Total Productivity And Quality Management
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Total Productivity and Quality Management
Natraj Korgaonkar S.Y.B.M.S. (A) - 46
Total Productivity and Quality Management
Otis Elevators
Elevator Industry with Special Emphasis on “Otis”
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Our Company OTIS-World's Largest... Otis is the world’s largest manufacturer of elevators, escalators, moving walks and other horizontal transportation systems. For architects and contractors, developers and homeowners, Otis is the world’s leading people mover. While we manufacture, install, modernize and maintain elevators, escalators, moving walks and shuttles, the heart of our business is problem solving. Whether a customer needs a sophisticated elevator system for the tallest building in the world or a simple lift for a two-story home, we are dedicated to providing the safest, most reliable solutions possible. Changing the shape of the world In 1853, Elisha Graves Otis introduced the world’s first safety elevator in Yonkers, New York —changing the shape of the modern world. From that point forward, buildings could rise beyond the limitations of stairs. Cities would have skylines. Today, our pioneering spirit is as strong as it was when we began. With every new product and service, Otis is moving our industry, our company and our customers forward. Sharing strengths Otis is part of United Technologies Corporation, a Fortune 500 company and world leader in the building systems and aerospace industries. Sharing strengths with UTC allows Otis to draw on remarkable resources in engineering, product testing, purchasing, marketing and information systems. Otis brings all these strengths to bear in creating better solutions for our customers.
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Safety first… The vertical transportation of people and materials to otherwise unobtainable heights was extremely hazardous until Elisha Graves Otis invented the “Elevator safety” in 1852. For ages, man had struggled with various means to transport heavy loads to higher places. By today’s standards, all were unsafe and most unsuccessful. Otis’ safety consisted of a wagon spring and a rack with teeth (ratchet) on the guide rails. If the hoist rope broke, the tension was released from the wagon spring allowing it to engage the ratchet and bring the car to a stop. The pioneering work of Elisha Graves Otis was carried by his sons, Charles and Norton. Many refinement have followed, but the concept is still “Safety First”.
Mr.Elisha Graves Otis displaying the first elevator.
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Products: Otis has mastered itself in the field of elevators since 1852. Ever since Mr. Otis introduced the first elevator to the world, there has been development carried through ages. Otis Elevator has now three main categories of products with different models in each section. They are as follows: Traction Elevators Hydraulic Elevators Escalators Each of these sections has around 200 models varying upon the capacity, the type of load being carried in the elevator, the height of the building, the speed required by customer and so. Again each of these categories has two main sub-groups: Passenger Elevators Cargo/ goods Elevators.
The elevator from outside.
The Escalator.
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Production Process The design and production of any of the elevators is done in Taiwan and in Korea. Unfortunately there is no Elevator company in India which has a production plant or factory in the country. All the companies along with Otis have their design and production plants outside the country. They only assemble and re-engineer the product at the site where the elevator has to be erected. This helps in saving a lot of technological cost because the company fins the technology cheap in the foreign markets. And thus only importing the required parts becomes cheaper in India that producing elevators. All the parts of the elevator or escalators are imported stored in the country. Otis Elevators has its own stores department and an official head office in Mumbai at Nepensea Road and Kandivli respectively. Thus as per the requirements of the workers working at various sites of the company the required goods or spare parts or the equipments are delivered to the site of erection or maintenance or both. Currently the company undertakes jobs or erection of elevators and escalators at various new places and maintenance of erected elevators. At times this may also include elevators produced by different companied for which Otis charges fee plus compensation.
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Process of Erection of Elevators with Time and Work Measurement: As said earlier the company does not indulge itself in the production of elevators in India and thus it imports all its requirements from its parent company across the globe, the company has a low cost advantage. Thus the company only takes orders from their clients and then order for the same and then erects the elevator or escalators at the site given to them. Following is the synopsis of the erection process of elevators: • Order: The order of the product is the first main stage of the erection of an elevator. As per the clients’ requirements for the type of elevator, size composition, cost analysis maintenance etc, the company advices the clients for any change if required in the order. The time taken for this process depends upon the negotiations and the company and the clients’ relationship. •
Company’s requirements: As per the clients’ requirements the company places its requirement of the hall way that would be required where the elevator would be place, the place and the area of the machine room, the pit- its depth, area, electricity connections, scaff-holding, shafts, etc. The time taken to complete all the company’s requirements would be the time taken by the builder to complete the main structure of the building. This would again depend upon the height of the building. •
Actual erection process: After the clients have given the company’s basic requirements that are necessary for erecting an elevator the actual process of erection begins. This starts with building the scaff-holdings (bamboo building structure) inside the hall way where one places the elevator and setting-up the machine room with the machine motor, brake assembly, controller, governor and then the work to construct the shaft begins. •
Combined work forces: By the time the machine room is set, other group of workers start setting up the hall buttons, landing doors on each floor, fixtures and assembling the pit just below the ground floor. The setting-up of the pit is the most important factor. This is the one which allows the car-lift to rest and prevent it from going further underground. In other words, it prevents free-fall of the car-lift by the use of counter buffer and oilbuffers. The time taken for the same process is same as the above as both the works is done at the same time.
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•
Assembling of the main car-lift: This the next stage in the erection of the car-lift in the hall-way. This is done by first setting-up the guide rails which are about 16m each in height. These are done upto the ceiling roof. Then the car-lift is set-up at the top floor with the counterweight on the ground floor. This is the main principle stage for the working of the elevator. If there is even a single mistake in determining the counterweight or assembling it right, the then whole elevator will crash within a second. If there is a perfect balance then the steel ropes are attached to the car-lift and the counterweight through the machine motor situated on the terrace just over the hall-way. Since this is the most crucial stage, takes around 8-10 days (for 6 storeyed building) depending upon the height of the building. •
Fixtures and buttons: After setting-up the main frame of he elevator, the next stage is setting up the fixture, buttons in the car-lift, coordinating open and close doors at each and every floor, testing each floor for reciprocal call etc. Sine this is minute but energy consuming process takes at least 6-8 days for a normal 6 storeyed building
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Management by Objectives Definition: -‘Management by Objectives’ is a comprehensive managerial system that integrates many key managerial activities in a systematic manner and that is consciously directed towards the effective and efficient achievement of organizational and individual objectives.
Evolving Concepts in MBO: • Early Impetus to MBO: Since many centuries people have used their common sense and given importance to management by objectives. It was in 1954 that Peter. F. Drucker first emphasized that objectives must be set in all areas where performance affects the health of the enterprise. About at the same time General Electric Co. was using MBO in its reorganization • Emphasis On Performance Appraisal: In traditional appraisal programs personality traits were used for evaluating subordinates. But when MBO was implemented emphasis was given on performance rather than personality which lead to self appraisal and self development. The active involvement of subordinates leads to commitment and creates an environment for motivation.
Emphasis on short-term objectives and motivation: Individual goal setting is an important factor in motivating employees. It is known that performance is higher when people have specific objectives than when they are asked simply to do their best.
• Inclusion Of Long Range Plan In MBO:
In MBO programs that emphasis performance appraisals and motivation the focus tends to be on short term objectives, which may lead to undesirable managerial behaviour. Due to these short-comings many organization now include long range and strategic planning in MBO programs. •
The System Approach To MBO MBO has undergone many changes. It has been used in performance appraisals as an instrument for motivating individual and in strategic planning. But there are still other managerial subsystems that can be integrated into MBO process. Various managerial activities need to be integrated into a system. For MBO to be a comprehensive system of managing indicates that most key managerial activities can and should be integrated with the MBO process. The degree of integration however differs for individual activities. For MBO to be effective it has to be viewed as a comprehensive system and it must be considered as a way of managing and not an addiction to the managerial job.
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The Process of Managing By Objectives: The process starts at the top of an organization and has the active support of the chief executive, who gives direction to the organization. It is not essential the objective setting starts at the top. It can start at the divisional level, at the marketing level or even lower level. As in all planning, one of the critical need in MBO is the development and dissemination of consistent planning premises. No manager can be expected to set goals or establish plans and budgets without guidelines.
Setting preliminary objectives at the top: Given appropriate planning premises, the first step in setting objectives is for the top manager to determine what he or she perceives to be the purpose or mission and the more important goals of the enterprise for a given period ahead. Certain goals should be scheduled for accomplishment in a much shorter period and others in a much longer period. The goals set by the superior are preliminary based on an analysis and judgment as to what can and should be accomplished by the organization within a certain period. This requires taking into account the company’s strength and weakness in the light of available opportunities and threats. Most managers also find out the process of working out goals with the subordinates reveals both problems they should deal with and the opportunities they were not previously aware of. When setting objectives, the manager also establishes measure of goal accomplishment. If verifiable objectives are developed, these measures, whether in sale dollars profits, percentages, cost level, or program execution, will normally built into objectives.
Clarifying Organizational Roles: The relationship between expected results and the responsibility of attaining is often overlooked. Ideally, each goal and sub goal should be one particular person’s responsibility. Analyzing an organization structure, however, often reveals that the responsibility is vague and the clarification or reorganization is needed. Sometimes it is impossible to structure an organization so that a given objective is someone’s personal responsibility.
Setting Subordinates Objectives: After making sure that subordinate managers have been informed of pertinent general objectives, strategies, and planning premises, the superior can then proceed to work with subordinates in setting their objectives. The superiors ask what goals the subordinates believe they can accomplish, in what time period and with what resources. Superiors must also be patient counsellors, helping their subordinates develop consistent and supportive objectives and being careful not to set goals that are impossible to
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achieve. One of the things that can weaken a program by objectives is to allow managers to set unrealistic objectives. One of the major advantages of carefully setting up a network of verifiable goals and a requirement for doing so effectively is trying in the need of capital, materials and human resources at the same time. All managers at all levels require these resources to accomplish their goals. By relating these resources to the goals themselves, superiors can better see the most effective and the most economical way of allocating them
Recycling of objectives: Objectives can hardly be set by starting at the top and dividing them up among subordinates nor should they be started from the bottom. A degree of recycling is a must. Top managers may have some idea of what their subordinates’ objectives should be; but they will almost certainly change these preconceived goals as the contributions of the subordinates come into focus. Thus setting objectives is not a joint process but also an interactive one.
Benefits of Management by Objectives: 1. Improvement of managing: Managing Sense in a Manager Improves. 2. Clarification of organization: Management by objectives forces managers to clarify roles i.e. organizational roles and structures. 3. Encouragement of Personal Commitment: It encourages people to commit themselves to their goals. 4. Development of Effective Controls: MBO helps in effective planning, it also aids in developing effective controls.
Weakness of Management by Objectives: 1. 2. 3. 4. 5.
Failure to teach the philosophy of MBO. Failure to give guidelines to goal setters. Difficulty of setting goals. MBO programs are set for short terms. Danger of inflexibility.
Total Quality Management 11
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Total Quality Management or TQM is a management strategy to embed awareness of quality in all organizational processes. Quality assurance through statistical methods is a key component. TQM aims to do things right the first time, rather than need to fix problems after they emerge or fester. TQM may operate within quality circles, which encourage the meeting of minds of the workforce in different departments in order to improve production and reduce wastage. In a Otis, TQM generally starts by sampling a random selection of the product. The sample is then tested for things that matter to the real customers. The causes of any failures are isolated, secondary measures of the production process are designed, and then the causes of the failure are corrected. The statistical distributions of important measurements are tracked. When parts' measures drift out of the error band, the process is fixed. The error band is usually tighter than the failure band. The production process is thereby fixed before failing parts can be produced. It's important to record not just the measurement ranges, but what failures caused them to be chosen. In that way, cheaper fixes can be substituted later, (say, when the produce is redesigned), with no loss of quality. After TQM has been in use, it's very common for parts to be redesigned so that critical measurements either cease to exist, or become much wider. It took people a while to develop tests to find emergent problems. One popular test is a "life test" in which the sample product is operated until a part fails. Another popular test is called "shake and bake". The product is mounted on a vibrator in an environmental oven, and operated at progressively more extreme vibration and temperatures until something fails. The failure is then isolated and engineers design an improvement. A commonly-discovered failure is for the product to come apart. If fasteners fail, the improvements might be to use measured-tension nutdrivers to ensure that screws don't come off, or improved adhesives to ensure that parts remain glued. If a gearbox wears out first, a typical engineering design improvement might be to substitute a brushless stepper motor for a DC motor with a gearbox. The improvement is that a stepper motor has no brushes or gears to wear out, so it lasts ten times or more longer. The stepper motor is more expensive than a DC motor, but cheaper than a DC motor combined with a gearbox. The electronics is radically different, but equally expensive. One disadvantage might be that a stepper motor can hum or whine, and usually needs noise-isolating mounts. Often a TQMed product is cheaper to produce (because there's no need to repair dead-onarrival products), and can yield an immensely more desirable product. TQM can be applied to services (such as mortgage issue or insurance underwriting), or even normal business paperwork. TQM is not a focused improvement approach. The customer desires and product tests select what to fix. Theoretical constraints are not considered at all.
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Scatter Diagrams This tutorial is designed to allow the user to develop and interpret scatter diagrams. When the scatter diagram has been plotted from the data, the user can view several different graphs within the Interpretations, read the interpretation of the diagrams pattern, and be able to draw conclusions about the plotted diagram by comparing it to one of the five possible graph patterns.
Overview Scatter diagrams are used to study possible relationships between two variables. Although these diagrams cannot prove that one variable causes the other, they do indicate the existence of a relationship, as well as the strength of that relationship. A scatter diagram is composed of a horizontal axis containing the measured values of one variable and a vertical axis representing the measurements of the other variable. The purpose of the scatter diagram is to display what happens to one variable when another variable is changed. The diagram is used to test a theory that the two variables are related. The type of relationship that exits is indicated by the slope of the diagram.
Key Terms
Variable - a quality characteristic that can be measured and expressed as a number on some continuous scale of measurement. Relationship - Relationships between variables exist when one variable depends on the other and changing one variable will affect the other. Data Sheet - contains the measurements that were collected for plotting the diagram. Correlation - an analysis method used to decide whether there is a statistically significant relationship between two variables. Regression - an analysis method used to identify the exact nature of the relationship between two variables.
Construction of Scatter Diagrams
Collect and construct a data sheet of 50 to 100 paired samples of data that you suspect to be related. Construct your data sheet as follows: Car (elevator) 1 2 3 4 : : : : 100
Age (In Years) 2 4 1 5 : : : : 7
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Price (In Dollars) 4000 2500 5000 1250 : : : : 1000
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Draw the axes of the diagram. The first variable (the independent variable) is usually located on the horizontal axis and its values should increase as you move to the right. The vertical axis usually contains the second variable (the dependent variable) and its values should increase as you move up the axis. Plot the data on the diagram. The resulting scatter diagram may look as follows:
Interpret the diagram. See interpretation section of tutorial.
Interpretations The scatter diagram is a useful tool for identifying a potential relationship between two variables. The shape of the scatter diagram presents valuable information about the graph. It shows the type of relationship which may be occurring between the two variables. There are several different patterns (meanings) that scatter diagrams can have. The following describe five of the most common scenarios: 1. The first pattern is positive correlation, that is, as the amount of variable x increases, the variable y also increases. It is tempting to think this is a cause/effect relationship. This is an incorrect thinking pattern, because correlation does not necessarily mean causality. This simple relationship could be caused by something totally different. For instance, the two variables could be related to a third, such as curing time or stamping temperature. Theoretically, if x is controlled, we have a chance of controlling y.
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2. Secondly, we have possible positive correlation, that is, if x increases, y will increase somewhat, but y seems to be caused by something other than x. Designed experiments must be utilized to verify causality.
3. We also have the no correlation category. The diagram is so random that there is no apparent correlation between the two variables.
4. There is also possible negative correlation, that is, an increase in x will cause a tendency for a decrease in y, but y seems to have causes other than x.
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5. Finally, we have the negative correlation category. An increase in x will cause a decrease in y. Therefore, if y is controlled, we have a good chance of controlling x.
Key Observations *A strong relationship between the two variables is observed when most of the points fall along an imaginary straight line with either a positive or negative slope. *No relationship between the two variables is observed when the points are randomly scattered about the graph.
RUN CHARTS/TIME PLOT/TREND CHART
PURPOSE In-depth view into Run Charts--a quality improvement technique; how Run charts are used to monitor processes; how using Run charts can lead to improved process quality
USAGE Run charts are used to analyze processes according to time or order. Run charts are useful in discovering patterns that occur over time.
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KEY TERMS Trends: Trends are patterns or shifts according to time. An upward trend, for instance, would contain a section of data points that increased as time passed.
Population: A population is the entire data set of the process. If a process produces one thousand parts a day, the population would be the one thousand items.
Sample: A sample is a subgroup or small portion of the population that is examined when the entire population can not be evaluated. For instance, if the process does produce one thousand items a day, the sample size could be perhaps three hundred.
INSTRUCTIONS FOR CREATING A CHART Step 1: Gathering Data To begin any run chart, some type of process or operation must be available to take measurements for analysis. Measurements must be taken over a period of time. The data must be collected in a chronological or sequential form. You may start at any point and end at any point. For best results, at least 25 or more samples must be taken in order to get an accurate run chart.
Step 2: Organizing Data Once the data has been placed in chronological or sequential form, it must be divided into two sets of values x and y. The values for x represent time and the values for y represent the measurements taken from the manufacturing process or operation.
Step 3: Charting Data Plot the y values versus the x values by hand or by computer, using an appropriate scale that will make the points on the graph visible. Next, draw vertical lines for the x values to separate time intervals such as weeks. Draw horizontal lines to show where trends in the process or operation occur or will occur.
Step 4: Interpreting Data After drawing the horizontal and vertical lines to segment data, interpret the data and draw any conclusions that will be beneficial to the process or operation. Some possible outcomes are: • Trends in the chart • Cyclical patterns in the data • Observations from each time interval are consistent
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RUN CHART EXAMPLE Problem Scenario We use the run chart for data analysis of workers time-in and time-out. This is illustrated in the given data where we have shown the days and time taken by a worker to reach his office.
Step 1: Gathering Data Collect measurements each day over the next four weeks. Organize and record the data in chronological or sequential form. M WEEK WEEK WEEK WEEK
1 2 3 4
33 35 34.5 34
T 28 30.5 29 29.5
W
TH
26.5 28 28 27
28 26 26 27
F 26 25.5 25 25.5
Step 2: Organizing Data Determine what the values for the x (time, day of week) and day (data, minutes to work) axis will be.
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Step 3: Charting Data Plot the y values versus the x values by hand or by computer using the appropriate scale. Draw horizontal or vertical lines on the graph where trends or inconsistencies occur.
Step 4: Interpreting Data Interpret results and draw any conclusions that are important. An overall decreasing trend occurs each week with Mondays taking the most amounts of time and Fridays generally taking the least amount of time. Therefore you accordingly allow yourself more time on Mondays to arrive to work on time.
Histograms The histogram will provide information on quality process control (Q.C.). The histogram evolved to meet the need for evaluating data that occurs at a certain frequency. This is possible because the histogram allows for a concise portrayal of information in a bar graph format. The histogram is a powerful engineering tool when routinely and intelligently used. The histogram clearly portrays information on location, spread, and shape that enables the user to perceive subtleties regarding the functioning of the physical process that is generating the data. It can also help suggest both the nature of, and possible improvements for, the physical mechanisms at work in the process.
Purpose: The purpose is to become familiar with graphical histograms which are used widely in quality control (Q.C.). Histograms are effective Q.C. tools which are used in the analysis of data. They are used as a check on specific process parameters to determine where the greatest amount of variation occurs in the process, or to determine if process specifications are exceeded. This statistical method does not prove that a process is in a state of control. Nonetheless, histograms alone have been used to solve many problems in quality control.
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Key Terms: Histogram A vertical bar chart of a frequency distribution of data Q.C. Methodology A statistical tool used in the analysis and determination of possible solutions to quality control problems in industry Frequency Distribution A variation in a numeric sample of data
Creating a Histogram 1. Determine the range of the data by subtracting the smallest observed measurement from the largest and designate it as R. 2. Example: 3. Largest observed measurement = 1.1185 inches 4. Smallest observed measurement = 1.1030 inches 5. R = 1.1185 inches - 1.1030 inches =.0155 inch 6. Record the measurement unit (MU) used. This is usually controlled by the measuring instrument least count. 7. Example: MU = .0001 inch 8. Determine the number of classes and the class width. The number of classes, k, should be no lower than six and no higher than fifteen for practical purposes. Trial and error may be done to achieve the best distribution for analysis. 9. Example: k=8 10. Determine the class width (H) by dividing the range, R, by the preferred number of classes, k. 11. Example: R/k = .0155/8 = .0019375 inch 12. The class width selected should be an odd-numbered multiple of the 13. Measurement unit, MU. This value should be close to the H value: 14. MU = .0001 inch 15. Class width = .0019 inch or .0021 inch 16. Establish the class midpoints and class limits. The first class midpoint should be located near the largest observed measurement. If possible, it should also be a convenient increment. Always make the class widths equal in size and express the class limits in terms which are one-half unit beyond the accuracy of the original measurement unit. This avoids plotting an observed measurement on a class limit. 17. Example: First class midpoint = 1.1185 inches, and the 18. Class width is .0019 inch. Therefore, limits would be 19. 1.1185 + or - .0019/2. 20. Determine the axes for the graph. The frequency scale on the vertical axis should slightly exceed the largest class frequency, and the measurement scale along the horizontal axis should be at regular intervals which are independent of the class width. (See example below steps.) 21. Draw the graph. Mark off the classes, and draw rectangles with heights corresponding to the measurement frequencies in that class.
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22. Title the histogram. Give an overall title and identify each axis.
Interpretations When combined with the concept of the normal curve and the knowledge of a particular process, the histogram becomes an effective, practical working tool in the early stages of data analysis. A histogram may be interpreted by asking three questions: 1. Is the process performing within specification limits? 2. Does the process seem to exhibit wide variation? 3. If action needs to be taken on the process, what action is appropriate? The answer to these three questions lies in analyzing three characteristics of the histogram. 1. How well is the histogram centred? The centring of the data provides information on the process aim about some mean or nominal value. 2. How wide is the histogram? Looking at histogram width defines the variability of the process about the aim. 3. What is the shape of the histogram? Remember that the data is expected to form a normal or bell-shaped curve. Any significant change or anomaly usually indicates that there is something going on in the process which is causing the quality problem.
Examples of Typical Distributions NORMAL
•
Depicted by a bell-shaped curve o most frequent measurement appears as centre of distribution o less frequent measurements taper gradually at both ends of distribution
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Indicates that a process is running normally (only common causes are present).
BI-MODAL
• •
Distribution appears to have two peaks May indicate that data from more than process are mixed together o materials may come from two separate vendors o Samples may have come from two separate machines.
CLIFF-LIKE
• •
Appears to end sharply or abruptly at one end Indicates possible sorting or inspection of non-conforming parts.
SAW-TOOTHED
• •
Also commonly referred to as a comb distribution, appears as an alternating jagged pattern Often indicates a measuring problem o improper gage readings o Gage not sensitive enough for readings.
SKEWED
Appears as an uneven curve; values seem to taper to one side. It is worth mentioning again that this or any other phase of histogram analysis must be married to knowledge of the process being studied to have any real value. Knowledge of the data analysis itself does not provide sufficient insight into the quality problem. •
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OTHER CONSIDERATIONS Number of samples. For the histogram to be representative of the true process behaviour, as a general rule, at least fifty (50) samples should be measured.
Limitations of techniques. Histograms are limited in their use due to the random order in which samples are taken and lack of information about the state of control of the process. Because samples are gathered without regard to order, the time-dependent or time-related trends in the process are not captured. So, what may appear to be the central tendency of the data may be deceiving. With respect to process statistical control, the histogram gives no indication whether the process was operating at its best when the data was collected. This lack of information on process control may lead to incorrect conclusions being drawn and, hence, inappropriate decisions being made. Still, with these considerations in mind, the histogram's simplicity of construction and ease of use make it an invaluable tool in the elementary stages of data analysis.
Example The following example shows data collected from an experiment measuring pellet penetration depth from a pellet drill machine in inches and the corresponding histogram: Penetration depth (inches)- 2,3,3,3,3,4,4,4,5,5,6,6.
Some important things to remember when constructing a histogram: • Use intervals of equal length. • Show the entire vertical axes beginning with zero. • Do not break either axis. • Keep a uniform scale across the axis. • Centre the histogram bars at the midpoint of the intervals (in this case, the penetration depth intervals).
FLOW CHARTS OVERVIEW Quality Improvement Tool: Flow charts used specifically for a process. A flow chart is defined as a pictorial representation describing a process being studied or even used to plan stages of a project. Flow charts tend to provide people with a common language or reference point when dealing with a project or process. Four particular types of flow charts have proven useful when 23
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dealing with a process analysis: top-down flow chart, detailed flow chart, work flow diagrams, and a deployment chart. Each of the different types of flow charts tends to provide a different aspect to a process or a task. Flow charts provide an excellent form of documentation for a process, and quite often are useful when examining how various steps in a process work together. When dealing with a process flow chart, two separate stages of the process should be considered: the finished product and the making of the product. In order to analyze the finished product or how to operate the process, flow charts tend to use simple and easily recognizable symbols. The basic flow chart symbols below are used when analyzing how to operate a process.
In order to analyze the second condition for a flow process chart, one should use the ANSI standard symbols. The ANSI standard symbols used most often include the following:
Drive Nail, Cement, Type Letter.
Move Material by truck, conveyor, or hand.
Raw Material in bins, finished product on pallets, or filed documents.
Wait for elevator, papers waiting, material waiting
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Read gages, read papers for information, or check quality of goods.
Any combination of two or more of these symbols show an understanding for a joint process.
INSTRUCTIONS Step-by-Step process of how to develop a flow chart. • Gather information of how the process flows: use a) conservation, b) experience, or c) product development codes. • Trial process flow. • Allow other more familiar personnel to check for accuracy. • Make changes if necessary. • Compare final actual flow with best possible flow. Note: Process should follow the flow of Step1, Step 2... Step N. Step N= End of Process CONSTRUCTION/INTERPRETATION tip for a flow chart. • Define the boundaries of the process clearly. • Use the simplest symbols possible. • Make sure every feedback loop has an escape. • There is usually only one output arrow out of a process box. Otherwise, it may require a decision diamond.
INTERPRETATION • • •
•
Analyze flow chart of actual process. Analyze flow chart of best process. Compare both charts, looking for areas where they are different. Most of the time, the stages where differences occur is considered to be the problem area or process. Take appropriate in-house steps to correct the differences between the two separate flows.
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Process Flow Chart- How a process works (Assembling of oil-filled buffer)
Cause and Effect Diagram PURPOSE and USAGE To provide a pictorial display of a list in which you identify and organize possible causes of problems, or factors needed to ensure success of some effort. It is an effective tool that allows people to easily see the relationship between factors to study processes, situations, and for planning.
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HISTORICAL BACKGROUND The cause-and-effect diagram is also called the Ishikawa diagram (after its creator, Kaoru Ishikawa of Japan), or the fishbone diagram (due to its shape). It was created so that all possible causes of a result could be listed in such a way as to allow a user to graphically show these possible causes. From this diagram, the user can define the most likely causes of a result. This diagram was adopted by Dr. W. Edwards Deming as a helpful tool in improving quality. Dr. Deming has taught Total Quality Management in Japan since World War II. He has also helped develop statistical tools to be used for the census and taught the military his methods of quality management. Both Ishikawa and Deming use this diagram as one the first tools in the quality management process.
USEFUL SOFTWARE Cause and Effect Diagrams are typically constructed through brainstorming techniques. As a result, they are often drafted by hand on paper. However, two software packages capable of displaying the diagram professionally are AutoCAD and CADKEY.
Control Charts as a tool in SQC (Statistical Quality Control) Overview This page has been designed to help in understanding and learning the use, design and analysis of Control Charts, which is the most important tool of Statistical Quality Control. The information has been formatted in the form of a tutorial, which will guide you through the process. It includes the history, background information, the uses, and the types with examples, analysis of patterns, related software and additional sources of information about control charts.
Background Information A typical control chart is a graphical display of a quality characteristic that has been measured or computed from a sample versus the sample number or time. The chart contains a centre line that represents the average value of the quality characteristic corresponding to the in-control state. Two other horizontal lines, called the upper control limit (UCL) and the lower control limit (LCL) are also drawn. These control limits are chosen so that if the process is in control, nearly all of the sample points will fall between them. As long as the points plot within the control limits, the process is assumed to be in control, and no action is necessary. However, a point that plots outside of the control limits is interpreted as evidence that the process is out of control, and investigation and corrective action is required to find and eliminate the assignable causes responsible for this behavior. The control points are connected with straight line segments for easy visualization. Even if all the points plot inside the control limits, if they behave in a systematic or nonrandom manner, then this is an indication that the process is out of control.
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Uses of Control charts Control chart is a device for describing in a precise manner what is meant by statistical control. Its uses are 1. It is a proven technique for improving productivity. 2. It is effective in defect prevention. 3. It prevents unnecessary process adjustments. 4. It provides diagnostic information. 5. It provides information about process capability.
Types of control charts 1.
2.
Control charts for Attributes. 1. p chart 2. c chart 3. u chart Control charts for Variables. 1. X bar chart 2. R chart
Analysis of Patterns on Control Charts A control chart may indicate an out-of-control condition either when one or more points fall beyond the control limits, or when the plotted points exhibit some non-random pattern of behaviour. The process is out of control if any one or more of the criteria is met. 1. One or more points outside of the control limits. This pattern may indicate: o A special cause of variance from a material, equipment, method, or measurement system change. o Mismeasurement of a part or parts. o Miscalculated or misplotted data points. o Miscalculated or misplotted control limits. 2. A run of eight points on one side of the centre line. This pattern indicates a shift in the process output from changes in the equipment, methods, or materials or a shift in the measurement system. 3. Two of three consecutive points outside the 2-sigma warning limits but still inside the control limits. This may be the result of a large shift in the process in the equipment, methods, materials, or operator or a shift in the measurement system. 4. Four of five consecutive points beyond the 1-sigma limits. 5. An unusual or non random pattern in the data. 1. A trend of seven points in a row upward or downward. This may show Gradual deterioration or wear in equipment. Improvement or deterioration in technique. 2. Cycling of data can indicate Temperature or other recurring changes in the environment. Differences between operators or operator techniques. Regular rotation of machines.
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Differences in measuring or testing devices that are being used in order. 2. Several points near a warning or control limit.
Signs and Symbols Used by the Company at sites The following signs and symbols are used at the site of erection of the elevators. These signs are placed at various necessary places that help the workers as well as the elevator users
The various types of signs and symbols used in the company site during erection of elevators and also during the time of their maintenance.
Acknowledgement How many of our courses teach us to become entrepreneurs? Since childhood it’s been grilled into our head to study hard / score well and get a “Good Job”. 29
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This project has given me an opportunity to be a confident, qualified individual to venture out to be a master of oneself and our lives. This is a field where we on our own start a venture with clear vision, of the direction to be taken both for the activities as well as to guide the people working under. If a TATA, BAJAJ, MAHINDRA can become household name, so can we with a clear vision, sense and meaning can emulate over time. According to me, an entrepreneur is the one who has an idea with the will of being different and has the capacity to take risks in his life. I feel that there is an entrepreneur in all those people who think larger than life and who have the employer mind set and believe in following their heart. An entrepreneur is the one who ignores the trend, does not say “me too” and becomes a trend setter by starting a new and unique business which makes a difference in the world.
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Natraj Korgaonkar S.Y.B.M.S. (A) - 46
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Elevator Industry with Special Emphasis on “Otis”
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Our Company OTIS-World's Largest... Otis is the world’s largest manufacturer of elevators, escalators, moving walks and other horizontal transportation systems. For architects and contractors, developers and homeowners, Otis is the world’s leading people mover. While we manufacture, install, modernize and maintain elevators, escalators, moving walks and shuttles, the heart of our business is problem solving. Whether a customer needs a sophisticated elevator system for the tallest building in the world or a simple lift for a two-story home, we are dedicated to providing the safest, most reliable solutions possible. Changing the shape of the world In 1853, Elisha Graves Otis introduced the world’s first safety elevator in Yonkers, New York —changing the shape of the modern world. From that point forward, buildings could rise beyond the limitations of stairs. Cities would have skylines. Today, our pioneering spirit is as strong as it was when we began. With every new product and service, Otis is moving our industry, our company and our customers forward. Sharing strengths Otis is part of United Technologies Corporation, a Fortune 500 company and world leader in the building systems and aerospace industries. Sharing strengths with UTC allows Otis to draw on remarkable resources in engineering, product testing, purchasing, marketing and information systems. Otis brings all these strengths to bear in creating better solutions for our customers.
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Safety first… The vertical transportation of people and materials to otherwise unobtainable heights was extremely hazardous until Elisha Graves Otis invented the “Elevator safety” in 1852. For ages, man had struggled with various means to transport heavy loads to higher places. By today’s standards, all were unsafe and most unsuccessful. Otis’ safety consisted of a wagon spring and a rack with teeth (ratchet) on the guide rails. If the hoist rope broke, the tension was released from the wagon spring allowing it to engage the ratchet and bring the car to a stop. The pioneering work of Elisha Graves Otis was carried by his sons, Charles and Norton. Many refinement have followed, but the concept is still “Safety First”.
Mr.Elisha Graves Otis displaying the first elevator.
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Products: Otis has mastered itself in the field of elevators since 1852. Ever since Mr. Otis introduced the first elevator to the world, there has been development carried through ages. Otis Elevator has now three main categories of products with different models in each section. They are as follows: Traction Elevators Hydraulic Elevators Escalators Each of these sections has around 200 models varying upon the capacity, the type of load being carried in the elevator, the height of the building, the speed required by customer and so. Again each of these categories has two main sub-groups: Passenger Elevators Cargo/ goods Elevators.
The elevator from outside.
The Escalator.
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Production Process The design and production of any of the elevators is done in Taiwan and in Korea. Unfortunately there is no Elevator company in India which has a production plant or factory in the country. All the companies along with Otis have their design and production plants outside the country. They only assemble and re-engineer the product at the site where the elevator has to be erected. This helps in saving a lot of technological cost because the company fins the technology cheap in the foreign markets. And thus only importing the required parts becomes cheaper in India that producing elevators. All the parts of the elevator or escalators are imported stored in the country. Otis Elevators has its own stores department and an official head office in Mumbai at Nepensea Road and Kandivli respectively. Thus as per the requirements of the workers working at various sites of the company the required goods or spare parts or the equipments are delivered to the site of erection or maintenance or both. Currently the company undertakes jobs or erection of elevators and escalators at various new places and maintenance of erected elevators. At times this may also include elevators produced by different companied for which Otis charges fee plus compensation.
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Process of Erection of Elevators with Time and Work Measurement: As said earlier the company does not indulge itself in the production of elevators in India and thus it imports all its requirements from its parent company across the globe, the company has a low cost advantage. Thus the company only takes orders from their clients and then order for the same and then erects the elevator or escalators at the site given to them. Following is the synopsis of the erection process of elevators: • Order: The order of the product is the first main stage of the erection of an elevator. As per the clients’ requirements for the type of elevator, size composition, cost analysis maintenance etc, the company advices the clients for any change if required in the order. The time taken for this process depends upon the negotiations and the company and the clients’ relationship. •
Company’s requirements: As per the clients’ requirements the company places its requirement of the hall way that would be required where the elevator would be place, the place and the area of the machine room, the pit- its depth, area, electricity connections, scaff-holding, shafts, etc. The time taken to complete all the company’s requirements would be the time taken by the builder to complete the main structure of the building. This would again depend upon the height of the building. •
Actual erection process: After the clients have given the company’s basic requirements that are necessary for erecting an elevator the actual process of erection begins. This starts with building the scaff-holdings (bamboo building structure) inside the hall way where one places the elevator and setting-up the machine room with the machine motor, brake assembly, controller, governor and then the work to construct the shaft begins. •
Combined work forces: By the time the machine room is set, other group of workers start setting up the hall buttons, landing doors on each floor, fixtures and assembling the pit just below the ground floor. The setting-up of the pit is the most important factor. This is the one which allows the car-lift to rest and prevent it from going further underground. In other words, it prevents free-fall of the car-lift by the use of counter buffer and oilbuffers. The time taken for the same process is same as the above as both the works is done at the same time.
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•
Assembling of the main car-lift: This the next stage in the erection of the car-lift in the hall-way. This is done by first setting-up the guide rails which are about 16m each in height. These are done upto the ceiling roof. Then the car-lift is set-up at the top floor with the counterweight on the ground floor. This is the main principle stage for the working of the elevator. If there is even a single mistake in determining the counterweight or assembling it right, the then whole elevator will crash within a second. If there is a perfect balance then the steel ropes are attached to the car-lift and the counterweight through the machine motor situated on the terrace just over the hall-way. Since this is the most crucial stage, takes around 8-10 days (for 6 storeyed building) depending upon the height of the building. •
Fixtures and buttons: After setting-up the main frame of he elevator, the next stage is setting up the fixture, buttons in the car-lift, coordinating open and close doors at each and every floor, testing each floor for reciprocal call etc. Sine this is minute but energy consuming process takes at least 6-8 days for a normal 6 storeyed building
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Management by Objectives Definition: -‘Management by Objectives’ is a comprehensive managerial system that integrates many key managerial activities in a systematic manner and that is consciously directed towards the effective and efficient achievement of organizational and individual objectives.
Evolving Concepts in MBO: • Early Impetus to MBO: Since many centuries people have used their common sense and given importance to management by objectives. It was in 1954 that Peter. F. Drucker first emphasized that objectives must be set in all areas where performance affects the health of the enterprise. About at the same time General Electric Co. was using MBO in its reorganization • Emphasis On Performance Appraisal: In traditional appraisal programs personality traits were used for evaluating subordinates. But when MBO was implemented emphasis was given on performance rather than personality which lead to self appraisal and self development. The active involvement of subordinates leads to commitment and creates an environment for motivation.
Emphasis on short-term objectives and motivation: Individual goal setting is an important factor in motivating employees. It is known that performance is higher when people have specific objectives than when they are asked simply to do their best.
• Inclusion Of Long Range Plan In MBO:
In MBO programs that emphasis performance appraisals and motivation the focus tends to be on short term objectives, which may lead to undesirable managerial behaviour. Due to these short-comings many organization now include long range and strategic planning in MBO programs. •
The System Approach To MBO MBO has undergone many changes. It has been used in performance appraisals as an instrument for motivating individual and in strategic planning. But there are still other managerial subsystems that can be integrated into MBO process. Various managerial activities need to be integrated into a system. For MBO to be a comprehensive system of managing indicates that most key managerial activities can and should be integrated with the MBO process. The degree of integration however differs for individual activities. For MBO to be effective it has to be viewed as a comprehensive system and it must be considered as a way of managing and not an addiction to the managerial job.
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The Process of Managing By Objectives: The process starts at the top of an organization and has the active support of the chief executive, who gives direction to the organization. It is not essential the objective setting starts at the top. It can start at the divisional level, at the marketing level or even lower level. As in all planning, one of the critical need in MBO is the development and dissemination of consistent planning premises. No manager can be expected to set goals or establish plans and budgets without guidelines.
Setting preliminary objectives at the top: Given appropriate planning premises, the first step in setting objectives is for the top manager to determine what he or she perceives to be the purpose or mission and the more important goals of the enterprise for a given period ahead. Certain goals should be scheduled for accomplishment in a much shorter period and others in a much longer period. The goals set by the superior are preliminary based on an analysis and judgment as to what can and should be accomplished by the organization within a certain period. This requires taking into account the company’s strength and weakness in the light of available opportunities and threats. Most managers also find out the process of working out goals with the subordinates reveals both problems they should deal with and the opportunities they were not previously aware of. When setting objectives, the manager also establishes measure of goal accomplishment. If verifiable objectives are developed, these measures, whether in sale dollars profits, percentages, cost level, or program execution, will normally built into objectives.
Clarifying Organizational Roles: The relationship between expected results and the responsibility of attaining is often overlooked. Ideally, each goal and sub goal should be one particular person’s responsibility. Analyzing an organization structure, however, often reveals that the responsibility is vague and the clarification or reorganization is needed. Sometimes it is impossible to structure an organization so that a given objective is someone’s personal responsibility.
Setting Subordinates Objectives: After making sure that subordinate managers have been informed of pertinent general objectives, strategies, and planning premises, the superior can then proceed to work with subordinates in setting their objectives. The superiors ask what goals the subordinates believe they can accomplish, in what time period and with what resources. Superiors must also be patient counsellors, helping their subordinates develop consistent and supportive objectives and being careful not to set goals that are impossible to
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achieve. One of the things that can weaken a program by objectives is to allow managers to set unrealistic objectives. One of the major advantages of carefully setting up a network of verifiable goals and a requirement for doing so effectively is trying in the need of capital, materials and human resources at the same time. All managers at all levels require these resources to accomplish their goals. By relating these resources to the goals themselves, superiors can better see the most effective and the most economical way of allocating them
Recycling of objectives: Objectives can hardly be set by starting at the top and dividing them up among subordinates nor should they be started from the bottom. A degree of recycling is a must. Top managers may have some idea of what their subordinates’ objectives should be; but they will almost certainly change these preconceived goals as the contributions of the subordinates come into focus. Thus setting objectives is not a joint process but also an interactive one.
Benefits of Management by Objectives: 1. Improvement of managing: Managing Sense in a Manager Improves. 2. Clarification of organization: Management by objectives forces managers to clarify roles i.e. organizational roles and structures. 3. Encouragement of Personal Commitment: It encourages people to commit themselves to their goals. 4. Development of Effective Controls: MBO helps in effective planning, it also aids in developing effective controls.
Weakness of Management by Objectives: 1. 2. 3. 4. 5.
Failure to teach the philosophy of MBO. Failure to give guidelines to goal setters. Difficulty of setting goals. MBO programs are set for short terms. Danger of inflexibility.
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Total Quality Management or TQM is a management strategy to embed awareness of quality in all organizational processes. Quality assurance through statistical methods is a key component. TQM aims to do things right the first time, rather than need to fix problems after they emerge or fester. TQM may operate within quality circles, which encourage the meeting of minds of the workforce in different departments in order to improve production and reduce wastage. In a Otis, TQM generally starts by sampling a random selection of the product. The sample is then tested for things that matter to the real customers. The causes of any failures are isolated, secondary measures of the production process are designed, and then the causes of the failure are corrected. The statistical distributions of important measurements are tracked. When parts' measures drift out of the error band, the process is fixed. The error band is usually tighter than the failure band. The production process is thereby fixed before failing parts can be produced. It's important to record not just the measurement ranges, but what failures caused them to be chosen. In that way, cheaper fixes can be substituted later, (say, when the produce is redesigned), with no loss of quality. After TQM has been in use, it's very common for parts to be redesigned so that critical measurements either cease to exist, or become much wider. It took people a while to develop tests to find emergent problems. One popular test is a "life test" in which the sample product is operated until a part fails. Another popular test is called "shake and bake". The product is mounted on a vibrator in an environmental oven, and operated at progressively more extreme vibration and temperatures until something fails. The failure is then isolated and engineers design an improvement. A commonly-discovered failure is for the product to come apart. If fasteners fail, the improvements might be to use measured-tension nutdrivers to ensure that screws don't come off, or improved adhesives to ensure that parts remain glued. If a gearbox wears out first, a typical engineering design improvement might be to substitute a brushless stepper motor for a DC motor with a gearbox. The improvement is that a stepper motor has no brushes or gears to wear out, so it lasts ten times or more longer. The stepper motor is more expensive than a DC motor, but cheaper than a DC motor combined with a gearbox. The electronics is radically different, but equally expensive. One disadvantage might be that a stepper motor can hum or whine, and usually needs noise-isolating mounts. Often a TQMed product is cheaper to produce (because there's no need to repair dead-onarrival products), and can yield an immensely more desirable product. TQM can be applied to services (such as mortgage issue or insurance underwriting), or even normal business paperwork. TQM is not a focused improvement approach. The customer desires and product tests select what to fix. Theoretical constraints are not considered at all.
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Scatter Diagrams This tutorial is designed to allow the user to develop and interpret scatter diagrams. When the scatter diagram has been plotted from the data, the user can view several different graphs within the Interpretations, read the interpretation of the diagrams pattern, and be able to draw conclusions about the plotted diagram by comparing it to one of the five possible graph patterns.
Overview Scatter diagrams are used to study possible relationships between two variables. Although these diagrams cannot prove that one variable causes the other, they do indicate the existence of a relationship, as well as the strength of that relationship. A scatter diagram is composed of a horizontal axis containing the measured values of one variable and a vertical axis representing the measurements of the other variable. The purpose of the scatter diagram is to display what happens to one variable when another variable is changed. The diagram is used to test a theory that the two variables are related. The type of relationship that exits is indicated by the slope of the diagram.
Key Terms
Variable - a quality characteristic that can be measured and expressed as a number on some continuous scale of measurement. Relationship - Relationships between variables exist when one variable depends on the other and changing one variable will affect the other. Data Sheet - contains the measurements that were collected for plotting the diagram. Correlation - an analysis method used to decide whether there is a statistically significant relationship between two variables. Regression - an analysis method used to identify the exact nature of the relationship between two variables.
Construction of Scatter Diagrams
Collect and construct a data sheet of 50 to 100 paired samples of data that you suspect to be related. Construct your data sheet as follows: Car (elevator) 1 2 3 4 : : : : 100
Age (In Years) 2 4 1 5 : : : : 7
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Price (In Dollars) 4000 2500 5000 1250 : : : : 1000
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Draw the axes of the diagram. The first variable (the independent variable) is usually located on the horizontal axis and its values should increase as you move to the right. The vertical axis usually contains the second variable (the dependent variable) and its values should increase as you move up the axis. Plot the data on the diagram. The resulting scatter diagram may look as follows:
Interpret the diagram. See interpretation section of tutorial.
Interpretations The scatter diagram is a useful tool for identifying a potential relationship between two variables. The shape of the scatter diagram presents valuable information about the graph. It shows the type of relationship which may be occurring between the two variables. There are several different patterns (meanings) that scatter diagrams can have. The following describe five of the most common scenarios: 1. The first pattern is positive correlation, that is, as the amount of variable x increases, the variable y also increases. It is tempting to think this is a cause/effect relationship. This is an incorrect thinking pattern, because correlation does not necessarily mean causality. This simple relationship could be caused by something totally different. For instance, the two variables could be related to a third, such as curing time or stamping temperature. Theoretically, if x is controlled, we have a chance of controlling y.
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2. Secondly, we have possible positive correlation, that is, if x increases, y will increase somewhat, but y seems to be caused by something other than x. Designed experiments must be utilized to verify causality.
3. We also have the no correlation category. The diagram is so random that there is no apparent correlation between the two variables.
4. There is also possible negative correlation, that is, an increase in x will cause a tendency for a decrease in y, but y seems to have causes other than x.
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5. Finally, we have the negative correlation category. An increase in x will cause a decrease in y. Therefore, if y is controlled, we have a good chance of controlling x.
Key Observations *A strong relationship between the two variables is observed when most of the points fall along an imaginary straight line with either a positive or negative slope. *No relationship between the two variables is observed when the points are randomly scattered about the graph.
RUN CHARTS/TIME PLOT/TREND CHART
PURPOSE In-depth view into Run Charts--a quality improvement technique; how Run charts are used to monitor processes; how using Run charts can lead to improved process quality
USAGE Run charts are used to analyze processes according to time or order. Run charts are useful in discovering patterns that occur over time.
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KEY TERMS Trends: Trends are patterns or shifts according to time. An upward trend, for instance, would contain a section of data points that increased as time passed.
Population: A population is the entire data set of the process. If a process produces one thousand parts a day, the population would be the one thousand items.
Sample: A sample is a subgroup or small portion of the population that is examined when the entire population can not be evaluated. For instance, if the process does produce one thousand items a day, the sample size could be perhaps three hundred.
INSTRUCTIONS FOR CREATING A CHART Step 1: Gathering Data To begin any run chart, some type of process or operation must be available to take measurements for analysis. Measurements must be taken over a period of time. The data must be collected in a chronological or sequential form. You may start at any point and end at any point. For best results, at least 25 or more samples must be taken in order to get an accurate run chart.
Step 2: Organizing Data Once the data has been placed in chronological or sequential form, it must be divided into two sets of values x and y. The values for x represent time and the values for y represent the measurements taken from the manufacturing process or operation.
Step 3: Charting Data Plot the y values versus the x values by hand or by computer, using an appropriate scale that will make the points on the graph visible. Next, draw vertical lines for the x values to separate time intervals such as weeks. Draw horizontal lines to show where trends in the process or operation occur or will occur.
Step 4: Interpreting Data After drawing the horizontal and vertical lines to segment data, interpret the data and draw any conclusions that will be beneficial to the process or operation. Some possible outcomes are: • Trends in the chart • Cyclical patterns in the data • Observations from each time interval are consistent
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RUN CHART EXAMPLE Problem Scenario We use the run chart for data analysis of workers time-in and time-out. This is illustrated in the given data where we have shown the days and time taken by a worker to reach his office.
Step 1: Gathering Data Collect measurements each day over the next four weeks. Organize and record the data in chronological or sequential form. M WEEK WEEK WEEK WEEK
1 2 3 4
33 35 34.5 34
T 28 30.5 29 29.5
W
TH
26.5 28 28 27
28 26 26 27
F 26 25.5 25 25.5
Step 2: Organizing Data Determine what the values for the x (time, day of week) and day (data, minutes to work) axis will be.
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Step 3: Charting Data Plot the y values versus the x values by hand or by computer using the appropriate scale. Draw horizontal or vertical lines on the graph where trends or inconsistencies occur.
Step 4: Interpreting Data Interpret results and draw any conclusions that are important. An overall decreasing trend occurs each week with Mondays taking the most amounts of time and Fridays generally taking the least amount of time. Therefore you accordingly allow yourself more time on Mondays to arrive to work on time.
Histograms The histogram will provide information on quality process control (Q.C.). The histogram evolved to meet the need for evaluating data that occurs at a certain frequency. This is possible because the histogram allows for a concise portrayal of information in a bar graph format. The histogram is a powerful engineering tool when routinely and intelligently used. The histogram clearly portrays information on location, spread, and shape that enables the user to perceive subtleties regarding the functioning of the physical process that is generating the data. It can also help suggest both the nature of, and possible improvements for, the physical mechanisms at work in the process.
Purpose: The purpose is to become familiar with graphical histograms which are used widely in quality control (Q.C.). Histograms are effective Q.C. tools which are used in the analysis of data. They are used as a check on specific process parameters to determine where the greatest amount of variation occurs in the process, or to determine if process specifications are exceeded. This statistical method does not prove that a process is in a state of control. Nonetheless, histograms alone have been used to solve many problems in quality control.
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Key Terms: Histogram A vertical bar chart of a frequency distribution of data Q.C. Methodology A statistical tool used in the analysis and determination of possible solutions to quality control problems in industry Frequency Distribution A variation in a numeric sample of data
Creating a Histogram 1. Determine the range of the data by subtracting the smallest observed measurement from the largest and designate it as R. 2. Example: 3. Largest observed measurement = 1.1185 inches 4. Smallest observed measurement = 1.1030 inches 5. R = 1.1185 inches - 1.1030 inches =.0155 inch 6. Record the measurement unit (MU) used. This is usually controlled by the measuring instrument least count. 7. Example: MU = .0001 inch 8. Determine the number of classes and the class width. The number of classes, k, should be no lower than six and no higher than fifteen for practical purposes. Trial and error may be done to achieve the best distribution for analysis. 9. Example: k=8 10. Determine the class width (H) by dividing the range, R, by the preferred number of classes, k. 11. Example: R/k = .0155/8 = .0019375 inch 12. The class width selected should be an odd-numbered multiple of the 13. Measurement unit, MU. This value should be close to the H value: 14. MU = .0001 inch 15. Class width = .0019 inch or .0021 inch 16. Establish the class midpoints and class limits. The first class midpoint should be located near the largest observed measurement. If possible, it should also be a convenient increment. Always make the class widths equal in size and express the class limits in terms which are one-half unit beyond the accuracy of the original measurement unit. This avoids plotting an observed measurement on a class limit. 17. Example: First class midpoint = 1.1185 inches, and the 18. Class width is .0019 inch. Therefore, limits would be 19. 1.1185 + or - .0019/2. 20. Determine the axes for the graph. The frequency scale on the vertical axis should slightly exceed the largest class frequency, and the measurement scale along the horizontal axis should be at regular intervals which are independent of the class width. (See example below steps.) 21. Draw the graph. Mark off the classes, and draw rectangles with heights corresponding to the measurement frequencies in that class.
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22. Title the histogram. Give an overall title and identify each axis.
Interpretations When combined with the concept of the normal curve and the knowledge of a particular process, the histogram becomes an effective, practical working tool in the early stages of data analysis. A histogram may be interpreted by asking three questions: 1. Is the process performing within specification limits? 2. Does the process seem to exhibit wide variation? 3. If action needs to be taken on the process, what action is appropriate? The answer to these three questions lies in analyzing three characteristics of the histogram. 1. How well is the histogram centred? The centring of the data provides information on the process aim about some mean or nominal value. 2. How wide is the histogram? Looking at histogram width defines the variability of the process about the aim. 3. What is the shape of the histogram? Remember that the data is expected to form a normal or bell-shaped curve. Any significant change or anomaly usually indicates that there is something going on in the process which is causing the quality problem.
Examples of Typical Distributions NORMAL
•
Depicted by a bell-shaped curve o most frequent measurement appears as centre of distribution o less frequent measurements taper gradually at both ends of distribution
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Indicates that a process is running normally (only common causes are present).
BI-MODAL
• •
Distribution appears to have two peaks May indicate that data from more than process are mixed together o materials may come from two separate vendors o Samples may have come from two separate machines.
CLIFF-LIKE
• •
Appears to end sharply or abruptly at one end Indicates possible sorting or inspection of non-conforming parts.
SAW-TOOTHED
• •
Also commonly referred to as a comb distribution, appears as an alternating jagged pattern Often indicates a measuring problem o improper gage readings o Gage not sensitive enough for readings.
SKEWED
Appears as an uneven curve; values seem to taper to one side. It is worth mentioning again that this or any other phase of histogram analysis must be married to knowledge of the process being studied to have any real value. Knowledge of the data analysis itself does not provide sufficient insight into the quality problem. •
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OTHER CONSIDERATIONS Number of samples. For the histogram to be representative of the true process behaviour, as a general rule, at least fifty (50) samples should be measured.
Limitations of techniques. Histograms are limited in their use due to the random order in which samples are taken and lack of information about the state of control of the process. Because samples are gathered without regard to order, the time-dependent or time-related trends in the process are not captured. So, what may appear to be the central tendency of the data may be deceiving. With respect to process statistical control, the histogram gives no indication whether the process was operating at its best when the data was collected. This lack of information on process control may lead to incorrect conclusions being drawn and, hence, inappropriate decisions being made. Still, with these considerations in mind, the histogram's simplicity of construction and ease of use make it an invaluable tool in the elementary stages of data analysis.
Example The following example shows data collected from an experiment measuring pellet penetration depth from a pellet drill machine in inches and the corresponding histogram: Penetration depth (inches)- 2,3,3,3,3,4,4,4,5,5,6,6.
Some important things to remember when constructing a histogram: • Use intervals of equal length. • Show the entire vertical axes beginning with zero. • Do not break either axis. • Keep a uniform scale across the axis. • Centre the histogram bars at the midpoint of the intervals (in this case, the penetration depth intervals).
FLOW CHARTS OVERVIEW Quality Improvement Tool: Flow charts used specifically for a process. A flow chart is defined as a pictorial representation describing a process being studied or even used to plan stages of a project. Flow charts tend to provide people with a common language or reference point when dealing with a project or process. Four particular types of flow charts have proven useful when 23
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dealing with a process analysis: top-down flow chart, detailed flow chart, work flow diagrams, and a deployment chart. Each of the different types of flow charts tends to provide a different aspect to a process or a task. Flow charts provide an excellent form of documentation for a process, and quite often are useful when examining how various steps in a process work together. When dealing with a process flow chart, two separate stages of the process should be considered: the finished product and the making of the product. In order to analyze the finished product or how to operate the process, flow charts tend to use simple and easily recognizable symbols. The basic flow chart symbols below are used when analyzing how to operate a process.
In order to analyze the second condition for a flow process chart, one should use the ANSI standard symbols. The ANSI standard symbols used most often include the following:
Drive Nail, Cement, Type Letter.
Move Material by truck, conveyor, or hand.
Raw Material in bins, finished product on pallets, or filed documents.
Wait for elevator, papers waiting, material waiting
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Read gages, read papers for information, or check quality of goods.
Any combination of two or more of these symbols show an understanding for a joint process.
INSTRUCTIONS Step-by-Step process of how to develop a flow chart. • Gather information of how the process flows: use a) conservation, b) experience, or c) product development codes. • Trial process flow. • Allow other more familiar personnel to check for accuracy. • Make changes if necessary. • Compare final actual flow with best possible flow. Note: Process should follow the flow of Step1, Step 2... Step N. Step N= End of Process CONSTRUCTION/INTERPRETATION tip for a flow chart. • Define the boundaries of the process clearly. • Use the simplest symbols possible. • Make sure every feedback loop has an escape. • There is usually only one output arrow out of a process box. Otherwise, it may require a decision diamond.
INTERPRETATION • • •
•
Analyze flow chart of actual process. Analyze flow chart of best process. Compare both charts, looking for areas where they are different. Most of the time, the stages where differences occur is considered to be the problem area or process. Take appropriate in-house steps to correct the differences between the two separate flows.
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Process Flow Chart- How a process works (Assembling of oil-filled buffer)
Cause and Effect Diagram PURPOSE and USAGE To provide a pictorial display of a list in which you identify and organize possible causes of problems, or factors needed to ensure success of some effort. It is an effective tool that allows people to easily see the relationship between factors to study processes, situations, and for planning.
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HISTORICAL BACKGROUND The cause-and-effect diagram is also called the Ishikawa diagram (after its creator, Kaoru Ishikawa of Japan), or the fishbone diagram (due to its shape). It was created so that all possible causes of a result could be listed in such a way as to allow a user to graphically show these possible causes. From this diagram, the user can define the most likely causes of a result. This diagram was adopted by Dr. W. Edwards Deming as a helpful tool in improving quality. Dr. Deming has taught Total Quality Management in Japan since World War II. He has also helped develop statistical tools to be used for the census and taught the military his methods of quality management. Both Ishikawa and Deming use this diagram as one the first tools in the quality management process.
USEFUL SOFTWARE Cause and Effect Diagrams are typically constructed through brainstorming techniques. As a result, they are often drafted by hand on paper. However, two software packages capable of displaying the diagram professionally are AutoCAD and CADKEY.
Control Charts as a tool in SQC (Statistical Quality Control) Overview This page has been designed to help in understanding and learning the use, design and analysis of Control Charts, which is the most important tool of Statistical Quality Control. The information has been formatted in the form of a tutorial, which will guide you through the process. It includes the history, background information, the uses, and the types with examples, analysis of patterns, related software and additional sources of information about control charts.
Background Information A typical control chart is a graphical display of a quality characteristic that has been measured or computed from a sample versus the sample number or time. The chart contains a centre line that represents the average value of the quality characteristic corresponding to the in-control state. Two other horizontal lines, called the upper control limit (UCL) and the lower control limit (LCL) are also drawn. These control limits are chosen so that if the process is in control, nearly all of the sample points will fall between them. As long as the points plot within the control limits, the process is assumed to be in control, and no action is necessary. However, a point that plots outside of the control limits is interpreted as evidence that the process is out of control, and investigation and corrective action is required to find and eliminate the assignable causes responsible for this behavior. The control points are connected with straight line segments for easy visualization. Even if all the points plot inside the control limits, if they behave in a systematic or nonrandom manner, then this is an indication that the process is out of control.
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Uses of Control charts Control chart is a device for describing in a precise manner what is meant by statistical control. Its uses are 1. It is a proven technique for improving productivity. 2. It is effective in defect prevention. 3. It prevents unnecessary process adjustments. 4. It provides diagnostic information. 5. It provides information about process capability.
Types of control charts 1.
2.
Control charts for Attributes. 1. p chart 2. c chart 3. u chart Control charts for Variables. 1. X bar chart 2. R chart
Analysis of Patterns on Control Charts A control chart may indicate an out-of-control condition either when one or more points fall beyond the control limits, or when the plotted points exhibit some non-random pattern of behaviour. The process is out of control if any one or more of the criteria is met. 1. One or more points outside of the control limits. This pattern may indicate: o A special cause of variance from a material, equipment, method, or measurement system change. o Mismeasurement of a part or parts. o Miscalculated or misplotted data points. o Miscalculated or misplotted control limits. 2. A run of eight points on one side of the centre line. This pattern indicates a shift in the process output from changes in the equipment, methods, or materials or a shift in the measurement system. 3. Two of three consecutive points outside the 2-sigma warning limits but still inside the control limits. This may be the result of a large shift in the process in the equipment, methods, materials, or operator or a shift in the measurement system. 4. Four of five consecutive points beyond the 1-sigma limits. 5. An unusual or non random pattern in the data. 1. A trend of seven points in a row upward or downward. This may show Gradual deterioration or wear in equipment. Improvement or deterioration in technique. 2. Cycling of data can indicate Temperature or other recurring changes in the environment. Differences between operators or operator techniques. Regular rotation of machines.
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Differences in measuring or testing devices that are being used in order. 2. Several points near a warning or control limit.
Signs and Symbols Used by the Company at sites The following signs and symbols are used at the site of erection of the elevators. These signs are placed at various necessary places that help the workers as well as the elevator users
The various types of signs and symbols used in the company site during erection of elevators and also during the time of their maintenance.
Acknowledgement How many of our courses teach us to become entrepreneurs? Since childhood it’s been grilled into our head to study hard / score well and get a “Good Job”. 29
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This project has given me an opportunity to be a confident, qualified individual to venture out to be a master of oneself and our lives. This is a field where we on our own start a venture with clear vision, of the direction to be taken both for the activities as well as to guide the people working under. If a TATA, BAJAJ, MAHINDRA can become household name, so can we with a clear vision, sense and meaning can emulate over time. According to me, an entrepreneur is the one who has an idea with the will of being different and has the capacity to take risks in his life. I feel that there is an entrepreneur in all those people who think larger than life and who have the employer mind set and believe in following their heart. An entrepreneur is the one who ignores the trend, does not say “me too” and becomes a trend setter by starting a new and unique business which makes a difference in the world.
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