Facility Layout: By H.s.pundle

Facility Layout By H.S.Pundle

Facility (Plant) Layout 

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Plant layout is disposition of various facilities within the site selected. Plant layout is placing the equipment in right place to permit processing of product in the most effective manner. Long term decision since change/ modification at considerable cost & disruption of production.

Objectives of Good Plant Layout 

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Economy in handling Material, WIP, Finished goods. Efficient utilization of available space. Easy supervision & better product control. Greater flexibility for product change & future expansion. Better working condition. Eliminate causes of excessive noise, smoke, odour.

Principles of Good Layout   

Minimum movement. Unidirectional flow without any backtracking. Effective use of available space: 

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Should be piled-up vertically with the help of pallets.

Maximum visibility. Maximum accessibility: 

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Sufficient clearance between m/cs & wall for maintenance. Area in front of fire extinguisher; electrical panels to be kept free.

Principles of Good Layout 

Minimum handling: 

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Inherent safety:  

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Aisles marked & kept free. Fire extinguishers kept at strategic location.

Improved Environment:  

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Material kept at working height on trolleys.

Free from odor, smoke etc. Smooth colours for walls.

Maximum Flexibility:  

For future expansion & flexibility. For Standardization.

Types of Layout – Product Layout Product A Lathe

Product B

Product C

Drilling

Milling

Gear Shaping

Grinding

Drilling

Deburring

Lathe

Deburring

HT

Milling

Grinding

Deburring

Assembly

Press Welding

Types of Layout – Product Layout 

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Suitable when products are standard & required in large quantity. Processing time of individual operation is more or less equal. Uninterrupted supply of material is must. Advantages:  

Reduced WIP. Material handling minimum & automatic.

Types of Layout – Product Layout 

Advantages (contd):  

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Production planning & control simple. Delivery commitments to customer are more reliable.

Disadvantages: 

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Change of product or technology difficult to accommodate. M/cs not used to full capacity; resulting in higher capital cost. Break down of one m/c, renders full line idle. Monotony of work.

Types of Layout – Process Layout Lathe section

Gear Shaping

Deburring

HT

Grinding

Drilling

Types of Layout – Process Layout  

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Associated with batch production. Suitable when products are nonstandard & wide variation in processing time of individual operation. Advantages: 

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Lower Capital investment on account of less number of m/cs. Higher utilization of equipment.

Types of Layout – Process Layout 

Advantages (contd): 

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Greater flexibility with regard to allocation work or equipment to worker. Break down of equipment; absence of workmen or non-availability of material does not dislocate the manufacturing activity. Workers attain higher skills. Imbalance of work in one section does not affect other section. Work interesting (not monotonous).

Types of Layout – Process Layout 

Disadvantages:   

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Higher WIP required. Routing & scheduling difficult. Inspection required to be done after each operation. Frequent set-up changes & associated costs.

Types of Layout – Cellular Layout 

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Also known as combination layout or Mixed layout. Similar type of operations for a group of products. Machines are grouped together into a cell. Utilize principles of single piece flow; multi m/c manning. Has enough flexibility. SMED is a must.

Types of Layout – Cellular Layout 

Advantages:   

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Reduced WIP. Improved quality. Reduced manpower.

Disadvantages: 

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Possible only when similar products can be grouped together. M/cs not used to full capacity; resulting in higher capital cost.

Assembly Lines  

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A special case of product layout. In general term refers to progressive assy linked by some material handling device (Conveyor or crane). Some form of pacing is present & allowable processing time is equivalent for all workstations. Workers may sit, stand, walk with the line. Virtually any product that has multiple parts & is produced in large volume uses assy line.

Assembly line Balancing 

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A moving conveyor that passes a series of workstations in a uniform time interval called the workstation cycle time. At each workstation, work is performed on a product either by adding parts or by completing assy operation. Work performed is made up of many tasks, elements & work units.

Assembly line Balancing 

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Total work to be performed at a workstation is equal to the sum of tasks assigned to that workstation. Assy line balancing problem is one of assigning tasks to the workstation so that a) Tasks can be completed in workstation cycle time & b) Idle time (Unassigned time) is minimized. The problem is complicated by precedence relationship which specifies the sequence in which tasks must be performed.

Steps in Assy Line Balancing 

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1. Specify the sequential relationship using precedence diagram. 2. Determine workstation cycle time. Cycle time C = Production Time per day Required output per day

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Determine theoretical minimum no. of workstations N = Sum of task time T Cycle time C

Steps in Assy Line Balancing 

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4. Select primary rule by which tasks are to be assigned & secondary tie breaker rule. 5. Assign tasks to the 1st workstation until a) sum of task time equals cycle time or b) No other tasks are feasible because of sequence restrictions. Repeat the process for workstation 2 , 3 & so on. 6. Evaluate the line efficiency using formula Efficiency =

Sum of task time Actual No. of workstations X Cycle time

7. If efficiency is low; rebalance using different decision rule (step 4 onward).

Assembly Lines Balancing Concepts Question: Question:Suppose Supposeyou youload loadwork workinto intothe thethree threework work stations stationsbelow belowsuch suchthat thateach eachwill willtake takethe thecorresponding corresponding number numberof ofminutes minutesas asshown. shown. What Whatis isthe thecycle cycletime timeof of this thisline? line?

Station 1

Station 2

Station 3

Minutes 6 7 3 per Unit Answer: Answer:The Thecycle cycletime timeof ofthe the line lineis is always always determined determinedby bythe thework workstation stationtaking takingthe thelongest longest time. time. In Inthis thisproblem, problem, the thecycle cycletime time of of the theline lineis is77 minutes. minutes. There Thereis isalso alsogoing goingto tobe beidle idletime timeat atthe the other othertwo twowork workstations. stations.

Example of Line Balancing 

You’ve just been assigned the job a setting up an electric fan assembly line with the following tasks:

Task A B C D E F G H

Time (Mins) 2 1 3.25 1.2 0.5 1 1 1.4

Description Assemble frame Mount switch Assemble motor housing Mount motor housing in frame Attach blade Assemble and attach safety grill Attach cord Test

Predecessors None A None A, C D E B F, G

Example of Line Balancing: Structuring the Precedence Diagram Task Predecessors A None B A C None D A, C A

Task Predecessors E D F E G B H E, G B

G H

C

D

E

F

Example of Line Balancing: Precedence Diagram Question: Question: Which Which process process step step defines defines the the maximum maximum rate rate of of production? production?

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

1.4 H

Answer: Answer: Task TaskCCis isthe thecycle cycletime timeof of the theline lineand and therefore, therefore, the themaximum maximumrate rateof ofproduction. production.

Example of Line Balancing:

Cycle Time

Determine

Question: Question: Suppose Suppose we we want want to to assemble assemble 100 100 fans fans per per day. day. What What would would our our cycle cycle time Answer: time have have to to be? be? Answer: Production time per period Production time per period Required RequiredCycle CycleTime, Time, CC== Required output per period Required output per period

420 mins //day 420 mins day = 4.2 mins / unit CC== = 4.2 mins / unit 100 units / day 100 units / day

Example of Line Balancing: Determine Theoretical Minimum Number of Workstations Question: Question: What What is is the the theoretical theoretical minimum minimum number number of of workstations workstations for for this this problem? problem?

Answer: Answer:

Theoretical TheoreticalMin. Min. Number Numberof ofWorkstations, Workstations, NNt t Sum of task times (T) Sum of task times (T) NNt == t Cycle Cycletime time(C) (C)

11.35 mins //unit 11.35 mins unit = 2.702, or 3 NNt == = 2.702, or 3 t 4.2 mins / unit 4.2 mins / unit

Example of Line Balancing: Rules To Follow for Loading Workstations 

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Assign tasks to station 1, then 2, etc. in sequence. Keep assigning to a workstation ensuring that precedence is maintained and total work is less than or equal to the cycle time. Use the following rules to select tasks for assignment. Primary: Assign tasks in order of the largest number of following tasks Secondary (tie-breaking): Assign tasks in order of the longest operating time

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1

1.4 H

Task A C D B E F G H

Station 2

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1 A (4.2-2=2.2)

1.4 H

Task A C D B E F G H

Station 2

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1 A (4.2-2=2.2) B (2.2-1=1.2)

1.4 H

Task A C D B E F G H

Station 2

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2

1.4 H

Task A C D B E F G H

Station 2

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2

1.4 H

Task A C D B E F G H

Station 2 C (4.2-3.25)=.95

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1

1.4 H

Task A C D B E F G H

Station 2

A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2)

C (4.2-3.25)=.95

Idle= .2

Idle = .95

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1

1.4 H

Task A C D B E F G H

Station 2

A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2)

C (4.2-3.25)=.95

Idle= .2

Idle = .95

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3 D (4.2-1.2)=3

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1

1.4 H

Task A C D B E F G H

Station 2

A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2)

C (4.2-3.25)=.95

Idle= .2

Idle = .95

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3 D (4.2-1.2)=3 E (3-.5)=2.5

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1

1.4 H

Task A C D B E F G H

Station 2

A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2)

C (4.2-3.25)=.95

Idle= .2

Idle = .95

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3 D (4.2-1.2)=3 E (3-.5)=2.5 F (2.5-1)=1.5

2 A

1 B

1 G

C

D

E

F

3.25

1.2

.5

1

Station 1

1.4 H

Task A C D B E F G H

Station 2

A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2)

C (4.2-3.25)=.95

Idle= .2

Idle = .95

Followers 6 4 3 2 2 1 1 0

Time (Mins) 2 3.25 1.2 1 0.5 1 1 1.4

Station 3 D (4.2-1.2)=3 E (3-.5)=2.5 F (2.5-1)=1.5 H (1.5-1.4)=.1 Idle = .1

Which station is the bottleneck? What is the effective cycle time?

Example of Line Balancing: Determine the Efficiency of the Assembly Line Sum of task times (T) Sum of task times (T) Efficiency = Efficiency = Actual number of workstations (Na) x Cycle time (C) Actual number of workstations (Na) x Cycle time (C)

11.35 11.35 mins mins // unit unit Efficiency =.901 Efficiency == =.901 (3)(4.2mins (3)(4.2mins // unit) unit)

Designing and Developing New Services Three general dimensions of service design are: 

Degree of Standardization of the Service

Custom-fashioned for particular customers or basically the same for all customers? Degree of Customer Contact in Delivering the Service  High level of contact (dress boutique) or low level (fast-food restaurant)?  Mix of Physical Goods and Intangible Services  Mix dominated by physical goods (tailor’s shop) or by intangible services (university)? 

Designing and Developing New Services 

Differences Between New Service and New Product Development 

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Unless services are dominated by physical goods, their development usually does not require engineering, testing, and prototype building. Because many service businesses involve intangible services, market sensing tends to be more by surveys rather than by market tests and demonstrations.

Major Factors Affecting Process Designs     

Nature of product/service demand Degree of vertical integration Production flexibility Degree of automation Product/Service quality

Nature of Product/Service Demand 

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Production processes must have adequate capacity to produce the volume of the products/services that customers need. Provisions must be made for expanding or contracting capacity to keep pace with demand patterns. Some types of processes are more easily expanded and contracted than others. Product/service price affects demand, so pricing decisions and the choice of processes must be synchronized.

Degree of Vertical Integration 

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Vertical integration is the amount of the production and distribution chain that is brought under the ownership of a company. This determines how many production processes need to be planned and designed. Decision of integration is based on cost, availability of capital, quality, technological capability, and more. Strategic outsourcing (lower degree of integration) is the outsourcing of processes in order to react quicker to changes in customer needs, competitor actions, and technology.

Production Flexibility 

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Product flexibility -- ability of the production (or delivery) system to quickly change from producing (delivering) one product (or service) to another. Volume flexibility -- ability to quickly increase or reduce the volume of product( or service) produced (or delivered).

Degree of Automation 

Advantages of automation   

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Improves product quality Improves product flexibility Reduces labor and related costs

Disadvantages of automation  

Equipment can be very expensive Integration into existing operations can be difficult

Product/Service Quality 

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Old viewpoint – high-quality products must be made in small quantities by expert craftsmen New viewpoint – high-quality products can be mass-produced using automated machinery Automated machinery can produce products of incredible uniformity The choice of design of production processes is affected by the need for superior quality.

Types of Process Designs   

Product-Focused Process-Focused Group Technology/Cellular Manufacturing

Product-Focused 

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Processes (conversions) are arranged based on the sequence of operations required to produce a product or provide a service Also called “Production Line” or “Assembly Line” Two general forms  

Discrete unit – automobiles, dishwashers Process (Continuous) – petrochemicals, paper

Product-Focused Components 22

1

Raw Material

4

Co m po n.

Su ba ss em .

3

Components

1 Product/Material Flow

Production Operation

Assemblies

5

7

Subassem. Purchased 6

Components, Subassemblies

Fin. Goods

s se m bl ie s A

Raw Material

Product-Focused 

Advantages    

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Lower labor-skill requirements Reduced worker training Reduced supervision Ease of planning and controlling production

Disadvantages  

Higher initial investment level Relatively low product flexibility

Process-Focused 

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Processes (conversions) are arranged based on the type of process, i.e., similar processes are grouped together Products/services (jobs) move from department (process group) to department based on that particular job’s processing requirements Also called “Job Shop” or “Intermittent Production” Examples  

Auto body repair Custom woodworking shop

Process-Focused Custom Woodworking Shop

Custom Woodworking Shop

Cutting Planing Shaping Assembly Sanding Finishing 1 Job A A Job B 1

22

55

66

55

66

33

22

44

33 44

Drilling Turning

7

Process-Focused 

Advantages  

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High product flexibility Lower initial investment level

Disadvantages    

Higher labor-skill requirements More worker training More supervision More complex production planning and controlling

Group Technology/Cellular Manufacturing 

Group Technology 

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Each part produced receives a multi-digit code that describes the physical characteristics of the part. Parts with similar characteristics are grouped into part families Parts in a part family are typically made on the same machines with similar tooling

Group Technology/Cellular Manufacturing 

Cellular Manufacturing 

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Some part families (those requiring significant batch sizes) can be assigned to manufacturing cells. The organization of the shop floor into cells is referred to as cellular manufacturing. Flow of parts within cells tend to be more like product-focused systems

Group Technology/Cellular Manufacturing 

Advantages (relative to a job shop)  

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Process changeovers simplified Variability of tasks reduced (less training needed) More direct routes through the system Quality control is improved Production planning and control simpler Automation simpler

Group Technology/Cellular Manufacturing 

Disadvantages   

Duplication of equipment Under-utilization of facilities Processing of items that do not fit into a family may be inefficient

Process Design in Services 

Some of the factors important in process design for products are also important in services:     

Nature (level and pattern) of customer demand Degree of vertical integration Production flexibility Degree of automation Service quality

Process Design in Services 

Three schemes for producing and delivering services   

Quasi-Manufacturing Customer-as-Participant Customer-as-Product

Process Design in Services 

Quasi-Manufacturing 

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Physical goods are dominant over intangible service Production of goods takes place along a production line Operations can be highly automated Almost no customer interaction Little regard for customer relations Example – bank’s checking encoding operation

Process Design in Services 

Customer-as-Participant 

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Physical goods may be a significant part of the service Services may be either standardized or custom High degree of customer involvement in the process Examples: ATM, self-service gas station

Process Design in Services 

Customer-as-Product 

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Service is provided through personal attention to the customer Customized service on the customer High degree of customer contact There is a perception of high quality Customer becomes the central focus of the process design Examples: medical clinic, hair salon

Process Reengineering 

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The concept of drastically changing an existing process design Not merely making marginal improvements to athe process A correctly reengineered process should be more efficient A smaller labor force is often the result

Deciding Among Processing Alternatives   

Batch Size and Product/Service Variety Capital Requirements Economic Analysis   

Cost Functions of Alternative Processes Break-Even Analysis Financial Analysis

Large

Focused, Dedicated Systems Product Focused, Batch System Cellular Manufacturing Process-Focused, Job Shop

Small

Batch Size

Process Design Depends on Product Diversity and Batch Size Product

Few

Number of Product Designs

Many

Capital Requirements 

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The amount of capital required tends to differ for each type of production process Generally, the capital required is greatest for productfocused, dedicated systems Generally, the capital required is lowest for processfocused, job shops The amount of capital available and the cost of capital are important considerations

Economic Analysis 

Cost Functions of Processing Alternatives 

Fixed Costs  

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Annual cost when production volume is zero Initial cost of buildings, equipment, and other fixed assets

Variable Costs  

Costs that vary with production volumes Labor, material, and variable overhead

Cost Functions of Processing Alternatives Annual Cost of Production ($000) op h S b o J

2,000

in e L y l b m e s s Au t o m . A

1,500 1,000 500

Job Shop Preferred 100,000

Cellular Manufacturing Preferred

f. u n a M r a lul l e C

Automated Assembly Line Preferred Units Produced Per Year 250,000

Material Handling 

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Material Handling does not add to VALUE; it adds to COST. A good plant layout reduces material handling. Objectives of material handling:     

Minimization of cost of material handling. Prevention of damage to material. Safety of people involved. Good housekeeping. Minimization of fatigue.

Material Handling 

Purpose:       

Unloading of goods. Movement to stores. Movement to place of use. Movement within the shop. Movement of finished goods to packing. Finished goods storage. Dispatch.

Types of Material Handling Equipment    

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Wheel barrow. Platform trolley/Special purpose trolley. Pigmy trolley. Belt conveyor/Roller conveyor/screw conveyor. Forklift truck. Jib crane/Gantry crane/ EOT crane. Slides & Chutes.