in steps depending on process requirements.

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65

FIG 8. TYPICAL ARRANGEMENT OF BELT CONVEYOR DRIVE According to Eulers, the tension, Ttight, in the entering or tight side of the belt and that, Tslack, in the leaving or slack one are correlated,

T tight = T slack x efa where, a is the angle of wrap of the belt, rad ; f is the coefficient of friction of the belt on the pulleys

ef α is the traction factor characterizing the tractive performance of the drive pulley. The above relationship assumes that no belt slip exists For given values of T tight and Tslack, the maximum effective pull which can be transmitted by the drive is given by

(e f α − 1) Pmax = Tslack (e - 1) = Ttight e fα fα

The requirement enabling the drive to function is that the actual pull should be less than the maximum value, i.e., P < P max The coefficient of friction f is a function of the belt type, the material of pulley face, and ambient conditions. For the fabric ply-constructed belting it is as follows : DOMHS

66 Pulley Cast-iron : dry

. . . . . . . . . . . . . . . . . 0.3

moist

. . . . . . . . . . . . . . . . . 0.2

wet

. . . . . . . . . . . . . . . . . 0.1

Wooden : dry

. . . . . . . . . . . . . . . . . 0.35

wet

. . . . . . . . . . . . . . . . . 0.15

Rubber-lagged : dry

. . . . . . . . . . . . . . . . . . 0.4

moist

. . . . . . . . . . . . . . . . . . 0.15 Fabric ply constructed belting with PVC covers display a reduced coefficient of

friction, amounting to 0.2 for plain pulleys and to 0.28 for lagged ones. Wire belts call for adopting the following values of the coefficient of friction : On Steel Pulley : in humid surroundings .. . . . . . . . . 0.15 in dry room

. . . . . . . . . 0.20

On rubber lagging in dry room

. . . . . . . . . 0.35

On wooden lagging in dry room

. . . . . . . . . . 0.30

For a steel band conveyor with plain pulleys, f = 0.10; for rubber or wood-lagged pulleys, f = 0.27. The driving traction can be boosted by increasing either the coefficient of friction or the angle of wrap of the belt. There are basically two types of drives used for belt Conveyor, 1. SINGLE DRIVE WITH SNUB PULLEY : In most of the conveyors, α > 180 deg by virtue of snub pulleys.(fig 9a) 2. TANDEM DRIVE : Long-center Conveyors for handling heavy loads are frequently equipped with a dual or tandem drive in which the belt is snubbed in excess of 2 Π (390 to 430 deg) to provide for high driving traction. Tandem drives, apart from being complicate, are a source of high belt wear

DOMHS

67 and fatigue as well as ply separation resulting from reverse bends. These factors should be given due consideration in point of economy before adopting a tandem drive for use. A non-uniform circumferential speed of drive pulleys resulting from non-uniform belt wear brings about belt slip. This is another limitation inherent in the tandem drive with a rigid pulley link-up. On high-power installations this may be overcome for dependable performance by using an equalizing tandem drive with a planetary gear or fluid motors which serve to distribute the motor torque between the pulleys in a certain proportion depending on the estimated traction.(fig 9b)

FIG 9. BELT CONVEYOR DRIVES (a) SINGLE DRIVE WITH SNUB PULLEY, (b) TANDEM DRIVE. METHOD OF MAINTAINING BELT TENSIONS (BELT TAKE-UP) :Besides taking up belt stretch and eliminating belt sag, this serve to maintain traction between the belt and drive pulley, preventing belt slip.

Tension is maintained by

displacing a take-up pulley. In use are take-up providing for an uncontrolled tension and those controlling the tension depending on the torque applied to the drive pulley. Coming under the first-named group DOMHS

68 are mechanically operated devices (screw, rack-and-pinion, gravity types) maintaining a constant tension. Serving the same purpose automatically, though by means of extra controls, are compact pneumatic and Hydraulic cylinders gaining now popularity. The take-up is located in a place where belt tension is a minimum, necessitating a minimum is chief consideration in sitting the Take-up. There are two types of take-up as follows, 1. SCREW TAKE-UP : Referring to Figure 10a, the take up pulley shaft is supported by bearings contained in housings 1 capable of displacing along guide 2. When the bearing are accommodated in the pulleys hubs, the shaft is fitted to the housing directly. In a Screw-type take-up, the housings are connected to screw 3, operating as compression members when the belt is arranged as indicated by solid lines or as tension ones with the belt operating as shown in dash lines. Long compression screws should be proportional to resist the load bending or replaced by screws subject to tension. The take-up travel, adopted on the center distance and path of the conveyor, must offset the belt elongation due to load, temperature, and wear. It must also provide for unobstructed maintenance and repair. Standard take-up travel of Horizontal Conveyors is commonly 1/100th of the belt length or 400 mm, whichever is greater, and that of inclined installations is 3/200th of the length. A belt stretch exceeding the above values is taken care of by replacing the belt. Screw-type take-ups require careful attention and adjustment to offset belt stretch. On the other hand, it may produce an excessive tension in the belt, overloading it. Taking into account these limitations, their use is confirmed to short-center conveyors operating under the conditions of practically stable ambient temperature. At the same time, Screw-type take-ups are attractive owing to their compactness. A preferable arrangement is when the screws are not geared to each other. This enables a nonuniform belt stretch set up across the width to be taken care of individually so as to prevent the belt from running off the pulley. The possibility of non-uniform belt stretch set up across the width to be taken care of individually so as to prevent the belt from running of the pulley. The possibility of non-uniform loading of the screws is allowed for by introducing a load factor of 1.5 to 1.8 into the strength calculations. On some installations, the screw-type take-up is provided with means of balancing the screw loads.

DOMHS

69 2. GRAVITY TAKE-UP : A more advanced kind providing for an automatic belt stretch control and constant belt tension is the Gravity-Type Take-up illustrated in Figure 10b. By analogy with the screwtype, the take-up pulley travels along guides being attached to housings. Alternately, it can be displaced by means of a trolley acted upon by a weight, G, attached to a rope or chain, which produces constant belt tension T1 and T2. The weight can be applied directly as shown in Figure 10c in which case the take-up dispenses with the rest of the parts save the take-up pulley. Excessive trolley travel and weight displacement are checked by limit switches. Gravity take-ups are rather bulky and therefore find application on stationary conveyors only. The force applied by the take-up should equal the geometrical sum of the tensions in the belt runs at the drive pulley during starting the conveyor plus the effort required to displace the take-up pulley along the guides or trolley along the rails. A tension factor of 1.2 to 1.5 is introduced in calculating the force.

FIG 10. TYPICAL TAKE-UPS a) SCREW TYPE : (b) GRAVITY TAKE-UP ARRANGED AT TAIL PULLEY : (c) GRAVITY TAKE-UP ARRANGED AT DRIVE PULLEY DOMHS

70 DETERMINATION OF SALIENT DIMENSIONS OR DESIGN OF BELT CONVEYOR :1) FLAT BELT CONVEYOR : (FIG 11 a) Referring to the fig, when the belt is flat, it is assumed that the cross-sectional area of the material on the belt to be roughly a triangle and varies with the belt width (B). Let, B = Belt width. b = base (width) of material on belt = 0.9B - 0.05m h = height of material on belt ϕ = angle of repose F1 = cross sectional area of the material on belt. (as shown in figure ) = bh/2 From fig, tan ϕ =

Opposite side h = adjacent side b / 2

h

=

b × tan ϕ 2

F1

= b/2 x b/2 x tan ϕ

F1

=

b 2 × tan ϕ 4

As the angle of repose is limited and in most of the cases it is 150 therefore, F1 = 0.067 b2

……………….I

To prevent the fall of the material below the belt, b = 0.9B - 0.05 equation I

F1 = 0.067 ( 0.09B - 0.05 )2

CONVEYING CAPACITY Volumetrit Capacity, Qm = F1 x V x 3600 = 0.067 ( 0.9B - 0.05 )2 x V x 3600 Qm = 240 V ( 0.9B - 0.05 )2 m3/hr.

DOMHS

71 Qt = Qm x γ tons/hr where, = Specific weight or bulk weight of material in tons/m3

γ

The width of the belt depends on the material handled. For individual loads free margins between 50 to 100 mm wide must be provided on either side of the belt. For a Bulk material, the width is calculated by the formula, B=

Qt / Kv γ

where, K = flowsbility factor = 0.85 to 0.95 --- Plain belt = 0.75 to 0.85 ---- Cleated belt 2) TROUGHED BELT CONVEYOR : (FIG 11 b & c )

FIG 11 : CROSS-SECTIONAL LOADING OF BELT CONVEYOR (a) FLAT BELT : (b) AND (c) TROUGHED BELT WITH THREE AND FIVE TROUGHING IDLERS.

DOMHS

72

Let,

ϕ = material inclination angle or angle of repose

F = F1 + F2 = 0.122 ( 0.9B - 0.05 )2

m2

CONVEYING CAPACITY Volumetric Capacity, Qm = 440 x V x (0.9B - 0.05)2

m3/hr

Conclusion The capacity of Troughed Belt Conveyor is nearly double the capacity of Flat Belt Conveyor. We can increase the capacity of Trough belt by increasing angle of material inclination ϕ but as ϕ increases the life of belt decreases. ϕ = 200 is the most economical angle used in actual practice. Actual Capacity

m3/hr

Q = Qm x K

where, K = Sliding back factor of the material. It depends upon the inclination of the belt. For dry powder or granular material K is given by, Angle of Inclination ( β 0 )

K

20

1

40

0.99

60

0.98

80

0.97

100

0.95

120

0.93

14

0

0.91

160

0.875

180

0.85

200

0.81

220

0.76

240

0.71

26

0

0.66

280

0.61 DOMHS

73 300

0.52

The Belt inclination angle β 0 is seldom kept more than 302. It is normally between 120 and 220. Above this it is not economical to use the conveyor. Capacity in tons/hr Qt = Q x γ where,

γ = Specific weight of material tons/m3 MATERIAL

γ (tons/m3 )

Coal

0.8 - 0.9

Concrete

1.8 - 2.2

Coke

0.4 - 0.5

Lime stone

1.6 - 2.0

Sand

1.4 - 1.5

Iron ore

2.1 - 3.1

NOTE : For an unsized material the minimum width of the belt is B = 2 x amax + 200 mm and for a sized one B = 3.3 x amax + 200 mm, where

a = average lump size in mm.

POWER REQUIREMENT OF BELT CONVEYORS :The Power requirement of a belt conveyor consist of the power required to lift the load to a given height and that for moving the load horizontally. When a Conveyor with a capacity Qt in tons/hr lifts the load to the height H, the required power in KW is given by,

N vertical =

Qt × 1000 × H (KW ) 3600 × 102

=

Qt × H (KW ) 367

where, H = height to which material is raised. In moving the load horizontally the power requirement depends on the frictional resistance to the movement of the belt which varies directly with the capacity Qt and the belt length L. Hence the Power in KW can be determined from, DOMHS

74

N horizontal =

Qt × 1000 × L ⊂ ×Co (KW ) 3600 × 102

=

Qt × L ⊂ × Co (KW ) 367

where, Lc = corrected length = 1.08 x L Co = Specific friction factor Indicating the frictional resistance which has to be overcome in moving 1 ton through 1 meter. Type of Belt

Co

i) Flat Belt slider type

0.15

ii) Plain Belt

0.02

iii) Average antifriction bearing

0.065

iv) High Grade bearing

0.050

⇒ N

= Nvertical + Nhorizontal

=

Qt × H Qt × Lcx Co + (KW ) 367 367

NOTE : If the Power required is in H.P., than the conversion factor is 1 H.P. = 0.736 KW

⇒ N vertical =

Qt × 1000 × H (H .P .) 3600 × 75 =

⇒ N horizontal =

Qt × H ( H .P.) 270

Qt × 1000 × L ⊂ × Co ( H .P .) 3600 × 75 =

Qt × L ⊂ × Co ( H .P.) 270

therefore,

⇒ N = N vertical + N horizontal =

Qt × H Qt × L ⊂ × Co + ( H .P.) 270 270

DOMHS

75 CONVERSION OF H.P. IN TERMS OF BELT STRESSES :

We know, T tight = Tension on tight side T slack = Tension on slack side T sight = T slack = Effective Tension Now, H. P. =

T tight − T slack ×V − −I 75

T tight = e fa T slack

- - II

Where

α is the angle of wrap of the belt, rad ; f is the coefficient of friction of the belt on the pulley ; efα is the traction factor characterizing the tractive performance of the drive pulley. The above relationship assumes that no belt slip exists. For, Rubber pulley and rubber belt combination f = 0.35 Metal pulley and rubber belt combination

f = 0.25

DIMENSION OF BELT :

Let, b = Breadth of belt t = Thickness of belt n = No. of piles present in belt.

fs

= Working Stress in Kg/m2

We know, T max = T sight = t x b x fs For n number of piles, T max = n x t x b x f s

DOMHS

76

Material

fs

1) Cotton

5.4 – 11

2) High Grade Cotton

15 – 30

3) Nylon, Rayon

30 – 100

4) Teflon

125

5) Steel Wire

150 - 300

PROBLEM :-

Design a Flat belt Conveyor for conveying concrete from concrete mixing plant. Site distance between two ends is 100m. Capacity required is 30 ton/hr. Take, Co = 0.065 , f = 0.25 , a = 265 o , Velocity of conveying should not exceed beyond 20 m/sec. SOLUTION :

Given, Co = 0.065 , f = 0.25 , a = 2650 , L = 100 m , Q = 30 ton/hr , v = 20 m/sec. We know, ⇒ Nhorizontal =

Qt × 1000 × Lc × Co ( H .P .) 3600 × 75

30 × 1000 × (1.08 × 100) × 0.065 3600 × 75

=

= 0.78

T tight T

= e fα

slack

ƒα

T sight = T slack e

= e0.25 x (265 x π /180) x T slack T tight = 3.177 x T slack

……………….. (I)

Also, H. P. =

T

tight

−T 75

slack

×V

DOMHS

77

0.76 =

T

−T

tight

slack

75

× 20

T tight – T slack = 2.92 ------------- II Eqn. I & II ⇒ T tight = 4.26 kg T slack = 1.36 kg Since, T max = T tight = t x b x ƒs 4.26 = 1 x b x 6 (assumed ) ⇒

b = 0.71 m

But we know that, b = 0.9B – 0.05 Qm = 240 V ( 0.9B – 0.05 )2 = 240 x 20 x ( 0.71 )2 = 2419.68

m3 / hr.

Qt = Qm x γ = 2419.68 x 2.0 = 4839.36 tons/hr since for concrete

γ = 1.8 – 2.2

REVIEW QUESTION :Q.No.1 : Explain the construction and working of Belt Conveyor with neat sketch? Q.No.2 : Compare Flat Belt Conveyor with Troughed Belt Conveyor ? Q.No.3 : Give the field of application of Belt Conveyor ? Q.No.4 : What are the different types of Drives used for Belt Conveyor ? Q.No.5 : What are the different methods of maintaining Belt Tension? Q.No.6: How will you optimize cross-sectional area of the belt conveyor supported on two roller system ? Q.No.7 : Why hold back devices are necessary in Horizontal and inclined Belt conveyor ?

DOMHS

78 Q.No.8 : What are the different arrangements used to provide the troughed shape to belt in Belt Conveyor ? Q. No.9 : How Conveying Capacity of Belt Conveyor can be calculated ? Q.No 10: A Belt Conveyor system is to be used for conveying coal in Thermal Power station through a distance of 15 meter. The quantity of coal to be handled is 12 t/hr. Take Drive factor = 0.54, Specific friction factor = 0.025, Reduction ratio = 1:20. Determine, (I) Motor HP required (II) Effective tension in Belt (III) Tension in Tight and Slack side ? Q. No.11 : (a) Explain the types of belt conveyors ? (b) Design a belt conveyor for conveying coat from mine site to the railway loading station which is situated at 75 meters from source capacity required is 35 tonnes/hour. And conveying velocity should be up to 15 m/sec. Consider Co = 0.09 φ = 2650 and µ = 0.25 Q.No.12 : (a) Explain working of three different types of take ups used in belt conveyor ? (b) Classify belt conveyor in detail ? Q.No.13 : (a) Find out actual conveying capacity of the throughed belt conveyor used for conveying coal A of a specific weight of 1.2 tonnes ? /m3 width and velocity of belt is 400 mm and 1.5 m/sec respectively. Sliding back factor = 0.85 (b) What are different drives used for belt conveyor ? (c) What are different arrangements of providing the trough shape to the flat belt ? Q.No.14 : (a) Explain in detail the screw conveyor with reference to (i)

construction

(ii)

Typical screw configuration

(iii)

Characteristics

Q.No.15: (a) Explain any one method of maintaining belt tension ( Belt take up ) with neat sketch. (b) Explain construction and working of belt conveyor with neat sketch ? Q.No.16: (a) Compare Flat belt conveyor with trough belt conveyor ? (b) How conveying capacity of belt conveyor can be calculated ? (d) A belt conveyor system is to be used for conveying coal in thermal power station through a distance of 15 meter. A quantity of coal to handled is 12 tones/hr. Take drive factor = 0.54 specific friction factor = 0.025 Reduction ratio = 1.20. DOMHS

79 Determine (I) Motor HP required (II) effective tension in belt (III) tension in light and slack side. Q.17: (a) What are different method of maintaining belt tension ? (b) How will you optimize cross sectional area of belt conveyor supported on two roller system ? How cross sectional area is calculated in case of three roller systems ? On what factor it depend ? (c) Explain fields of application of belt conveyor ? Q.18 : (a) Why hold back devices are necessary in horizontal and inclined belt conveyor ? (b) Explain working of two roller belt conveyor system and give its application ? Q.19 : (a) Discuss the importance of proper belt tension in different types of conveyors. (b) Describe the procedure for determining the power requirement and salient dimension of belt conveyor ? Q.20 : (a) Find out the conveying capacity of troughed belt conveyor used for conveying wheat having a specific weight of 1-1 tonnes/m3. Actual width of belt is 600 mm and speed should not exceed 2.8 m/sec. Sliding back factor is 0.85. Q.21 : (a) A belt conveyor is used for conveying the raw material to a mixing plant in a cement factory. The distance between the raw material store a mixing plant is 120 metre and material is to be conveyed at an inclination of 10. The width of belt is 100 cm and the rate of conveying required is 40 tonnes/hour. Calculate (1) H.P. required to drive the conveyor. (2) Tight side belt tonsion Slack side belt tension. Effective belt tension. Assume

Specific friction factor = 0.065 Coefficient of friction = 0.25 Angle of wrap

= 2100

Angle of repose format = 180 Q.22 : (a) Explain limitation and application of belt conveyor ?

DOMHS

80

SECTION-B UNIT – IV Types of Cranes and their application. Electric Overhead Traveling (E.O.T.) cranes. Types of E.O.T. Cranes and their application, Design of Mechanical System used for, a) Cross Travel of the Crane. b) Longitudinal Travel of the Crane and c) Hoisting and Lowering motion of the Crane load. Design of Breaking System for various of E.O.T. Cranes, functions of limit Switches used in E. O. Cranes.

( 13 Marks )

CRANES :-

CRANES are employed for lifting and lowering bulky items and packages or cases. They provide overhead movements. The crane hook can move in a rectangular area (Overhead Bridge Crane) or a circular area (Jib Crane). An Overhead Bridge Crane finds application in most of the industries, making engines, compressors, pressure vessel, foundries, steel mills, Power House, Chemical Plants, etc. A Jib Crane (FIG 12) is preferred where lifting of the jobs is required in a few locations only or where bridge cannot be erected; for example, outside near the wall of building. In a jib crane the hoist unit may be mounted on an I – section Jib which is in turn supported on a column. A Gantry crane (FIG 13) acts as am auxiliary to Bridge Crane. It is on wheels and can be moved at the place of use.

bracket

HINGE

trolley with hoist wall bracket

FIG 12. JIB CRANE

DOMHS

81 TYPES OF CRANE AND THEIR APPLICATION :-

Cranes are classified as, A. Stationary Rotary Cranes

a. Jib Crane (employed in assembly shop and machine tool shops as a means of transferring the work from station to station ) b. Pivotted Post Crane (lifting the material which are in close proximity of Post ) c. Fixed Pillar Crane ( Use in machine tool shop as work positioners) d. Derricks Crane (Loading or railroad, flat car, and lorries, for handling work piece at machine tool shops, for construction site work, etc ) B. Cranes on rails

a. Ceiling Mounted Cranes (where the handling space is a critical area and the material handling may interfere the production process on shop floor ) b. Monorail Cranes ( A monorail is a single beam overhead track whose lower flange serves as run-way for the trolley mounted Hoist.

It is used for following up

predetermined path carrying a series of trolley through various processing or assembly ) c. Trackless Cranes (where the path of the material to be handled is not fixed ) d. Locomotive Crane i)

Railway Crane (handling of bulky metal structure )

ii)

Crawler Mounted Crane (Equipment of this kind is a convenient tool for mechanizing Handling Operations and erecting jobs of various character.)

e. Electric Overhead Traveling (E.O.T.) or Bridge Crane i)

Single Girder Cranes

ii)

Double Girder Cranes

iii)

Gantry Cranes (A typical application is the handling of pre-fabricated reinforced concrete units of considerable bulk at sites of big thermal and nuclear power station.)

Depending on the mounting of the Hoisting Mechanism E.O.T. Cranes are classified as, i) Under-Running Bridge Cranes.

ii) Top-Running Bridge Cranes

ELECTRIC OVERHEAD TRAVELING CRANE OR OVERHEAD BRIDGE CRANE :-

The most widely used industrial crane are Overhead Bridge Crane. They provide Overhead Movements. In this Crane all the mechanism like lifting, traveling, are mounted on the trolley and DOMHS

82 the trolley is placed on a Bridge. The bridge is located suitably at elevated distance. The Crane hook is suspended towards ground which can move in a rectangular area. Since Overhead Bridge Cranes travel on elevated tracks, they occupy no shop floor area and are consequently very convenient in operation. Overhead Bridge Crane of Push-type are operated by hand, other cranes of this kind are operated electrically. General purpose Overhead Bridge Crane manufactured, have a capacity ranging from 5 to 300 ton, and Special purpose 600 ton have been developed to handle erection work at sites of big nuclear and hydro-power projects. Depending on the mounting of Hoisting Mechanism and Trolley, E.O.T. Cranes are classified as, A.UNDER-RUNNING BRIDGE CRANE (FIG 14) :

In this type of Crane, the lifting element is suspended on a I-beam or it is mounted at the bottom of the bridge. Under-Running Bridge Crane can be operated in buildings of a height less than would have been required for Top-Running Cranes. Another advantage is that Under-Running Bridge Crane can transfer loads from bay to bay. Under-Running Bridge Crane are weightless and required less held room as compared to the Top-Running Bridge Cranes. They also permit better space utilization. However lifting capacity is limited in this Crane. Normally Under-Running Bridge Crane are used up to 5 to 6 tons of load or maximum 10 tons load. Under-Running Bridge Crane are controlled from the cab which is suspended from either the bridge or the trolley. Low speed Crane are Crane control is selected in each particular cases taking in to account shop equipment layout, crane traveling speed and the availability of means for the transfer of loads from bay to bay.

DOMHS

83

I-BEAM

WHEEL TROLLEY + HOISTING MECHANISM

ROPE

HOOK

FIG.NO.14 UNDER RUNNING BRIDGE CRANE

B. TOP RUNNING BRIDGE CRANE (FIG 15)

This Crane essentially consist of a bridge traveling on wheels fitted to the end carriage and supported by track rails which, in their turn, are fixed to supports provided either at the top of the shop walls or column. A trolley or crab equipped with a hoisting mechanism which Hoists or lowers a hook or grip of some kind travels along the top flanges of the bridge as shown in Fig 15.

WHEEL TRACK RAILS

FIG NO. 15 TOP RUNNING BRIDGE CRANE

DOMHS

84 They are suitable for heavier load and are available in wide range of capacity up to 1000 tons. If the trolley of the Crane is supported on the bridge having one horizontal girder it is known as Single Girder Crane. Single Girder Cranes are used for 10 tons load. For heavier load bridge with two girder is used and it is known as Double Girder Crane. COMPARISON :

Under-Running Bridge Cranes compares favorably with Top-Running ones in point of mass. So a 5 ton capacity Under-Running Crane weights 4.3 tons against 8.5 tons of Top-Running Crane having the same capacity. CHARACTERISTICS :

1. Covers any spot within the rectangular area over which the Bridge travels. 2. Can be provided with “cross-over” to adjacent bay. 3. Provides three dimensional travel. 4. Hoist may be top or bottom running. 5. Bridge propelled by hand, chained gearing or power. 6. Two hoist (light and heavy duty) can be mounted on one Crane. 7. Usually designed and built by special companies, 8. Does not interfere with work on floor. 9. Can reduce axile Aisle space requirement. 10. Can reach area otherwise not easily accessible. 11. Crane ways can extend out of the buildings. USES :

Overhead Bridge Crane can be used for, 1. Low to medium volume. 2. Large, heavy and awkward objects. 3. Machine shops, foundries, steel mills, heavy assembly and repair shops. 4. Intermittent moves. 5. Warehousing and Yard storage. 6. With attachments such as magnets, strings, grabs, buckets, etc. LIMITATIONS :

1. Capacities to 1000 tons. 2. Spans to 125 fts. DOMHS

85 3. Bridge speed from 200-500 ft/min. 4. Hoist speed to 80 ft/min. 5. Movement is relatively slow. 6. Expensive. 7. Confined to area covered by craneway. 8. Heavy frame work requires to support ways. 9. Usually requires an operators in cab – sometimes 1 or 2 hookers. LOAD HANDLING ATTACHMENTS :-

Depending on application, used in conjunction with Overhead Bridge Crane, are Handling Attachments of various kinds, viz , A. Hooks

Hooks are multi-purpose Handling attachments widely used in hoisting installations. The load is suspended from the hook by means of slings made of hemp ropes or chains. Alternatively, the load can be picked up by a grab suspended from the hook. Depending on the shape, Hooks are of following types. a. Ordinary pattern Hooks

b. Ramshorn Hooks

&

c. Traingular Hooks

The two first-named come in standard sizes so shaped as to have a uniform design at the minimum of weight. B. Lifting Magnets

Operating on direct current, lifting magnets are widely used in handling steel and cast iron loads. a. Circular Magnets b. Rectangular Magnets C. Tong Type Grab

When unit loads of given shape and size are to be handled, considerable saving in time and labour can be effected by employing special grabs suspended from the crane hook which grasp and release the load at almost no time. Varying in design with the shape and properties of the load handled, grabs are constructed to be reliable, compact, lightweight, convenient and safe. Depending on the mode of operation they can be classed as, a. Self-closing b. Automatic DOMHS

86 D. Plate Clamp

This Handling Attachment is an eccentric clamp used for handling steel sheets and plates in the vertical position suspended from the Hook. E. Vaccum Lifters

These end of line attachements offer a convenient means of handling sheet stock of various kind (steel, non-ferrous metals, glass, etc.) along with cartoons, boxes, etc.) F. Grabbing Attachment for Bulk Material

a. Ladles b. Buckets c. Grab Buckets or Clamp Shell Buckets Automatic picking up of the loads, high-tonnage loads in particular, is affected through the use of Automatic Handling Attachments called Grab Buckets or Clam Shell Buckets. G. Special Grip

Wire, ropes and chains for Hoisting and Haulage. PARTS OF E.O.T.CRANE :A. BRIDGE :

Bridge is made up of standard rolled section or by handling steel plate in bar section. Bottom of the Bridge is provided generally with four wheels which moves over the track rails. At the top portion of the bridge, trolley is mounted. B.TROLLEY :

It is structure on which lifting mechanism of the crane is mounted. Accommodated on the trolley frame are the main and auxiliary hoists along with the cross traverse mechanism. Trolley moves on the bridge by means of wheels. Separate motor is provided for movement of the trolley on the bridge i.e. Cross travel of the crane. C. DRUM AND SPROCKET ASSEMBLY :

It is mechanism mainly responsible for lifting the load. It is mounted on trolley drive transmission system. It consist of various transmission element used for achieving different movements of the crane. Overhead Cranes have got three important movements viz, system of load, movement of bridge i.e. longitudian travel, movement of trolley i.e. Cross travel. First drive is for providing power to rope drum, second one is for bridge movement, and the third one for

DOMHS

87 trolley movement. Next is hook and rope. Hook is suspended from rope by means of flexible wire rope, which is generally made of steel. D. BRAKE :

It is very essential part of the Crane used for restricting various movements of the Crane like brake for rope drum, brake for movement of trolley. Types of Brakes :

1. According to construction a. Block Brake b. Band Brake c. Disc Brake (Thrust Brakes) d. Cone brake (Thrust Brakes) 2. According to Principle of operation a. Automatic Brake b. Controlled Brake 3. According to function a. Stopping Brake b. Regulating Brake 4. Method of applying Brake Force a. Normally set Brakes b. Normally release Brakes c. Combination Brakes FUNCTION AND TYPES OF LIMIT SWITCHES USED IN E.O.T.CRANES :FUNCTION :

i)

Excessive Trolley travel are checked by Limit Switches.

ii)

Weight Displacement are controlled by limit switches.

iii)

Limit Switches are used for breaking the power supply.

TYPES :

Limit Switches are classified as, A. Inductive type of Limit Switch B. Controlling type of Limit Switch a. Stopping DOMHS

88 b. Starting c. Reversing C. Interlock type limit switch Limit Switches can be further classified as, D. Mechanical E. Electrical F. Pneumatic DESIGN OF MECHANICAL SYSTEM USED FOR E.O.T. CRANE :A . HOISTING AND LOWERING MOTION OF CRANE LOAD OR DESIGN OF HOISTING EQUIPMENT (FIGURE 16) :WORM WHEEL DRIVER PULLEY

TRANSMISSION LINK DRIVE PULLEY

ROPE

FIG NO.16

It consist of following parts. a) Prime Mover b) Transmission link between driving and driven pulley of shaft c) Drum for collecting rope d) Flexible hoisting equipment like rope or chain e) Brakes f) Load Handling Attachments like Hooks, grabs, etc. DOMHS

89 Hoisting Mechanism may be Hand operated or Power operated, but in E.O.T. Crane it is normally Power operated. 1. Calculation of Power required : H −P=

Q ×V 75 × η

2. Calculation of Torque : H −P= ⇒T=

2Π NT 4500

H .P. × 4500 2Π N

3.Calculation of speed ratio : SPEED RATIO =

N motor N drum

4.Calculation of Linear Velocity : v=

ΠDN m / sec 60

where, Q = Load to be lifted, T = Torque. V = Velocity in m/sec, Nmotor = Speed of Motor shaft. η = Efficiency of mechanism, Ndrum = Speed of Rope Drum. N = Speed in R. P. M. , D = diameter of Rope drum. B. DESIGN OF CROSS TRAVEL OF E.O.T. CRANE (FIGURE 17)

TROLLEY

BRIDGE

HOOK

FIG NO. 17

DOMHS

90 A. CALCULATION OF LOAD ON WHEEL :

i) If the Hoisting equipment is placed exactly at the center of the Trolley. (FIGURE 17 a i ) Q

FIG.NO. 17a (i)

P max =

Go Q + 4 4

2) The hoisting mechanism may be at eccentric position

Q

A

FIG NO. 17a (ii)

Load on side A =

Q × b2 2×b

Load on side B =

Q × b1 2×b

Pmax =

Go b2 +Q× 4 2b

DOMHS

91 B.CALCULATION FOR THE RESISTANCE TO MOTION OF TROLLEY WHEEL:

F

W F

FIG NO.17b

When wheel is traveling in horizontal direction it has to overcome certain resistance owing to the weight of the trolley and friction taking place. Take friction of wheel contact and surface as ωMoment of Resistance , M=ωR = (Q + Go)

µd 2

+ (Q + Go) K

therefore, Resistance to motion. ω=

(Q + Go )

( µ d + 2K) 2R

C. POWER REQUIRED : H −P=

F ×V ωv = 75 × η 75 × η

D. SPEED RATIO : SPEED RATIO =

& Ntrolley = where ,

N motor N trolley

60 V ΠD

V = Linear velocity of the trolley D = diameter of Trolley wheels

DOMHS

92 E. TORQUE REQUIRED : H.P. = ⇒T=

2ΠNT 4500

H .P. × 4500 2ΠN

NOTATION, Go = Weight of the Trolley & Hoisting equipment etc. Q = Load to be lifted Pmax = Maximum load on each wheel d = diameter of axis D = diameter of wheel R = radius of wheel K = coefficient of rolling friction at wheel contact ƒ = Coefficient of friction for bearing ω = frictional forge or resistance to motion of the wheel C. DESIGN FOR LONGITUDINAL TRAVEL OF E.O.T. CRANE (FIG NO.18) :-

a. CALCULATION OF MAXIMUM LOAD ON THE WHEEL :P max =

G / 4 + (Go + Q) ( L − e) 2L

b. RESISTANCE TO MOTION OF WHEEL : ω =

(Q + Go + G ) (fd + 2K) 2R HOISTING EQUIPMENT TROLLEY

WHEEL

RAILS

FIG NO.18

DOMHS

93 c.POWER REQUIRED : H.P. =

ω ×v 75 × η

d. TORQUE REQUIRED : H .P. = ⇒T=

2ΠNT 4500

H .P. × 4500 2ΠN

e. SPEED RATIO =

Nmotor Nwheel

NOTATIONS Go

=

Weight of Trolley

G

=

Weight of Crane or Bridge

Q

=

Weight to be lifted

L

=

Span or Length of the Bridge

e

=

Maximum extreme possible position of the trolley

V

=

Linear velocity if the Bridge

D

=

diameter of wheel of Bridge

µ

=

Coefficient of friction at bearing i.e. at wheel shaft and bearing

k

=

Coefficient of friction between wheel of bridge & Rails.

DOMHS

94 REVIEW QUESTION :

Q.No.1: How will you design the Hoisting Mechanism of Crane ? Q.No.2 : Explain the constructional detail of E.O.T. Crane and it’s working with neat sketch ? Q.No.3 : Sketch and explain the system used for longitudinal travel of E.O.T.Crane ? Q.No.4 : Explain Limit Switches and its function in E.O.T. Crane? Q.No.5 : Explain with the help of neat sketches the material handling attachments used in E.O.T. crane for handling the liquid metals ? Q.No.6 : What do you mean by E.O.T. crane ? Giving classification specify their field of application ? Q.No.7: What are the precautions to be taken while operating E.O.T. crane? Q.No.8 : Give advantages and application of E.O.T. crane ? Q.No.9 : (a) Sketch the mechanical system used for longitudinal travel of the crane and explain its working. (b) Explain different types of E.O.T. Cranes and give at list two application of each of them. Q.10 : (a) Design a cross trolley mechanism of a E.O.T. crane for lifting the load of 7 tones where weight of trolley is 1.2 tones velocity required for cross traverse is 12 m/min. When the dia.of wheel is 12 cm. Take coefficient of friction for bearing is 0.01, coefficient of friction for bearing is 0.01, coefficient of friction between wheels and rails is 0.05. Diameter of axel is 25 mm. Assume efficiency of mechanism as 75 %. (b) Explain construction and working of overhead crane in a foundary shop to handled heavy castings ? Q.11 : (a) What is breaking of E.O.T. crane ? Why it is necessary ? (b) Explain in details various parts of E.O.T. crane ? Q.12 : Explain with neat sketches various load handling attachments used in E.O.T. crane ? Q.13 : (a) Explain in details the working of under running bridge crane ? (b) Explain in details the working of top running bridge crane ? Q.14 : (a) Explain the design procedure for (i)

hoisting and lowering mechanism of crane DOMHS

95 (ii)

cross travel of crane

(iii)

longitudinal travel of crane

(b) Explain drum and socket assembly used in E.O.T.crane ? Q.15 : (a) Discuss various types of cranes and their application. (b) What are the precautions to be taken while operating E.O.T. crane ? Q.16 : Explain with neat sketches working of longitudinal travel crane ? Q.17 : (a) Give the factor of designing the breaking system in E.O.T. crane ? (b) What are different cranes. Explain working of overhead crane ? Q.18 : Explain ‘ load operated breaking system’ used in E.O.T. crane ? Q.19 : Sketch the mechanical system used for longitudinal travel of the crane and explain its working ? Q.20 : (a) Describe hoisting and lowering motion crane. Explain its working principle. (b) How cranes are classified ? Give the characteristic of overhead cranes ? Q.21 : (a) Compare the underslung and top mounted E.O.T. crane ? (b) Explain longitudinal and cross traversing mechanism used in E.O.T. crane ? Q.22 : (a) An electric traveling crane can lift the load of 20 tonnes at hoisting speed of 12 meter per minutes. The brake drum of crane is 55 cm. diameter. The maximum distance traveling by the crane is 100 meter. If the speed of electric motor is 1440 r.p.m. efficiency of mechanism is 0.8. Calculate (i)

H.P. required to drive the motor ?

(ii)

Available torque at brake drum

(iii)

Speed reduction ratio ?

(b) What is Tib crane ? What are its application OUR OTHER PUBLICATION OF YOUR INTEREST IS ON MEASUREMENT SYSTEM VISIT US AT http://business.vsnl.com/siddhivinayak_akola MAIL US AT: [email protected] For notes contact at: SIDHHIVINAYAK COMPUTERS, RENUKA NAGAR, DABKI ROAD,AKOLA -6 0724-422684

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96

UNIT – V Introduction , Working Principles, and field of application of the following Mechanical Handling Equipment ( No. Mathematical treatment is contemplated ) a) Pneumatic Conveyors. b) Hydraulic Conveyors. c) Escalators. d) Robots in Material Handling. (13 Marks) PNEUMATIC CONVEYORS :-

Pneumatic Conveying is a method of transporting bulk materials in the form of powder, short fibre and granules over a pipeline as a mixture with air or due to a pressure of air. In either case a high-velocity air stream is used to impart motion to the material. Such an installation will convey over more than 2 km at a rate of up to 400 tons per hour. It is capable of lifting loads to a height of 100 metres. Three basic system are used to generate, the high-velocity air stream : 1. SUCTION OR VACUUM SYSTEMS : (FIG 19a)

It utilizes a vacuum created in the pipeline to draw the material with the surrounding air. Referring to Fig, a positive pressure exhauster 6 causes material to flow through a nozzle 1 and a duct 2 into a cyclon collector 3 where it is separated from the conveying air. The exhaust air is fed to a filter collector 5 for complete recovery of fine material, leaving then through the exhauster into the atmosphere. The material is discharged from the collectors through rotary air-lock feeders 4 preventing in leakage of air. Vacuum conveying eliminates the dust problem and is most successfully applied for unloading material at a number of points, using a network of pipes, and delivering it to a single point. The system operates at a low pressure, which is practically 0.4 to 0.5 atm below atmosphere, and is utilized mainly in conveying light free-flowing materials over short distances ( e.g., bulk carrier unloading ). 2. PRESSURE-TYPE SYSTEMS : (FIG 19 b)

In this, a positive pressure is used to push material from one point to next. Material is introduced into a pipeline 2 (FIG

) through a rotary air lock feeder 10 to be conveyed by

transport air fed by a blower 7 through a receiver 8 and a moisture trap 9. At the destination, the air stream enters a cyclon collector 3 for the recovery of material and the exhaust air is passed DOMHS

97 through a filter collector 5 for dust separation before leaving into the atmosphere. The system is ideal for conveying material from one loading point to a number of unloading ones. It operates under a pressure of 6 atm and upwards and is capable of handling heavy pulverized and lumpy materials over considerable distances.

FIG NO.19 PNEUMATIC CONVEYORS (a) SECTION OR VACUUM SYSTEM (b) PRESSURE TYPE SYSTEM 3. COMBINATION SYSTEMS OR PULL -PUSH SYSTEM :

In this, a suction system is used to convey material from a number of loading points and a pressure system is employed to deliver it to a number of unloading points. Such installations are utilized when conveying over a long distance is required. The pressure differential in the pipeline created by the blower of a pressure system or by the exhauster of a suction one must be sufficiently high to accelerate the mixture of air and material to a velocity required for the functioning of the system. Pneumatic conveying is possible when the velocity of the air stream is greater than the soaring velocity Vs of the material. This, in DOMHS

98 its turn, is a velocity at which the aerodynamic forces acting on a particle are at balance with its force of gravity so that the particle is capable of soaring in the pipeline. The soaring velocity depends on the weight and shape of the particle and is determined experimentally, taking into account the form drag. ADVANTAGES :

Pneumatic conveying enjoys wide-spread application, apparently due to the following advantages offered : 1. Delivery of materials over a path capable of changing its direction in any plane as required, 2. Processing of the material simultaneously with its conveying, 3. An almost limitless number of loading and unloading points served by a single system, 4. Air and gas tightness eliminating dust nuisances and dust hazards , 5. An almost totally automated conveying 6. Considerable reduction in of losses of material. 7. Improved labour conditions, 8. Minimum of Human attendance. LIMITATIONS :

1. High Power requirement, 2. Rapid wear of equipment, 3. The problem of dust recovery from the exhaust air before this leaves into the atmosphere, 4. Inability to convey wet, caking and sticky loads. HYDRAULIC CONVEYORS :-

Coming under the category of pipeline conveying are Hydraulic Conveyors in which bulk material in the form of slurry is transported over tubes. In existence are three methods of conveying : A SLUICING :

In this slurry is conveyed over sluiceways at a slight down gradient ( 0.02-0.06) due to gravity.

DOMHS

99 B. PUMPING (FIG 20 a) :

When a solid pump 3 draws slurry from a mixing pit 1 and delivers it over a pipeline 4. At the destination, the material is recovered from the stream by means of a mesh filter 6, being then dumped into a hopper 7, and the water is drained into a settling tank 8 from which it is returned to the mixing pit by a recirculating pump 5. The systems operates at inclines of up to 90 deg as well as on horizontal sections. C. SLUICING AND PUMPING (FIG 20 b) :

When the slurry is Gravity-fed over a shop sluiceway 10 into the collecting hopper 12, of a jet pump 13 which introduces it into a pipeline 9 through a diffuser by means of a highvelocity jet of water supplied by a pump 11. Hydraulic conveying has firmly gained ground in conjunction with Hydraulic stripping and is of particular value when wet concentration is employed.

FIG NO.20 HYDRAULIC CONVEYORS (a) PUMPING (b) SLUICING & PUMPING ADVANTAGES :

1. The chief asset of Hydraulic conveying is the possibility of transporting materials over long distances, literally anywhere a pipeline can placed, at a high rate without mechanical means along the path. DOMHS

100 2. Operating automatically, it poses no problems in service and enables transportation to be combined with certain processing operations. LIMITATIONS :

1. The nature of the load handled. 2. The size of the particles. 3. Rapid wear of the parts in contact with slurry. 4. Comparatively high power consumption prevent hydraulic conveying from use on a more wider scale. POWER REQUIREMENTS :

The water used as the propelling medium can be disposed of into a stream, provided it has been clarified in a treatment plant. A more practical and economical way requiring neither a water treatment plant nor a substantial supply of water at hand is the re-circulation of the water its use. In either case, the power requirements of a Hydraulic Conveyor in KW can be estimated by a formula, N = γo

V ×H 367 × η × µ

Where, γo is the density of water in Kg/1 ; V is the volumetric capacity in m3/h ; H is the total head in m (equals to the loss of head in both the suction and delivery lines) ; η is the efficiency of centrifugal pump; µ is the solids concentration factor indicating the ratio between the content of solids by volume to the total volume of slurry:

µ=

1 1+ β

where β is the ratio of water to solids by volume. It is good practice to keep the value of µ as high as possible. An increase in the specific gravity from 1.1 to 1.2 brings about a two-fold increase in the capacity while the power requirement increase only by 9 percent to provide for a higher head. Most Hydraulic Conveyors are adopted to convey slurry at a concentration consistent with the critical velocity which is one providing for the conveying of the material at its maximum concentration without settling along horizontal sections of the pipeline.

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101

FIG NO.21 ESCALATORS ESCALATORS (FIG 21) :-

Chain conveyors specially adopted for the vertical transportation of people are termed Escalators. An escalator is an inclined conveyor with the driving traction element in the form of steeps 1 attached to step-drive chains 2. Each escalator step is carried on four wheels riding on tracks. Escalators are widely used in undergrounds, department stores, and other public places.

They operate at speeds between 0.5 and 1 m/s depending on the requirements.

Underground installations are commonly run at 0.7 to 0.95 m/s but in applications with a lower rise the speed is lower (0.5 to 0.6 m/s ). To provide for the safety and comfort of passengers, escalators are designed to accelerate at starting at not more than 0.6 m/s2 with an increase up to 0.75 m/s2 during the rest of the starting period. Escalator capacity, i.e., the number of persons to be calculated by the formula Q = 3600

nv ϕ tstep

Where tstep is the spacing of steps in m ; n is the number of passengers per step ; v is the step speed in m/s ;

DOMHS

102 ϕ is the stairway capacity factor. Experimental studies have revealed that ϕ = 0.6 (2-v). It indicates that the capacity factory varies with the step speed and has direct bearing on the escalator capacity along with the speed. In this country, all escalators operate at an incline of 300. They are designed to meet stringent requirement in point of the strength and wear resistance of the drive operating, at a rule, continuously at high duty factor throughout the day. A typical Escalator drive 5 consists of an electric motor, reduction units, brakes (service and safety), and couplings. It is supplemented by a standby drive used during inspections and repairs which is geared either to the motor shaft extension at the end opposite to the reducer input shaft. The drive and running gear are designed using the point-to-point method of chain pull calculation in running up and down, empty and loaded. Escalators are always provided with traveling handrails 3-laminated duck structures overlaid with rubber. They travel on guides topping balustrades, being driven by the head sheaves 4 at the top landing. The sheaves are lagged with rubber for traction. Every handrail is provided with a tensioning arrangement 6 on its return run consisting of a fixed bend sheave, a tension sheave mounted on a movable frame, a guide frame and weight. An inherent feature of all escalators are safety devices which bring them at rest in case of a failure or hazard such as, for example, the rising of steps before arriving at the entry and exit comb plates, an increase in speed exceeding rated value by 25%, a sudden reversal of the motor, the de energizing of service brake solenoids or thrustors, and a failure of brakes to be starting. ROBOTS (UNIVERSAL TRANSFER DEVICE) IN MATERIAL HANDLING :DEFINATION :

The Robotic Industries Association’s define Robot as “a reprogrammable multifunctional manipulator designed to move material, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks”. ADVANTAGES :

They have definite advantages for some type of materials handling application, such as DOMHS

103 1. Repetative moving of heavy parts on a fixed cycle over a fixed path, 2. Material handing in dangerous (hazardous), toxic and radioactive atmospheres, and 3. Taking over dangerous, dull, and boring jobs such as punch press operation. 4. Operations involving the handling of heavy or awkward tool or workpart. LIMITATION :

1. They work best in a fixed-motion pattern whether it be a long or short run. 2. Present models are deficient in vision and ability to interpret what is seen. 3. Especially, they lack the judgement human operators posses. CLASSIFICATION :

Robots can be classified depending on the following criterion, A. Technology 1) Low technology Robot 2) Medium technology Robot 3) High technology Robot B. Mechanism 1) Non servo Robot 2) Servo controlled Robot C. Generation 1) First generation Robot (Simple programmable ) 2) Second generation Robot (Capability to understand the environment) 3) Third generation Robot (Intelligent Robot) D. Based on manipulative function 1) Pick and place Robot 2) Special purpose E. Physical configuration 1. Polar coordinate configuration 2. Cylindrical coordinate configuration 3. Jointed arm configuration 4. Cartesian coordinate configuration F. Based on motion characteristics 1)Point to Point Robot DOMHS

104 2) Continuous path Robot ROBOTIC FUNCTIONS IN MATERIAL HANDLING :

A Robot can perform several different type of tasks in the materials handling operations in a factory or distribution center, including : 1. Pick and Place

The Robot picks up an object from a fixed location, moves it to a carefully defined destination, place it in position, and then release it. This series is repeated continuously except for interruptions due to lack of material, parts out of position, or other unusual events. The Robot must be programmed to take appropriate action if any of these irregular event occur. This action may be to stop the system or to complete the cycle empty. This type of action is suited to high-volume mass production. A Robot with only three degrees of freedom in the x, y, and z , axes can be used for the pick and place function. This reduces the capital investment in the Robot and also the expense and difficulty of programming. On the other hand, converting the pick-and –place Robot to another task may be a major undertaking. 2. Palletizing and Depalletizing

Many products cannot be handled by conventional palletizing machine. Their size, shape, and packaging are not suited to conventional palletizers. Palletizing is another example of relatively simple work cycle similar to pick and place. However, it differs since each product item has to go in a different place on the pallet. This requires a longer program but not necessarily one that is much more complicated. The reverse of palletizing is depalletizing. A high-volume product may be received in pallet loads, Manual unloading would be expensive, tiring, and possibly entail an unacceptable damage level. The Robot can quickly and efficiently unload the pallets and move the material to an inbound conveyor or to a storage location. 3. Dangerous Operations

Many industrial situation involve dangerous conditions or toxic materials. A robot can be used for these operations since it is not affected by many hazards and can be replaced in part or whole without injury to a worker if it is damaged. For example, robots can be used in the radioactive section of several nuclear power plants to transfer material and fuel. The radioactivity doesn’t affect the robot’s performance and DOMHS

105 eliminates exposure to radioactivity.

However, the robot does not become radioactively

contaminated once it is exposed and then must be handled as a radioactive object. Another example of a dangerous operation is loading material into a forge or punch press. A Robot can put the part into the press and remove the finished part automatically. Even if an accident to the robot occurs, replacement of the robot part is easy and no human worker is injured. 4. Moving Heavy Objects

Robots can be built to move heavy objects that weigh more than the limit considered acceptable for a human worker. If it has the capacity to handle the weight, the robot can function indefinitely without fatigue or back strain. 5. Loading and Unloading

Robots can be used for general loading and unloading if the motion patterns are within the robot’s capabilities. A major limitation is the area covered and the distance the robot must move the product. Thus, a robot would have difficulty loading a railroad gondola car unless either the car or the robot were repositioned periodically while the robot filled the section within its reach. This work is seldom sought by a manual worker. It is heavy, boring, dull, and seldom leads to a better job. 6. Packaging

A recent application is the use of robots in packaging a product. 7. Inspection

A robot can be used to move product as part of an inspection operation. The robot can pick a unit from a moving assembly line, transfer it to the inspection station, turn it over if necessary, and then put it back on the line if it is good or in the reject pile if it fails to pass inspection. APPLICATION :

In this section, we shall look at a few specific examples of material handling systems that use robots. 1. Press Work

Interest in removing the operator from exposure to injury from punch presses goes back at least 30 years. At that time, some major companies adopted the policy that the press DOMHS

106 operator should put hands into the press to feed or remove the parts. Various transfer mechanisms and guards were developed. However, many were unsatisfactory and led to reduced productivity. Now, a robot can be used to put the material into the press and remove the complete part. Since most of the material is sheet metal, which is stiff and solid, the robot has no difficulty grasping and moving the parts. Furthermore, the robot’s function can be synchronized with the press strokes to improve productivity. 2. Forging

A robot has an additional advantage handling forging billets and parts. It is not affected as much by heat as the human operators. With properly designed grippers, the robot can pick up and carry hot forgings with no trouble or damage. It also has good repeatability, so it can accurately place the billet in each cavity. This reduces scrap losses due to misalignment. 3. Die Casting

Robots can be used to remove the completed die casting from the casting machine. Again they are not bothered by heat. 4. Assembly

A Robot can be used to put and place parts and components in an assembly operation. If the operation is high-volume mass production, the robot can replace the human operator with resulting increase in productivity. 5. Flexible Manufacturing System

The role of robots in a flexible manufacturing system (FMS) is different from its function in most applications. In a typical FMS, many different parts are produced in small batches. Consequently, the robot must be programmed to handle many different items on their way through FMS. TRENDS :

Several trends exist in Material Handling by Robots. Among them are ; 1. Increasing gap between the cost of using a robot and that of a manual worker. The economics of scale, competition, and technological improvements are holding down the cost of robots while their efficiency goes up. On the other hand, the hourly wage increases have exceeded productivity improvement, so that unit cost of manual material handling keeps rising.

DOMHS

107 2. Increased used of robots to load and unload machine tools, Not only do costs go down, accidents decrease. 3. The use of vision sensing will expand. Although present applications are relatively crude, research is producing improvements regularly. 4. The use of electricity for powering robots is increasing at the expense of hydraulic power. REVIEW QUESTIONS :

Q.No.1: Compare Pneumatic and Hydraulic Conveyors on the basis of their working and application. Q.No.2: Explain working of one Hydraulic Conveyor with neat sketch? Q.No.3: What are Escalators ? Explain the working principle of Escalator? Also state its application. Q.No.4: Explain the role of Robot in Material Handling ? Q.No.5: Sketch and explain in detail the three basic systems used to generate the high-velocity air stream in Pneumatic Conveying ? Q.No.6: What is “Industrial Robots”? Give advantages of Robots? Q.No.7: How you find Robots useful in material handling system in mordern industries ? Brief out with suitable examples ? Q.No.8: Describe working principle of hydraulic conveyor. State its application ? (Any one) Q.No.9: (a) Explain in details the suction or vaccume systems of pneumatic conveying. (b) Write short notes on escalators ? Q.No.10: (a) Explain in details the pumping system of hydraulic conveyor ? (b) List out the field of applications of ‘Industrial Robot’. Q.No.11: Explain in details the various types of Pneumatic conveyors with neat sketches ? Q.No.12: Define robots. Give advantages, disadvantages and classification of robots ? Q.No.13: (a) Explain construction and working of Pneumatic conveyor with neat sketches ? (b) What is robot ? What are its general characteristic ? Q.No.14: (a) What are requirement of a satisfactory pneumatic handling system ? (b) What are the different causes of accident ? Q.No.15: (a) Explain preventive measures requires for pneumatic conveying system ? (b) Where and why use conveyor ? What types of material that can be handled by conveyor ? DOMHS

108

Q.14 : (a) Explain the fig the pressure type system of pneumatic conveying ? (b) What is pneumatic conveying ? What are different method used ? Explain them is details with neat sketches? Q.15 : (a) List down the application in robot in industries ? (b) What are limitation of Hydraulic Conveying ?

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109

UNIT -VI A) Introduction, Working Principle and field of application of following mechanical Handling Equipment. (No. Mathematical treatment is contemplated) 1) Ladle Crane 2) Electric lifts. 3) Skip Hoists. 4) Fork Lift Trucks. 5) Winches. B) Repairs and Maintenance of Material Handling Equipment’s and Hazards with Material Handling Equipment. (13 Marks) LADLE CRANE (TEEMING CRANE) (FIG 22) :-

l FIG NO.22 TEEMING CRANE

Depending on the application, used in conjunction with Overhead Bridge Crane are handling attachments of various kinds, viz., hooks, lifting magnets, grab buckets, special grips, etc. Illustrated in fig, is a teeming crane with two hooks and a spreading beam interposed between the hooks to lift a ladle containing molten metal, while the auxiliary hoist with its hook block serves to tilt the ladle in the course of teeming the steel as well to cope with minor jobs.

DOMHS

110 ELECTRIC LIFT (FIG 23) :-

When load are to be hoisted over a given path, use is made of hoisting equipment adapted to lift loads in cars, buckets or on platforms, these traveling vertically or almost vertically over a rigidly-build hoistway.

The load trajectory in such hoists depends on the hoistway

configuration and does not change in the course of operation. Hoisting equipment adapted to lift loads vertically is called a lift. Gaining ground in the industry on an ever-increasing scale, lifts are used in storehouse handling, at mines as auxiliary hoists for hauling men and supplies. They give their helping hand at construction sites, are indispensable in running multistoried buildings, TV towers, radio relay towers and meterological towers. In goods lifts marketed nowadays preference is given to push button controls arranged either inside the car or at any of the landings. The only operations to be taken care of by hand are those of closing the car doors and dispatching the car to the requisite floor, while the rest of the lifting sequence – selecting the direction of travel, changing over to a low speed in approaching the requested floor, stopping the car occurs automatically. In some installations, the doors close before the car is set into motion and open on arriving at the landing requested also automatically on depressing the dispatch button. What is self-leveling, i.e. bringing the lift to a stop so that its platform is level with the landing, is a feature of primary importance in normal lift operation. The self-leveling ability is influenced by the speed of travel and the load handled, other things being equal. Since lift with a 20-ton capacity are a commonplace, one can easily imagine the results of a loaded lift to fail to stop at the point it commonly stops when light. To avoid this, high-capacity lifts operate at low speeds. To ensure accurate self-leveling, lifts are equipped with creeping drives. In such a case, the depressisng of the dispatch button sets the main drive into operation, causing the car to go at a high speed. While approaching the landing requested, the main drive is automatically cut out and the creeping drive takes over, developing a horse-power which is only a fraction of that of the main drive. Consequently, the car is slowed down to a speed which is 1/10 to 1/20 of the previous one before being automatically stopped at the landing. Passenger lift installed in low-rise apartment houses range in capacity between 350 and 500 kg and operate at speeds between 0.65 and 1 m/s. Lifts serving 6 to 10 storied buildings have as a rule a speed of 0.65 m/s and those operating in taller buildings (up to 14 stories) run at 1 DOMHS

111 m/s, being consequently equipped with a two-speed drive. The cars of lifts installed in very tall buildings shuttle at speeds ranging between 1.5 to 3.5 m/s depending on the height. An increase in the effective handling capacity of lifts is achievable either by increasing their speed or by shortening the periods of starting and retarding. Yet, these periods cannot be shortened beyond a certain limit taking into account that rapid acceleration and sudden retardation are likely to cause passengers discomfort. This is the reason why modern lifts are rated to operate at accelerations and declarations not in excess of 1.5 m/s2. Lift operating at a speed of 1.5 m/s or less are equipped with geared motor drives, but high speed lifts have their traction-type driving sheave linked directly (without a reduction gearing) to the shaft of a low-speed D.C. motor. Unattended freight lift differ from passenger lifts and attended freight lifts by a simplified construction and a less number of safety gadgets. The speed of unattended freight lifts is between 0.1 and 0.3 m/s and that of attended ones, up to 1 m/s. The so-called ropeless lift, developed in recent years, is used to hoist men, tools, and supplies to the top of oil well derricks, very tall buildings, radio and TV towers. The car of a ropeless lift travels along guide rails due to traction between drive rollers and the flanges of guide rails. Alternatively, a drive of the rack-and-pinion type is used to set the car into motion. The passenger lift illustrated in Fig 23 essentially consists of a car 6 traveling over a set of rigid guide rails 5 which keep the car restrained laterally and provide support for it with the aid of special safety devices 10 should the hoisting rope 3 rupture. A hoisting machine 1 is arranged at the top or bottom of hoistway, with the top arrangement preferred in passenger installations.

To reduce the load on the hoisting machine, counterweight 7 is commonly

employed. Running along a separate set of guide rails 4 it offsets the car’s mass and half the duty load.

The safeties are adjusted to operate when the descending speed of the car becomes

excessive, a governor 2 operated from a separate rope 9 being provided in the machine room for the purpose of regulating the speed. Buffers 8 are arranged at the bottom of the hoistway, and lift control 11 (commonly magnetic switches) are found in a cubicle next to the hoisting machine.

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112

HOISTING MECHANISM

SAFETY BRAKES

ROPE(WIRE) CAR

COUNTER BALANCE WEIGHT

GUIDE RAIL FOR COUNTER WEIGHT

GUIDE RAILS FOR CAR

GROUND FLOOR

FIG NO.23 PASSENGER LIFT SKIP HOISTS :-

A device for lifting or lowering objects suspended from a hook at the end of returnable chains or cables, usually supported from overhead by a hook or traveling on a track. Hoisting equipment for the handling of bulk material in self-dumping or skips is called Buckets or skip hoists. They are used to charge blast furnaces, cupolas, etc. Skip hoists fall into three types differing by the way the skip is balanced. The type illustrated in Figure 24(a), is provided with a counterweight offsetting the mass of the empty skip plus half the duty load. The power requirement of this hoist are the same whether the skip is hoisted or lowered, amounting to what is needed to lift half the duty load. Skip hoists of this kind are employed in installations of medium and high lifting capacity and a medium effective handling capacity. Another typical arrangement of skip hoists is one with two skips moving in opposite direction (Figure 24 b). The winding machine provide only the force required to handle the duty load in just one of the skips. This equipment is used when high effective handling capacities are required and the height of lifts is also high.

DOMHS

113 The skip hoist of the third type is arranged to operate unbalanced (Figure 24 c), the load on the winding machine being in this case the equivalent of the mass of duty load plus that of skip. They are ideal in light and medium capacity installations operating from time to time at a moderate daily running.

FIG NO.23 SKIP HOIST AYOUT

Skips are all of the self-dumping type, being emptied either through a drop bottom or due to tilting. For tilting, which takes place when the skip arrives at the highest point of its path, the front and rear wheels are arranged to travel on different tracks so that when the front wheels engage a horizontal or slightly inclined length of track the rear wheel continue their upward travel with the result that the skip overturns, discharging its contents. CHARACTERISTICS :

1. Simple and inexpensive. 2. Easy installation. 3. Rugged and dependable. 4. Versatile. Operate by hand (chain), air, or electricity,

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114 USES :

1. Relatively light loads. 2. Intermittent moves. 3. Varying loads. 4. Serving a machine or work place. 5. High volume. 6. Long distances. 7. Varying routes. LIMITATIONS :

1. Must allow space for chain to clear corner. 2. Need smooth surface. FORK LIFT TRUCK (FIG 24) :COLUMN

DRIVER SEAT PALLET LOAD

FORK

FIG NO.24 FORK LIFT TRUCK

A self-loading counterbalanced, self-powered, wheeled vehicle, carrying a operator, and designed to carry a load on forks (or other attachment fastened to telescoping mast mounted ahead of the vehicle to permit lifting and stacking of loads). CHARACTERISTIC :

1. May be powered by gasoline, battery, or L.P. gas engine. 2. Mast may be tilted forward or backward to facilitate loading and unloading. 3. Operator may ride in center or at back end of truck- or with special attachments, on the lifting mechanism, with the load. DOMHS

115 4. Operator may sit or stand. 5. Use with a wide variety of attachments to provide an extremely flexible and adaptable handling device. 6. Carries own Power source therefore useful away from power lines. 7. Wheels and tires can be provided for a variety of floor conditions or operating locations – wood, concrete, highway, yard. 8. Wide range of capabilities. Electric type especially useful where reduced noise, or no fumes are desired. 9. USES :

1. Lifting, lowering, stacking, unstacking, loading, unloading, maneuvering. 2. Variable and flexible path. 3. Medium to large unit. 4. Uniform shaped loads. 5. Low to Medium volume of material. 6. Intermittent moves. LIMITATIONS :

1. Usually requires skid, pallet or container. 2. Gas-noisy, fumes, high maintenance. 3. Electric-slower, high initial cost, low maintenance. 4. Requires suitable running surface. 5. Requires adequate clearance. 6. Requires skilled operator. 7. Requires maintenance facility. 8. Power source tied to vehicle. 9. Usually uneconomical for moves over 300 ft. 10. Travel speed limited to 6-10 mph. 11. Lift speed limited to 80 fpm. 12. Grades limited. 13. Lift height up to 20 ft. 14. Load limited. 15. Relatively high deadweight to load capacity. DOMHS

116 16. Efficiency depends on operator. WINCHES (FIG 25) :-

Winches are another hoisting machinery, are used mainly for lifting loads but in some applications they are employed to haul them. CLASSIFICATION :

They are available in numerous arrangements and can be classed according to the following criterion, A. Means of traction employed a. Rope Winches and b. Chain Winches. B. Way of mounting a. Stationary Wiches 1. floor mounted 2. wall mounted 3. ceiling mounted b.

Mobile Winches

1. trolley or crab mounted 2.traveling over the floor or overhead track. C. Number of Drums a. Single Drum Winches. b. Twin Drum Winches. c. Multi-drum Winches. D. Type of Drum a. Grooved-drum Winches. b. Smooth-drum Winches. c. Whelped-drum Winches. The above Winches are widely used in various erection and repair jobs as well as in construction, Winches used in passenger lifts have traction type sheaves as shown in which the line pull is produced due to traction set up between the rope and sheave groove. To handle light loads at slow speeds, use is made if Hand Winches fitted with a hand crank and a brake to rotate the drum and to automatically stop the car when the crank is at rest. DOMHS

117 Material handling operations inside a shop and between shops are taken care of by compact hoisting Winches. These are also used for deliveries to in line production and automatic transfer lines, and to machine tools as well. REPAIRS AND MAINTENANCE OF MATERIAL HANDLING EQUIPMENT :-

The proper maintenance of material handling equipment’s is extremely essential for preventing the occurrence of bottlenecks or points of congestion’s. Production line flow can be maintained only if the material handling equipment is in the proper working order. Preventive maintenance is by far one of the best maintenance techniques suggested for material handling equipment. By Preventive Maintenance, the equipment can be kept running thereby minimizing costly interruptions in the production schedule. A little periodic inspection and minor adjustments may be enough to prevent equipment breakdown.

Preventive maintenance consist of frequent

inspection and examination of material handling equipment’s, with special attention to the components requiring it. The aim is to uncover conditions leading to breakdown or harmful depreciation. Preventive maintenance also includes lubrication, adjustment, or repair while the equipment is still in a minor stage of defect. Three stages of Preventive Maintenance are : 1. Inspection, 2. Repair, and 3. Overhaul. The Maintenance system for a few material Handling Equipment’s like Hoist, cranes, and Conveyors have been discussed below : A. HOISTS AND CRANES a.Inspection : All parts, open or covered are inspected for wear and tear. Worn out or unworkable

components like wire ropes, wheels, bearings, bolts, etc., are removed. Brakes are adjusted and lubrication is provided wherever necessary. b.Repair: The repairable parts of the system, after inspection are corrected for small repairs and

minor defects are rectified, Systems like open gear transmission, couplings, riverted, and bolted joints, trolley, brakes, guards, etc., may be repaired.

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118 c.Overhaul: Overhauling involves dismantling the complete mechanism and replacing all

damaged components. Crane structure, buffers, rails, open gear transmission, pulley blocks, etc., may be replaced and various sub-mechanisms may be aligned and adjusted. B. CONVEYORS: a. Inspection : Belts and roller are inspected for tensions and wear and tear. Gear box is

properly lubricated, various fasteners are tightened and safety guards are checked. b.Repairs : Rollers and Belt are checked, adjusted or repaired. Couplings, packing, safety

guards, steel structures, gear transmission, bearings, fastener joints, threaded components, etc., are adjusted or repaired as per their conditions. c. Overhaul : The conveyor system is completely dismantled. Components, worn out and

beyond repair like belts, bearings, packings, oil seals, rollers, drums, fasteners, and couplings are replaced. Structure, safety guards, etc., may be repaired as per their conditions. HAZARDS WITH MATERIAL HANDLING EQUIPMENT :-

There are accident causes by moving machinery or equipment in the materials handling function in industry. This section will discuss some of this causes. 1.Fork lift trucks accident are important not only in frequency but in severity among Industrial Accidents. Following are the 10 most common types of Fork lift truck accidents, a) Worker struck by Fork Lift Truck. b) Worker struck by object. c) Operator struck by falling object. d) Other worker struck by object. e) Mounting or dismounting Fork lift truck. f) Fork-lift truck overturns. g) Collision with other vehicle. h)Fork-lift Truck falling of the dock. i) Body part struck by object. j) Parts falling back on the operator. 1. Fork-lift operating on Gas are noisy and produces fumes which create Health Hazard. 2. The chief hazard from Conveyors is a worker coming in contact with the moving conveyor or its load. Accident may result from broken parts and component failure of conveyors. DOMHS

119 3. The potential for serious accidents from cranes and Hoists is high. Most involve running into workers or dropping loads which strike a worker. In ladle Crane, due to the failure of Auxilairy hoist, molten metal may falls on the operator resulting in serious accidents. Due to the failure of Limit Switches Excessive trolley travel and weight displacement may occur resulting in serious hazard. 4. The average person seldom thinks of a small container such as a tote box as a accident source. However, one can cause an accident. A common type is muscle or back strain through improperly lifting of a loaded tote box. Another type of accident is dropping a loaded tote box on a worker’s foot. 5. Tripping and falls are two common types of industrial accidents in American Industry. The failing of the load may occur due to excessive lubrication and faulty installations of the parts of the equipment. Although most accidents are minor, they can be serious, causing disability and even a fatality. 6. Inefficient Braking is one of the causes ofr the hazards in the Material Handling Equipment. Due to the inefficient braking, the Material required at a specified or desired location will not be available there. There will not be any control over the speed with which the Material is to be moved, e.g. If the load is of amorphous type it will flew away because of the excessive speed. If the Material is to be carried from higher location to the lower location, the speed must be controlled and for this reason only efficient braking is required. 7. In Pnuematic Conveyors, due to the choking of the Ducts or Nozzle, conveying becosdmes impossible. Also in Hydraulic Conveyors the leakage of pipeline may loose the pressure head. 8. Accidents may result in the passenger lift operated on rope due to the breakdown of the rope.

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120 REVIEW QUESTIONS :-

Q.No.1: Explain the working of ladle crane with its advantages ? Q.No.2: Discuss any two types of winches, with neat sketches? Q.No.3: What are different causes of accident? Q.No.4: Brief out preventive maintenance required for a screw conveyor, in general? Q.N0.5: Explain working of fork Lift truck with neat sketch? Mention it’s wide use in Industry? Q.No.6: How electric lift plays its roll in material handling systems? Q.No.7: What are the hazards associated with overhead material handling systems? Q.No.8: (a) Describe the operation flexibility of facts lift trucks ? (b) Compare passenger safety between escalators and passenger lift ? (c) What is winch ? Q.No.9: (a) How accidents associated with belt conveyor can be prevented ? (b) Explain the construction, working and application of ladle cranes ? Q.No.10: (a) Explain various hazards related with material handling equipments ? How they are eliminated ? (b) Describe the working principle and give advantage of following & application. (i) Ladle crane. (ii) Skip hoists. Q.No.11 : (a) Give general safety rules for material handling equipments ? (b) Describe how fork truck is versatile ? Q.No.12 : (a) Explain in details working of fork truck with neat sketches with characteristic uses and limitations ? (b) Explain in details repair and the maintainances of conveyor ? Q.No.13 : Explain the working of electric lift with neat sketch. State its application ? What is its limitation ? Q.No.14 : (a) Explain any two types of winches with neat sketches. State their uses ? (b) What are limitation of winches ? Q.No.15 : (a) Write a short note on ‘ ladle crane ? (b) Explain special features of fork lift truck . Give its application ? Q.No.16 : (a) How electric lift plays its role in material handling system ? (b) What are the different types of causes of accident ? Q.No.17: What are the types of repairs normally occure in automatic DOMHS

121 material handling equipment ? Q.No.18 : (a) Brief out preventive maintenance required for screw conveyor in general ? (b) What are the general safety rules adopted for material handling equipment during their installation and use ? Q.No.19 : (a) Describe principle of fork lift truck give its advantages and disadvantages ? (b) Describe the safety precaution adopted in case of belt conveyor ? Q.No.20 : (a) What are the various types of industrial trucks ? (b) What are different type of winches ? Explain its various application ? Q.No.21 : (a) Explain in details the procedure used for the maintenance of any one material handling equipments ? (b) Explain any one type of fork lift truck used in industry ?

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122 CHEMICAL TECHNOLOGY 1. Emerging role of the paint industry in improving human health 2. Role of software in Chemical Engg. 3. Xylitol Technology CIVIL ENGINEERING 1. Advanced composite materials an alternative to reinforcement, tendons and cables 2. Drainage problems related to irrigation in Maharashtra 3. Fly ash sand lime brick - an alternative walling material 4. Latex modified SFRC beam-column joints subjected to cyclic loading 5. Reinforced earthwork approach embankment using kologrid for rob at Murtijapur 6. Reinforcement detailing in non engineering and engineering earthquake resistant structures 7. Simplified CPM/PERT simulation model 8. Vaastu-shastra & its importance in residential building COMPUTER ENGINEERING 1. Groupware technology 2. Parallel processing in LINUX ELECTRICAL ENGINEERING 1. Application of superconductivity in electric power system 2. Cardiac pace-maker 3. Design of voltage regulator 4. Eco-friendly energy sources for rural development 5. Electric earthing and shock 6. Emission levels of a two-stroke S.I. Engine with in-cylinder fuel injection 7. Energy conservation in industry 8. Energy saving in home lighting 9. Future trends in technology for locomotive traction 10. HVDC transmission lines 11. Hydrostatic transmission for shunting locomotives 12. Internet & netsurfing 13. MHD-power generation 14. Mini Romag generator 15. Recycling of plastics 16. Selecting transformers for hydro power plants 17. Solar energetics in space 18. Substation ELECTRONICS ENGINEERING 1. Computer numerical control 2. Electronic multipoint fuel injection system 3. Fibre optical sources & detectors 4. Logic analyzer 5. Operation & temperature maintenance of Xerox Machine 6. Programmable logic controller 7. Radar system 8. Remote control system 9. Satellite tracking system

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123 10. Smartcard ASIC 11. Surface mount tech. 12. Wireless app protocol 13. Wireless network communication POLYMER TECHNOLOGY 1. Du pont fibre 2. Effect of electric field on structure property of polymers 3. Fluidized bed for catalytic polymerization 4. Manufacturing of PU foams 5. Polymers used in artificial joints 6. Reactive extrusion 7. Self healing plastic 8. Shoe sole manufacturing tech 9. Thermoplastic composites TEXTILE ENGINEERING 1. Application of it in textile 2. Bale management 3. Energy saving through spindle oil in ring frame 4. Fabric quality inspection 5. Furnishing & industrial application 6. The ABC of denim production PRODUCTION, MECHANICAL & AUTOMOBILE ENGINEERING 1. A solar chimney power plant 2. Air car 3. Air caster-a new approach in material handling 4. Aluminium space frame 5. Automated hydraulic control systems 6. Automatically guided vehicle system 7. Automobile air conditioning 8. Basic technology & drive system of industrial robots 9. Benchmarking 10. Buffering of serial production line 11. CADCAM-Revolutionising the aircraft industry 12. Caged ball technology 13. Catalytic converter in diesel engine 14. Components of missile 15. Computational fluid dynamics 16. Crash safety 17. Cryogenic treatments of different metals 18. Cybernetics in industry 19. D.M.D. Technique 20. Design innovation through digitalisation 21. Droplet welding 22. Electro-hydraulic proportional control valve 23. Emission levels of two stroke S.I. Engine

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124 24. Energy conservation in industries 25. ERP - An Indian case study 26. Experimental setup & assembling of car for lab. Development 27. Flying train 28. Flywheel spin in electric vehicle 29. Future trends in technology for locomotive traction 30. Green refrigeration 31. Helical gear manufacturing by extrusion 32. Holography 33. How to achieve fuel economy in automobile 34. How to run a small scale industry 35. Human factor in product design 36. Hybrid electric vehicle 37. Indian industry in a liberal market 38. Industrial corrosion & it’s prevention 39. Industrial research & development 40. Internal controls 41. Internet and netsurfing 42. Job analysis 43. Liquid-fuel rocket engine 44. LPG as alternative fuel for two wheelers 45. Machine vision system 46. Maintenance management 47. Motivation 48. Networking technologies 49. Occupant safety restraint devices in automobile 50. Physical facilities 51. Poka Yoke 52. Productivity improvement 53. Rapid prototyping 54. Recycling of plastic 55. Risk and forecasting 56. Robotization of forging industries 57. Round printing machine 58. Sensotronic brake control 59. Solar power vehicle 60. Sophisticated programmable industrial robotic arm 61. Statistical process control 62. Strategic about manufacturing 63. Study of pull boring machine 64. Supply chain management & its implementation by ethics value system 65. Technological options for future manufacturing 66. The global positioning system 67. Waterjet cutting PRINTED FORMAT 68. Re- Engineering A Potent Tool in Managing Change DOMHS

125 69. Challenges to industrial organisation & management 70. Pattern making 71. Vehicular pollution poisoning air in cities 72. Use of plastic as a tooling material 73. Use of robot in automobile manufacture 74. The engine of a sport car 75. Total productivity maintenance (TPM) 76. Screw Compressor bearing failure on process plant 77. Advanced control techniques for automobile exhaust pollution 78. On development of an electronically controlled copying lathe 79. Hydrostatic transmission for shunting locomotive 80. Environmental awareness and aluminium industry 81. Management information system 82. Cooling fans of air cooled DEUTZ diesel engines and their noise generation 83. Automotive emission control 84. Automation of injection moulding machine used hydraulic systems 85. Air oil cooling method for hard turning process 86. Packaging Technology 87. Investigation of factors affecting wear characteristics in rubber - metal sliding contact 88. Industrial psychology 89. Management of change and taskforce approach 90. Managerial effectiveness - key to productivity 91. New turns in thread cutting 92. Precision hole making by deep hole drilling method 93. Pricing Strategy - An introduction 94. Rotary ultrasonic machine 95. Ways towards the heavy duty diesel 96. Industrial problems solving through Japanese techniques 97. Robotisation of forging industry

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