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Industrial Engineering integrates knowledge and skills from several fields of science: From the Technical Sciences, Economic Sciences as well as Human Science - all these can also be supported with skills in Information Sciences. The Industrial Engineer comprehends knowledge in those sciences in order to increase the productivity of processes, achieve quality products and assures Labor safety

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Standard of living

• The extent to which a person is able to provide the things that are necessary for sustaining and enjoying life.

• Standard of living of a representative family differs greatly in different parts of the world.

• What is considered a necessity in one part of the world could be considered a luxury in the other.

• Basic necessities of a minimum decent standard of living: Food, clothing, housing and hygiene. Also, security and education also considered constituents.

• Greater the amount of goods and services produced in any community, the higher its the average standard of living.

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Standard of living

• There are two ways of increasing the amount of goods and services produced:

- Increase the employment and investment in creating jobs. So that more people are producing goods required for the society.

- Increase productivity. Same amount of labor produces more goods.

We want:• More and cheaper food by increase in agricultural productivity• More and cheaper clothing and housing by increased industrial

productivity• More hygiene, security and education by increasing overall

productivity.

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Productivity

• Ratio between output and input.

• Arithmetic ratio of the amount produced to the amount of any resources used in the production.

• The resources may be: land, material, plant, machines, tools, labor. It could be combination of all!

• Over a period of time, one can say that productivity has increased.

• How?

• Combination of improved technology, better planning, greater skills etc.

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Productivity

• Note that, increased production does not mean increased productivity.

• Higher productivity means that more is produced with the same expenditure of resources; that is, at the same cost in terms of land, material, machine, time or labor.

• Alternatively, same amount is produced at less cost in terms of land, labor, material etc; thereby releasing some of these resources for the production of other things.

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Productivity and standard of living

• If more is available at the same cost, or the same amount is available at lesser cost the whole community benefits.

• As per the ILO, higher productivity provides ways for raising the standard of living by:

1. Larger supplies of both consumer goods and capital goods at lower cost and prices

2. Higher real earnings3. Improvement in working conditions, e.g. by reduced working

hours4. In general, strengthening of the economic foundations of

human well-being.

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Productivity in industry

• Many factors affecting productivity of each organization; also, they are dependent.

• Depending on the individual environments, decisions are to be made.

• Industries where labor and capital costs are low compared to the material costs, better use of material and plant gives the greatest scope of cost reduction.

• In countries where capital and skilled labor are in shortage compared to unskilled labor, one should look to increase the output per machine or per skilled worker.

• Increasing the number of unskilled workers may be beneficial if by doing so an expensive machine or skilled craftsmen are enabled to increase production.

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Government’s responsibility

• Government can create conditions favorable to raise productivity. It can:

1. Have a balanced programs of economic development2. Take steps necessary to maintain employment3. Make opportunities for employment.• Last step is specifically important for a developing country

like India.• Government should make provisions for workers who are

going to loose jobs because of technology improvement – training and education programs.

• Example: India’s First Five-Year Plan (1952).

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Management’s responsibility

• The main responsibility for raising productivity in an individual organization lies with the management.

• It can implement productivity programs.

• It can create a positive environment and obtain co-operation of the employees.

• Trade unions should encourage its members to provide such co-operation when the productivity program is beneficial to workers, as well as the organization on the whole.

• We will look at management’s role in increasing productivity of individual resource:

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Productivity of material

At the design stage:• Ensure least consumption of material,• Purchase equipments and plants such that consumption of

material is economical.

At the operation stage: • Use of correct process• Right use of the process• Operator training• Proper handling and storage of products at all stages• Proper packaging to reduce damage in transit

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Productivity of land, machines and manpower

• Effective utilization and maximum productivity is an important source of cost reduction.

• Reduction in the original specification, before the land is purchased saves capital outlay (as well as interest expenses)

• A savings in material which has to be imported saves import duty and excise.

• Productivity of manpower and machines is typically measured in terms of time (man-hours; machine-hours).

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Factors tending to reduce productivity

Work content added due to the product for a manufacturing firm:

• The product or its components are designed such that it is impossible to use most economical manufacturing processes.

• Excessive variety or lack of standardization.

• Incorrect quality standards.

• Excessive amount of material removal required.

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Work content added due to process

• Incorrect production process (and/or machine) used

• Process not operated properly

• Non-optimal layout with wasted movements.

• Working methods of operation causing wasted movements, time and efforts.

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Ineffective time due to management• Marketing policy which demands unnecessarily large number

of products.• No standardization of components between as well as within

products.• Failing to meet customer’s requirement from the beginning.• No plan for flow of work.• Improper supply of material, equipment.• Improper maintenance of plant and machines.• Insufficient safety measures.• Improper working conditions resulting in interrupted work.

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Ineffective time within the control of worker

• Taking time off without good cause: by lateness, by idling at work etc.

• Careless workmanship causing scrap or rework.

• Failing to observe safety standards.

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Management techniques to reduce work content

Nature of management

• Management is the organization and control of human activity directed towards specific ends.

• Management techniques are systematic procedures of investigation, planning and control which can be applied to management problems.

• Systematic approach to the solution of the problems proceeds step by step from known to the unknown, always on the basis of ascertained facts.

• Since management deals with human beings, it can never be completely scientific, and must partly be regarded as an art.

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Reduce work content due to the product

• Coupling of product design and process design phases (design products such that most economical processes can be used).

• Pilot project/ prototyping to avoid mistakes at a advanced stage (very common in chemical companies).

• Standardization of components.• Setting correct quality standardsStricter standards lead to increased manufacturing time, lenient

standards lead to greater variability.• Knowing the customer – Management should conduct market

research and consumer surveys to know the customer better.

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Reduce work content due to the method

• Process planning – Identification of correct machines for the process. In chemical industry, this is specified by the R&D division or the license seller.

• Process research – Identification of best manufacturing technique.

• Proper maintenance.• Method study – Combine with process planning to give most

suitable tools for the operative. Includes factory layout, working methods of the operative.

• Operator training – Improve working methods of the operative.

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Reduce ineffective time due to the management

• Strategic decisions – Which markets to enter can affect ineffective time to a great extent.

• Production planning – It is planning of proper programs of work so that plant and workers are kept supplied without having to wait.

• Proper programs should be applied only on the basis of sound standards of performance.

• Work measurement – Setting up those standards.• Material control – Workers and machines should not be idle

because of non-availability of material and tools.

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Reduce ineffective time within control of the worker

• Training.• Make worker want to reduce ineffective time. (Create

conditions to make the worker get on with his work. Hawthorne effect)

• Effective personnel policy and management’s attitude towards the worker.

• Good relationship between management and worker.• A sound wage structure, including incentive schemes

(typically based on time standards derived from work measurement).

• SAM : Standard Allowed Minutes• SMV : Standard Minute Value• Man Minutes/man hours• Machine hours• Production Capacity:• No. of Garments• Tech. Pack• PFD• Lead Time• Pitch time• Through put time• WIP• Bottleneck• Floater• Operator• Helper• Productivity 22

Machine Down TimeUPSProduction SystemsMaterial FlowLine balancingLine SetupBundle size and typeTicketingQuality sampling plansAcceptance numberRejection numberAQLCOPQObserved timeNormal/basic timeAllowancesDirect WorkersIndirect Workers

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Work study

• Technique used in the examination of human work in all contexts, and which lead systematically to the investigation of all the factors which affect the efficiency and economy of the situation being reviewed, in order to effect improvement.

• Two branches – method study and work measurement.

• Widely known as “time and motion study.”

• Rapid developments after World War II.

• Huge Capital investment, in process R&D may increase productivity. However, it is expensive and time consuming.

• Work study focuses on human and can increase productivity at a lower cost.

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Work Measurement

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WHY WORK STUDY?Example:• Goal of company: produce 10,000 parts per year• One work centre with multiple servers/operators

will be deployed to establish this goal.• Each part requires three operations to be

produced• All of three operations can be done by the same

server/operator• Company works 2400 hours per year

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• How long does each operation take? (Work measurement)

• Time Study Results: (operation times in minutes)

• Operation 1 Operation 2 Operation 3

5 min. 10 min. 12 min.

• In total, to produce one part, it takes 27 min. in one server

• How many servers/Operators required?

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• Work centre with one server/Operator can produce in one year:

2400 X 60

-------------- = 5333 Parts

27 Min/part

• Required Production = 10000 parts• Hence No. of servers/operators required is

10000 parts

---------------- = 1.87 2 servers/operators

5333 parts

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• Suppose if demand is increased to 15000 parts per year.

• How many servers needed ? • if servers cannot be increased what else can be done?

• Reduce the duration. By what percentage ?

• Goal is to produce 15000 parts per year

2400 hrs/year X 60 Min X 2 servers----------------------------------------------- = 19.2 Min

15000 parts/year

• (27 – 19.2) / 27 Min = 28.8 % But How ?

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Basic procedure of work study

1. Select the job or process to be studied.

2. Record from the direct observations everything that happens.

3. Examine the recorded facts critically and challenge everything that is done.

4. Develop most economic method taking in to considerations all circumstances.

5. Define the new method

6. Measure the quantity of work involved in the method selected and calculate a standard time for doing it..

7. Institutionalize the new method and time as practice.

8. Maintain the new standards by control procedures.

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Work study

• Since line managers are typically busy with the day-to-day activities, they can only look at work study during their free time. They should not be entrusted with the work study responsibilities.

• Workers also ruled out because they usually lack the knowledge of the big picture.

• Therefore, responsibility should be given to someone who can work full-time on work study, without direct management duties.

• Someone in the staff and not a line position.

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Work study: A tool for management

• Means of raising productivity (and efficiency) of the factory by reorganization of work.

• Typically involves low or no capital expenditure.• Systematic process – Covers all aspects of raising

productivity.• Very accurate in setting standards of performance.• Savings from work study start at once and continues as long as

the improved operations are performed.• Applied everywhere: not only in manufacturing shops, offices,

shops, stores, laboratories; and service industries like restaurants, etc.

• One of the most penetrating tools of investigation available to management.

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Work study: Beyond systematic

• Should be applied continuously, and throughout the organization.

• Basis of successful work study: complete intolerance of waste in any form – whether of material, time, effort or human ability.

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Method study

• Method study – Systematic recording and critical examination of existing and proposed ways of doing work, as a means of developing and applying easier and more effective methods and reducing costs.

• Method study is associated with the reduction of the work content of a job or operation, while work measurement is mostly concerned with the investigation and reduction of any ineffective time associated with it.

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Objectives

• Improvement of processes and procedures.• Improvements of factory, shop and workplace layout and of

design of plant and equipment.• Economy of human efforts and the reduction of unnecessary

fatigue.• Improvement in the use of materials, machines and manpower.• The development of a better physical working environment.

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Basic Procedure

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Selecting the work to be studied

• Economic considerationsBottlenecksMovements of material over long distancesOperations involving repetitive work• Technical considerationsRelatively straight forwardBased on the technical knowledge of the process• Human considerationsMost difficult to foretell – because of mental and emotional

nature.Select an unpopular job for method study.

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Important considerations

1. Product and operation2. Person who proposed investigation3. Reason for proposal4. Particulars of the job5. Equipment6. Layout7. Product8. Savings and/or increase in productivity expected.

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Method study charts and diagrams

• Charts indicating process sequence

- Outline process chart

- Flow process chart – Man, Material and Equipment type

- Two-handed process chart

• Charts using a time scale

- Multiple activity chart

- Simo chart

- PMTS chart

• Diagrams indicating movement - Flow diagram - Chronocyclegraph - Sting diagram - Travel chart - Cyclograph

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Method study charts and diagrams

• Outline process chart: Is a process chart giving an overall-picture by recording in sequence only the main operations and inspections.

• Flow process chart: A chart setting out the sequence of flow of a product or a procedure b recording all events under review using the appropriate chart symbols.

Man-type – Records what the worker does

Material-type – Records what happens to materials.

Equipment-type – Records how the equipment is used.

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Flow Diagram

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Man type process flow chart

• A flow process chart which records what the worker does.• Frequently used in the study of jobs which are not highly

repetitive and standardized.• Service and maintenance work, laboratory procedure and

supervisory and executive work can be recorded on this type of chart.

• Since the chart follows one individual or a group performing the same activities in sequence, the standard forms are used.

• Essential to attach a sketch showing the path of movement of the worker while carrying out the operation charted.

• Written in active voice (e.g. worker “drills hole”) as against passive voice of other flow charts (e.g. “hole drilled”).

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String diagram

A scale plan or model on which a thread is used to trace and measure the path of workers, material or equipment during a specified sequence of events.

• A special form of flow diagram, in which a thread is used to measure distance.

• Necessary that the string diagram be drawn correctly to scale, whereas regular flow diagram can be drawn only approximately to scale.

• Start using the string diagram by recording all the relevant facts from direct observation.

• Like flow diagram, it will most often be used to supplement a flow process chart.

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String diagram

• Thus, string diagram and flow chart can give clearest possible picture of what is actually being done.

• Flow process chart will be examined critically in order to make sure that all unnecessary activities are eliminated before a new method is proposed and tested using string diagram.

• String diagram can be used to plot movements of material to know how far the materials travel.

• Most commonly, the string diagram is used for plotting the movements of workers.

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String diagram: Process

• A scale plan of working area similar to that required for a flow diagram must be made; as stated earlier, with higher accuracy.

• Machines, benches, stores etc. should be drawn to scale, together with doorways, pillars, partitions.

• Completed plan should be attached to a softwood board and pins driven into it firmly at every stopping point, the heads being allowed to stand well clear of the surface.

• Pins should also be driven in at all the turning points on the route.

• A measured length of thread is then taken and tied around the pin at the starting point of the movements.

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String diagram: Process

• It is then led around the pins at the other points of call in the order noted on the study sheet until all the movements have been dealt with.

• The result is to give a picture of the paths of movement of the operators, those which are most frequently traversed being covered with the greatest number of strings.

• By measuring the length of the thread, the distance traveled by the worker can be calculated.

• Of two or more workers are studied over the same working area, different colored threads may be used to distinguish them.

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String diagram: Analysis

• Examination of diagram and development of new layout done in a similar fashion as with a flow diagram.

• Pins and templates are moved around until an arrangement is found by which the same operation can be performed with a minimum movement between them.

• This can be checked by leading the thread around the pins in their new positions, keeping the same sequence.

• The length of the thread for the new layout is measured and compared with the length of thread for original layout.

• Difference in length of threads represent the reduction in distance traveled as a result of improved layout.

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Travel chart

• String diagrams take a rather long time to construct. And when a great many movements along complex paths are involved, the diagram looks like ugly mess of criss-crossing lines.

• When the movement patterns are complex, the travel chart is quicker and more manageable recording technique.

• It is a tabular record for presenting quantitative data about movements of workers, materials or equipment between any number of places over any given period of time.

• It is represented as a square matrix: columns indicating origin of movement and rows the destination. Or vice versa.

• Data could be travel time taken, distance traveled etc.

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Travel chart

• The person conducting the study doesn’t have to trace the actual path from origin to destination.

• Just the start and end of the travel is recorded as corresponding columns and row.

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Multiple activity chart

• A chart on which the activities of more than one subject (worker, machine, equipment) are each recorded on a common time scale to show their interrelationship.

• By using separate vertical columns, or bars to represent the activities of different operators or machines against a common time scale the chart shows the periods of idleness on the part of any subjects, during the process.

• This makes it possible to rearrange these activities so that such ineffective time is reduced.

• Extremely useful in organizing teams of operatives on mass-production work, also on maintenance work when scheduling expensive plant.

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Why charts?

• It gives a complete picture of what is being done and helps to understand the facts and its relationship to one another.

• Details on the chart must be obtained from direct observation. Should not be from memory.

• Neatness and accuracy important.• Increased value if following is included: 1. Product, equipment details (code#, drawing#)2. Job or process being carried out3. Location and time (date) of the study4. Observer’s name5. Chart reference number

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Examine critically

• Means by which each activity is subjected to a systematic and progressive series of questions.

• Grouping of activities: Five sets of activities can be grouped in two categories

• Those in which something actually happens to the work-piece (it is moved, worked upon or examined)

• Those in which it is not being touched (in storage or in delay)

• Objective is to maximize proportion of “do” activities.

• All other activities, however necessary, are considered “non-productive.”

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Primary questions

• The PURPOSE for which

• The PLACE at which

• The SEQUENCE in which

• The PERSON by whom

• The MEANS by which

……………………….…………the activities are undertaken.

With a view to ELIMINATING, COMBINING, REARRANGING, or SIMPLIFYING those activities.

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Primary questions

PURPOSEWhat?

Why?ELIMINATE unnecessary part of the job

PLACE Where?

COMBINE wherever possible or REARRANGE the sequence for better result

SEQUENCE When?

PERSON Who?

MEANS How? SIMPLIFY the operation

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The secondary questions

PURPOSEWhat else might be done?

What should be done?

PLACEWhere else might be done?

Where should be done?

SEQUENCEWhen else might be done?

When should be done?

PERSONWho else might be done?

Who should be done?

MEANSHow else might be done?

How should be done?

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Classification of TherbligsEffective therbligs:• Transport empty• Grasp• Transport loaded• Release load• Use• Assemble• Disassemble• Inspect• Rest

Ineffective therbligs:• Hold• Pre-position• Position• Search• Select• Plan• Unavoidable delay• Avoidable delay

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Micromotion Analysis• Each therblig represents time and energy spent by a worker to

perform a task. If the task is repetitive, of relatively short duration, and will be performed many times, it may be appropriate to analyze the therbligs that make up the work cycle as part of the work design process.

• The term micromotion analysis is sometimes used for this type of analysis.

• Objectives:1. Eliminate ineffective therbligs if possible2. Avoid holding objects with hand – Use workholder3. Combine therbligs – Perform right-hand and left-hand motions

simultaneously4. Simplify overall method5. Reduce time for a motion, e.g., shorten distance

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Principles of Motion Economy

• Developed over many years of practical experience in work design

• They are guidelines that can be used to help determine • Work method• Workplace layout• Tools, and equipment

• Objective is to maximize efficiency and minimize worker fatigue

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Three Categories of Principles

The principles of motion economy can be organized into three categories:

1. Principles that apply to the use of the human body

2. Principles that apply to the workplace arrangement

3. Principles that apply to the design of tooling and equipment

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Use of Human Body1. Both hands should be fully utilized.

• The natural tendency of most people is to use their preferred hand (right hand for right-handed people and left hand for left-handed people) to accomplish most of the work.

• The other hand is relegated to a minor role, such as holding the object, while the preferred hand works on it. This first principle states that both hands should be used as equally as possible.

2. The two hands should begin and end their motions at the same time.

• This principle follows from the first. To implement, it is sometimes necessary to design the method so that the work is evenly divided between the right-hand side and the left-hand side of the workplace. In this case, the division of work should be organized according to the following principle.

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3. The motions of the hands and arms should be symmetrical and simultaneous.

• This will minimize the amount of hand-eye coordination required by the worker. And since both hands are doing the same movements at the same time, less concentration will be required than if the two hands had to perform different and independent motions.

4. The work should be designed to emphasize the worker’s preferred hand.

• The preferred hand is faster, stronger, and more practical. If the work to be done cannot be allocated evenly between the two hands, then the method should take advantage of the worker’s best hand.

• For example, work units should enter the workplace on the side of the worker’s preferred hand and exit the workplace on the opposite side. The reason is that greater hand-eye coordination is required to initially acquire the work unit, so the worker should use the preferred hand for this element. Releasing the work unit at the end of the cycle requires less coordination.

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5. The worker’s two hands should never be idle at the same time.

• The work method should be designed to avoid periods when neither hand is working. It may not be possible to completely balance the workload between the right and left hands, but it should be possible to avoid having both hands idle at the same time.

• The exception to this principle is during rest breaks. The work cycle of a worker-machine system may also be an exception, if the worker is responsible for monitoring the machine during its automatic cycle, and monitoring involves using the worker’s cognitive senses rather than the hands. If machine monitoring is not required, then internal work elements should be assigned to the worker during the automatic cycle.

• The next five principles of motion economy attempt to utilize the laws of physics to assist in the use of the hands and arms

while working.

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6. Method should consist of smooth continuous curved motions rather than straight motions with

sudden changes in direction

• It takes less time to move through a sequence of smooth continuous curved paths than through a sequence of straight paths that are opposite in direction, even though the actual total distance of the curved paths may be longer (since the shortest distance between two points is a straight line).

• The reason behind this principle is that the straight-line path sequence includes start and stop actions (accelerations and decelerations) that consume the worker’s time and energy.

• Motions consisting of smooth continuous curves minimize the lost time in starts and stops.

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7. Use momentum to facilitate task

• When carpenters strike a nail with a hammer, they are using momentum, which can be defined as mass times velocity. Imagine trying to apply a static force to press the nail into the wood.

• Not all work situations provide an opportunity to use momentum as a carpenter uses a hammer, but if the opportunity is present, use it. The previous principle dealing with smooth continuous curved motions illustrates a beneficial use of momentum to make a task easier.

8. Take advantage of gravity – Don’t oppose it

• Less time and energy are required to move a heavy object from a higher elevation to a lower elevation than to move the object upward. The principle is usually implemented by proper layout and arrangement of the workplace, and so it is often associated with the workplace arrangement principles of motion economy.

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9. Method should achieve a natural cadence of the motions involved

• Rhythm refers to motions that have a regular recurrence and flow from one to the next. Basically, the worker learns the rhythm and performs the motions without thinking, much like the natural and instinctive motion pattern that occurs in walking.

10. Use lowest classification of hand and arm motion (five classifications)

• The five classifications of hand and arm motions are presented in Table 10.5.

• With each lower classification, the worker can perform the hand and arm motion more quickly and with less effort. Therefore, the work method should be composed of motions at the lowest classification level possible.

• This can often be accomplished by locating parts and tools as close together as possible in the workplace.

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The two remaining human body principles of motion economy are recommendations for using body members other than the hands and arms.

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11. Minimize eye focus and travel• In work situations where hand-eye coordination is required, the eyes

are used to direct the actions of the hands. Eye focus occurs when the eye must adjust to a change in viewing distance—for example, from 25 in. to 10 in. with little or no change in line of sight.

12. The method should be designed to utilize the worker’s feet and legs when appropriate.

• The legs are stronger than the arms, although the feet are not as practical as the hands. The work method can sometimes be designed to take advantage of the greater strength of the legs, for example, in lifting tasks.

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Workplace Arrangement• Figure 10.2 Normal and maximum working

areas in the workplace.

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1. Locate tools and materials in fixed positions within the work areaAs the saying goes, “a place for everything, and everything in its place.” The worker eventually learns the fixed locations, allowing him to reach for the object without wasting time looking and searching.

2. Locate tools and materials close to where they are usedThis helps to minimize the distances the worker must move (travel empty and travel loaded) in the workplace. In addition, any equipment controls should also be located in close proximity.

3. Locate tools and materials to be consistent with sequence of work elements: Items should be arranged in a logical pattern that matches the sequence of work elements. Those items that are used first in the cycle should be on one side of the work area, the items used next should be next to the first, and so on,.

4. Use gravity feed bins to deliver small parts and fasteners

5. Use gravity drop chutes (channels, tubes) for completed work units where appropriate

6. Provide adequate illumination

Workplace Arrangement

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Illustration of First Three Principles

Two workplace layouts.

(a) Poor arrangement of parts and tools in workplace

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Illustration of First Three Principles(b) Good arrangement of parts and tools in

workplace Numbers indicate sequence of work elements in relation to locations of hand

tools and parts bins.

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Design of Tooling and Equipment

1. Work-holding devices should be designed for the task; A mechanical work holder with a fast-acting clamp permits the work unit to be loaded quickly and frees both hands to work on the task productively.

2. Hands should be relieved of work elements that can be performed by the feet using foot pedals; Foot pedal controls can be provided instead of hand controls to operate certain types of equipment. Sewing machines are examples in which foot pedals are used as integral components in the operation of the equipment.

3. Combine multiple functions into one tool where possible; such as head of a claw hammer is designed for both striking and pulling nails.

4. Perform multiple operations simultaneously rather than sequentially; A work cycle is usually conceptualized as a sequence of work elements or steps

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5. Where feasible, perform operation on multiple parts simultaneously; This usually applies to cases involving the use of a powered tool such as a machine tool. A good example is the drilling of holes in a printed circuit board (PCB). The PCBs are stacked three or four thick, and a numerically controlled drill press drills each hole through the entire stack in one feed motion.

6. Design equipment controls for operator convenience and error avoidance; Equipment controls include dials, cranks, levers, switches, push buttons, and other devices that regulate the operation of the equipment. All of the controls needed by the operator should be located within easy reach, so as to minimize the body motions required to access and activate them.

7. Hand tools and portable power tools should be designed for operator comfort & convenience; For example, the tools should have handles or grips that are slightly compressible so that they can be held and used comfortably for the duration of the shift

8. Mechanize or automate manual operations if economically and technically feasible

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Facility layout - Procedure

• Start with the flow diagram/model.

• Map all the material movements on the flow diagram/model.

• Measure distances of travel (computer output, thread method, drawing lines on the diagram etc.)

• Analyze the current practice using a flow chart.

• Go through the usual rounds of primary and secondary questions.

• Develop the improved method.

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Material handling

• Typically material handing may take up to 85% of the total process time.

• Only important method study principle: Motion Economy!• Material handling adds to the cost of manufacture but adds

nothing to the value of the product.• Therefore, ideally there should be no material handling.• Typical material handling problem solved in the same way as

all method study problem – start with asking questions.

• Most important question: WHY is this handling done?

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Material handling: Process

• Traditional way of solving any method study problems

• Use of outline and process flow charts and flow diagrams to ensure a correct workplace layout.

• AIM: Minimization of movement in any plane – horizontal or vertical.

• Specially critical when one is buying material handling equipment for the workplace.

• Change in workplace layout affects not only the quantity but also the type of material handling equipment necessary.

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Material handling: Important aspects

• Always try to keep material at the height at which they are to be worked upon.

• Never keep material on floor.• Always keep distances over which material is handled as short

as possible.• Let gravity work for you.• Always handle in bulk over distances.• Always have sufficient boxes, platforms or container available

at the workplace.• Keep gangways clear.• Don’t reduce the supplementary human labor if it means

increase in the load for direct operators.

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Effects of shop layout on worker movement

There are many activities in which workers move at irregular intervals between a number of points in the working area, with or without material. This happens when,

• Bulk material is fed to or removed from a continuous process.

• An operator is looking after two or more machines.

• Laborers are delivering material to or removing work from a series of machines.

• In stores and shops when variety of materials are being removed from or put away into racks or bins.

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Making the Time Study

1. Secure and record information about the operation and operator being studied.

2. Divide the operation into elements and record a complete description of the method.

3. Observe and record the time taken by the operator.

4. Determine the number of cycles to be timed.

5. Rate the operator’s performance.

6. Check to make certain that a sufficient number of cycles have been timed.

7. Determine the allowances.

8. Determine the time standard for the operation.

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Reasons for Element Breakdown

1. One of the best ways to describe an operation is to break it down into definite and measurable elements and describe each of these separately.

2. Standard time values may be determined for the elements of the job. Such element time standards make it possible to determine the total standard time for an operation.

3. A time study may show that excessive time is being taken to perform certain elements of the job.

4. An operator may not work at the same tempo throughout the cycle. A time study permits separate performance ratings to be applied to each element.

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Rules for Element Breakdown

• All manual work may be divided into therbligs which are too short in duration to be timed with a stop watch. A number of them must be grouped together into elements of sufficient length.

– The elements should be as short in duration as can be accurately timed.

– Handling time should be separated from machine time.

– Constant elements should be separated from variable elements.

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Time study equipment

– a stop-watch– a study board– time study forms

Stopwatch Time Study

• Stopwatch time study is the most common technique for setting time standards in the manufacturing area.

• The time standard is the most important piece of manufacturing information, and stopwatch time study is often the only method acceptable to both management and labor.

• Stopwatch time study was developed by Frederick W. Taylor in 1880 and was the first technique used to set engineered time standards.

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TOOLS OF STOPWATCH TIME STUDY

• The tools of stopwatch time study are important to know before we get into the technique itself.

1. Stopwatches

a. Continuousb. Snapbackc. Three-watchd. Methods time measuremente. Digital f. Computer

2. Boards for holding watches and paper

3. Videotape recorders

4. Forms

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Time study forms

• Taking a time study requires the recording of substantial amounts of data. These data are in a regular form consisting of element codes or descriptions, ratings and element durations.

• It is more convenient to use pre-printed forms which ensure that each study is of the same consistent format, that all relevant data are recorded more reliably.

• There are numerous designs of forms; most work study practitioners have their own ideas on the ideal layout.

• The principal forms used in time study fall into two groups:

• Those used at the point of observation while actually making the study, and those which are used after the study, as part of the analysis process, in the study office.

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Forms used on the study board

Time study top sheet:

• The top and introductory sheet of a study, on which is recorded all the essential information about the study, the elements into which the operation being studied has been broken down, and the breakpoints used. It may also record the first few cycles of the study itself.

• The sketch of the workplace layout, which should be drawn either on the reverse of the sheet, if the layout is very simple, or on a separate sheet (preferably of squared paper) and attached to the study.

Continuation sheet:

• This form is used for further cycles of the study. An example is shown in figure 100. These two forms are the ones most generally used. Together they are adequate for most general time study work.

• For the recording of short cycle repetitive operations, however, it is convenient to use a specially ruled form instead.

Short cycle study form:

• Two examples of a short cycle form are illustrated. That in figure 101 shows a simple type of form which serves very well for most common short cycle work.

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Forms used in the study office

Working sheet for analyzing the readings obtained during the study and obtaining representative times for each element of the operation.

Study summary sheet to which the selected times for all the elements are transferred, with the frequencies of the elements’ occurrence.

• This sheet, as its name suggests, summarizes neatly all the information which has been obtained during the course of the study. An example is in figure 104.

Analysis of studies sheet on which are recorded, from the study summary sheets, the results obtained in all the studies made on an operation. It is from the analysis of studies sheets that the basic times for the elements of the operation are finally compiled.

Specially ruled sheet is for the compilation of relaxation allowances.

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An Example

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An other Example

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average

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Selected time

Variable element• In general more observations will be necessary of a variable

element than of a constant element before reliable representative basic times can be established.

• The analysis of factors affecting the time to complete the element should be closely studied.

• Some relationship should be established between the observed time and the variable factors.

• Multiple factors could be affecting the observed time variation and establishing relationships amongst multiple factors is difficult

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Work content

• The work content of a job or operation is defined as: basic time+ relaxation allowance+ any allowance for additional work (e.g. the part of relaxation allowance that is work related).

• Standard time is the total time in which a job should be completed at standard performance – i.e. work content, contingency allowance for delay, unoccupied time and interference allowance.

• Allowance for unoccupied time and interference may not be frequently included in the standard time calculations; however, the relaxation allowance is.

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Standard time constituents

• A contingency allowance is a small allowance of time which may be included in a standard time to meet legitimate and expected items of work or delays, precise measurement of which is uneconomical because of their infrequent or irregular occurrence.

• Contingency allowance for work should include fatigue allowance; whereas the allowance for delay should be dependent on the workers.

• Typically contingency allowances are very small and are generally expressed as percentage of the total repetitive minutes of the job.

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• Contingency allowance should not be more than 5%, and should only be given where the contingencies cannot be eliminated and are justified.

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• Relaxation allowance is an addition to the basic time intended to provide the worker with the opportunity to recover from the physiological and psychological effects of carrying out specified work under specified conditions and to allow attention to personal needs.

• The amount of the allowance will depend on the nature of the job.

• One of the major additions to the basic time.• Industrial fatigue allowance, in turn, forms a major portion of

the relaxation allowance.• Relaxation allowances are also given as percentages of the

basic times.

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• Typical values of relaxation allowance are 12-20%.

• In addition to including relaxation allowances, short rest pauses could be added over the period of work for an operator.

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Other allowances

• Start-up / shut-down allowance

• Cleaning allowance

• Tooling allowance

• Set-up / change-over allowance

• Reject / excess production allowance

• Learning / training allowance

• Policy allowance is an increment, other than the bonus increment, applied to standard time to provide a satisfactory level of earning for certain level of performances under exceptional conditions.

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Standard time

• Now, we can add all the constituents to arrive at the standard time for a job.

Standard time = observed time + rating factor + relaxation allowance + work related contingency allowance + delay related contingency allowance.

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Work sampling is a method of finding the percentage occurrence of a certain activity by statistical sampling and random observations.

• Work sampling, or activity analysis, is the process of making sufficient random observations of an operator’s activities to determine the relative amount of time the operator spends on the various activities associated with the job.

The major goal of work sampling is to determine how long, or how much of the work day, is spent on specific types of work.

• Work sampling may identify the fact that certain operators spend a large portion of their time waiting for work, or performing paperwork tasks, or even performing activities that are not included in their job descriptions.

• One of the basic foundations of statistical sampling theory is the concept that the larger the sample size, the results will be better or more accurate.

• In work sampling, a sufficient number of observations must be made to be sure that the results accurately summarize the work performed. There are statistical formulas to help determine how many observations should be made.

• The number of observations that an analyst must make of a particular job also depends on how much time is devoted to a particular task.

Work Sampling

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CONDUCTING A WORK SAMPLING STUDY• It is recommended that a uniform procedure should be followed to perform a

work sampling study is to

1. Establish the Purpose• First, the objective of the study should be established. Work sampling can be

used to determine an overall perspective on the work done.

2. Identify the Subjects• Second, the people performing the task must be identified, i.e. general office

work is being studied with the objective of determining overall productivity.

3. Identify the Measure of Output• The third step in making the study is the identification of the measure of the

output produced or the types of activities performed on the jobs being studied. This step is especially important if the objective of the study is to measure productivity with the intent of setting a standard.

4. Establish a Time Period• Fourth, the time period during which the study will be conducted must be

established. Starting and stopping points for the study must be defined as well.

5. Define the Activities• This step involves defining the activities that are performed by the people

under study. For example, the definition used in a machine utilization study, including only the categories of working, idle, and idle-mechanical breakdown.

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6. Determine the Number of Observations Needed

• After the work elements are defined, the number of observations for the desired accuracy at the desired confidence level must be determined. The sample size is dependent on the percentage of time believed to be spent on the major work element.

• If a reasonable guess cannot be made, then a trial study of perhaps 20 to 40 observations should be made to get an estimate of this portion. These initial observations should be included with the rest of the observations taken during the rest of the work study.

7. Schedule the Observations

• Once the number of required observations has been determined, either from appropriate statistical calculations or from tables, the actual observations must be scheduled. Typically, the analyst will assign an equal number of observations each day during the course of the study.

• For example, if 800 observations are required and 20 work days are established as an appropriate observation time, 40 observations should be recorded each day.

• A random number table can be used to establish the random times for each observation.

8. Inform the Personnel Involved

• Before the study is actually performed, the personnel involved should be informed about the objective of the study and the methodology that will be employed. As in any productivity measurement study, this part of the procedure is very important.

• Workers and their supervisors might think that they personally are being measured rather than the work they are doing.

9. Record the Raw Data

• The next and perhaps the easiest part of any work sampling study is the actual recording of the raw data. Although this recording can be performed by anyone, it is desirable that a trained analyst be employed.

• It is also very important that the observations be made at exactly the same location every time. Failure to be reliable in this manner may bias the results.

10. Summarize the Data• After the data have been collected, they must be summarized.

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A few words about sampling• Sampling is mainly based on probability. Probability has been defined

as “the degree to which an event is likely to occur”.

• A simple and often-mentioned example that illustrates the point is that of tossing a coin.

• The law of probability says that we are likely to have 50 heads and 50 tails in every 100 tosses of the coin. The greater the number of tosses, the more chance we have of arriving at a ratio of 50 heads to 50 tails.

• The size of the sample is therefore important, and we can express our confidence in whether or not the sample is representative by using a certain confidence level.

Establishing confidence levels• Let us go back to our previous example and toss five coins at a time,

and then record the number of times we have heads and the number of times we have tails for each toss of these five coins. Let us then repeat this operation 100 times.

• If we considerably increase the number of tosses and in each case toss a large number of coins at a time, we can obtain a smoother curve, such as that shown in figure 89.

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• To make things easier, it is more convenient to speak of a 95 per cent confidence level than of a 95.45 per cent confidence level.

• To achieve this we can change our calculations and obtain:

– 95 per cent confidence level or 95 per cent of the area under the curve = 1.96– 99 per cent confidence level or 99 per cent of the area under the curve = 2.58– 99.9 per cent confidence level or 99.9 per cent of the area under the curve = 3.3

• In this case we can say that if we take a large sample at random we can be confident that in 95 per cent of the cases our observations will fall within ± 1.96

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Determination of sample size

• As well as defining the confidence level for our observations we have to decide on the margin of error that we can allow for these observations.

• Let us look at our example about the productive time and the idle time of the machines in a factory. There are two methods of determining the sample size that would be appropriate for this example:

• the statistical method and the nomogram method.

Statistical method. The formula used in this method is:

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• Let us assume that some 100 observations were carried out as a preliminary study and at random, and that these showed the machine to be idle in 25 per cent of the cases (p = 25) and to be working 75 per cent of the time (q = 75).

• We thus have approximate values for p and q; in order now to determine the value of n, we must find out the value of .

• Let us choose a confidence level of 95 per cent with a 10 per cent margin of error (that is, we are confident that in 95 per cent of the cases our estimates will be ± 10 per cent of the real value).

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Nomogram methodAn easier way to determine sample size is to read off the number of observations needed directly from a nomogram such as the one reproduced in figure 91.

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Making random observations

• To ensure that our observations are in fact made at random, we can use a random table such as the one in table 12.

• Various types of random table exist, and these can be used in different ways. In our case let us assume that we shall carry out our observations during a day shift of eight hours, from 7 a.m. to 3 p.m. An eight-hour day has 480 minutes. These may be divided into 48 ten-minute periods.

• We can start by choosing any number at random from our table, for example by closing our eyes and placing a pencil point somewhere on the table. Let us assume that in this case we pick, by simple chance, the number 11 which is in the second block, fourth column, fourth row (table 12).

• We now choose any number between 1 and 10. Assume that we choose the number 2; we now go down the column picking out every second reading and noting it down, as shown below (if we had chosen the number 3, we should pick out every third figure, and so on).

• 11 38 45 87 68 20 11 26 49 05

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• Looking at these numbers, we find that we have to discard 87, 68 and 49 because they are too high (since we have only 48 ten-minute periods, any number above 48 has to be discarded).

• Similarly, the second 11 will also have to be discarded since it is a number that has already been picked out. We therefore have to continue with our readings to replace the four numbers we have discarded. Using the same method, that is choosing every second number after the last one (05), we now have14 15 47 22

• These four numbers are within the desired range and have not appeared before. Our final selection may now be arranged numerically and the times of observation throughout the eight-hour day worked out. Thus our smallest number (05) represents the fifth ten-minute period after the work began at 7 a.m. Thus our first observation will be at 7.50 a.m., and so on (table 13).

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Example: Conducting the study• Determining the scope of the study. Before making our actual observations, it is

important that we decide on the objective of our work sampling. • The simplest objective is that of determining whether a given machine is idle or

working. • In such a case, our observations aim at detecting one of two possibilities only:

• We can, however, extend this simple model to try to find out the cause of the stoppage of the machine:

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Making the observations

• So far we have taken the first five logical steps in conducting a work sampling study.

– selecting the job to be studied and determining the objectives of the study;

– making a preliminary observation to determine the approximate values of p and q;

– in terms of a chosen confidence level and accuracy range, determining n (the number of observations needed) determining the frequency of observations, using random tables;

– designing record sheets to meet the objectives of the study.

– There is one more step to take: that of making and recording the observations and analyzing the results.

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Group sampling techniques• As the name suggests, these are designed for the measurement of

work carried out by groups of workers.

• The techniques are sometimes referred to by the term “high-frequency sampling” since, when used for the measurement of short-cycle work, they use fixed short-time intervals with the observer in constant attendance.

• They are very close to time study but have the advantage that the observer can cover the work of the group. Group sampling techniques may make use of rating.

• Consider a very simple example of three workers each producing the same parts by a process that involves only hand tools. The sampling is carried out at 0.5 minute intervals and involves the categories of “working” and “not working” only.

• The sampling observations have been rated and this is an example of both rated activity sampling and group sampling.

• The sampling sheet would look as shown in table 14.

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Predetermined Motion Time Systems

• Predetermined motion time system (PMTS) is a work measurement technique whereby times established for basic human motions are used to build up the time for a job at a defined level of performance.

• PMTS also called predetermined time system (PTS), is a database of basic motion elements and their associated normal time values, together with a set of procedures for applying the data to analyze manual tasks and establish standard times for the tasks.

• The PMTS database is most readily conceptualized as a set of tables listing time values that correspond to the basic motion elements, the lowest level in our hierarchy of manual work activity

• They include motions such as reach, grasp, move, and release.

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The Predetermined Motion Time Systems Concept

Likewise, a job is also considered to consist of elements, the

total of which is the sum of the elements.

In formal words, the assumption is that each job element is

independent and additive; that is, each element does not affect

what happens before or after it - independence and additivity.

The concept is similar to constructing a building. A building is

composed of elements-Doors, walls, beams, bricks, plumbing.

The structure is the sum of the elements.

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What are Predetermined Motion Time Systems?

A collection of basic motion times.

Technique for obtaining a standard time by:

Analyzing and subdividing a task into elemental

motions

Assigning pre-set standard times for motions and

summing these to obtain a standard time for the whole

task.

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Popular Predetermined Motion Time Systems

Methods -Time Measurement

Work-Factor

Predetermined Time Standards

Systems – Meyers

MOST

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Methods Time Measurement (MTM)

MTM is a procedure which analyzes any manual

operation or method into the basic motions required to

perform it, and assigns to each motion a

predetermined time standard which is determined by

the nature of the motion and the conditions under

which it is made.

MTM gives values for the fundamental motions of:

reach, move, turn, grasp, position, disengage, and

release.

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Methods Time Measurement (MTM)

Most predetermined motion time systems use

time measurement units (TMU) instead of

seconds for measuring time. One TMU is defined

to be 0.00001 hours, or 0.036 seconds. These

smaller units allow for more accurate

calculations without the use of decimals. 1 hr =

100,000 TMU

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MTM studies provided the following kinds of information

Developing effective work methods prior to production

Improving existing methods to increase production and

decrease labor cost per unit

Establishing time standards as basis for wages and incentive

plans

Developing time formulas or standard data for future use

Guiding product design for most efficient manufacture

Developing effective tool designs for most efficient

manufacture

Selecting effective equipment for most efficient manufacture

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Advantages of PMTS systemsPMT systems offer a number of advantages over stop-

watch time study. With PMT systems one time is indicated for a given motion, irrespective of where such a motion is performed.

A PMT system, which avoids both rating and direct observation, can lead to more reliability in setting standard times.

PMT systems are not too difficult to apply and can be less time consuming than other methods.

PMT systems are particularly useful for very short repetitive time cycles such as assembly work in the electronics industry.

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PMTS Levels and GenerationsChronologically, first-level PMT systems were the

first to be developed, and then second - and higher - level systems were subsequently constructed based on the first-level systems.

• Because of this chronological development of the systems, the level of the system usually corresponds to the generation of the system.

• First-level PMT systems are called first generation systems, and the subsequent systems are second and third generations.

• For example, MTM-1 is first generation MTM-2 is second generation and is based on MTM-1. MTM-3 is a third generation MTM system.

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Characteristics of PMT system levels

Work Systems and the Methods, Measurement, and Management of Workby Mikell P. Groover, ISBN 0-13-140650-7.©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

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MTM-1• In our hierarchy of work activity, MTM-1 operates at the

basic motion element level, as illustrated in Figure 14.1.

• Most of the MTM-1 basic motions involve hand and arm movements, although elements are also provided for eye, leg, foot, and body actions.

• MTM was developed by studying motion pictures of work activity, and the time units for MTM were originally defined as the time per frame of motion picture film, and defined as

• 1 TMU = 0.00001 hr = 0.0006 min = 0.036 sec• 100,000 TMUs in 1 hour, • 1667 TMUs in 1 min, and • 27.8 TMUs in 1 sec.

• Table 14.3 defines the MTM-1 motion elements, and Table 14.4 presents a tabulation of their time values.

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Figure 14.1 The position of MTM motion elements in our work hierarchy.

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Other MTM Systems

• Other members of the MTM family satisfy various user needs.

• MTM-2 – Second-level PMTS in which basic motion elements are combined into motion aggregates

– GET – combines Reach and Grasp– PUT – combines Move and Position

• MTM-3 – Third-level PMTS which has four motion categories1. Handle2. Transport3. Step and foot motions4. Bend and arise

• Table 14.5 lists many of these MTM systems with a brief description of each.

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