WORK ANALYSIS & WORK MEASUREMENT

TOTAL SLIDES: 75

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SYNOPSIS2

OBJECTIVE

Work study is concerned with finding better ways of doing work and avoiding waste in all its forms.

The objective has three aspects.

i. The most effective use of plant and equipment.

ii. The most effective use of human work.

iii.The evaluation of human work.

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Areas of work study

Work analysis Work measurement

Method study Time study

Motion study

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METHOD STUDY

Method study is the 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.

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OBJECTIVES OF METHOD STUDY

• Improvement of processes and procedures• Improvement in the design of plant and equipment• Improvement of layout• Improvement in the use of men, materials and machines• Economy in human effort and reduction of unnecessary

fatigue• Improvement in safety standards• Development of better working environment.

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When method study is conducted:

High operating costHeavy rejections Excessive movement of materials and menProduction bottle necksQuality problemsPoor working conditionsExcessive overtimePoor delivery performance

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ADVANTAGES OF METHOD STUDY

• Work simplification• Improved method (cheaper and productive)• Better quality product• Improved layout• Better material handling• Better work flow• Less fatigue to operator• Shorter production time• Job satisfaction

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BASIC PROCEDURE

Select

Record

Examine

Develop

Install

Maintain

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Selecting the work

There are three factors that should be kept in mind when selecting a job.

1. Economic or cost-effective considerations.2. Technical considerations.3. Human considerations.

1. Economic considerations: It is obviously a waste of time to start or continue a long

investigation if the economic importance of a job is small.

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A. Key profit-generating or costly operations or ones with the largest scrap/waste rates.

B. Bottlenecks which are holding up other production operations, or lengthy operations that consume a great deal of time.

C. Operations involving repetitive work using a great deal of labor and ones that are likely to run for a long time.

D. Movements of material over long distances between workstations, those involving the use of a relatively large proportion of labor or which require repeated handling of material.

Obvious choices for study11

One of the easiest techniques that could be used to identify key operations as listed in part (A) is the Pareto analysis (sometime also referred to as “the ABC analysis of value analysis”).

Pareto analysis12

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Selection cont…

2. Technical or technological considerations: One of the important considerations is the desire by

management to acquire more advanced technology, i.e. in equipment or in processes.

Therefore, management may want to computerize its office paperwork or its inventory system, or to introduce automation in the production operations.

Before such steps are taken, a method study could point out the most important needs of the enterprise in this respect.

The introduction of new technology should therefore constitute an important factor in the choice of methods of work to be investigated.

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Selection cont…

3. Human considerations:

Certain operations are often a cause of dissatisfaction by workers. They may bring on fatigue or monotony or may be unsafe to

operate. The level of satisfaction should point to a need for method study.

In a similar fashion, a choice of a particular job for study may lead to anxiety or ill feeling. The suggestion given here is to leave it alone.

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Record the facts

Record the facts

Record the facts

The next step in the basic procedure, after selecting the work to be studied, is to record all the facts relating to the existing method.

The success of the whole procedure depends on the accuracy with which the facts are recorded, because they will provide the basis of both the critical examination and the development of the improved method.

Recording serves essentially as a basis for following analysis and examination.

Recording may be carried out in two phases: First, a rough sketch or charting of the job being studied to

establish whether the recorded information is of use; Second, a more formal and accurate chart or diagram to include

in a report or presentation.

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Different recording techniques

TYPES RECORDING TECHNIQUES

INFORMATION RECORDED

CHARTS

Outline process chart Covers only main operations and Inspections

Operations process chart Includes operations, inspections and material inputs

Flow process charts Includes sequence of operations, transportation, inspections, delays and storages. For Material or product For Man For Machine

Two handed process charts Depicts the activities of both hands or limbsMultiple activity chart For more than one worker/ machine or

equipmentSIMO chart Simultaneous motion cycle chart . used for

Very small cycle time operations .

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Recording Techniques cont…

TYPES RECORDING TECHNIQUES

INFORMATION RECORDED

DIAGRAMS & MODELS

Flow diagram Actual paths followed by materials. Diagram drawn to scale

String diagram Sting used to trace the path of materials or workmen in a scale plan or a Model. To measure distances traveled.

PHOTOGRAPHIC AIDS

Cycle graph Movement of hand obtained by exposing a photographic plate to the light emitted from the small bulbs attached to the operator’s fingers

Chrono-cycle graphs Modification of cycle graph in which recording is made using flash lights

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OUTLINE PROCESS CHART

DIFFERENT ACTIVITIES

B1: Cutting the blade to required shape &size from a metal sheet.

B2: Making the hole located in triangular positions at the border end of the blade.

B3: Inspecting the exactness of the location of the holes using a template gauge with studs in the required triangular positions.

F1: Cutting the plate to required shape & size from a metal sheet.

F2: Making the 3 holes located in triangular positions at the right hand end of the plate which are used to fix the fixing plate on the blade.

F3: : Inspecting the exactness of the location of the holes using a template gauge with studs in the required triangular positions.

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ACTIVITIES CONT..

F4: Making two holes located on the left hand side of the fixing plate which are used to mount it on the motor housing.

F5:Inspecting the exactness of the locations of the two holes using a template gauge with studs in the required positions.

A1: position the fixing plate in the required location on the table.A2:insert three bolts each with a washer in to three hole passing

through fixing plate & the blade.A3:insert a washer on the other end of each of the three bolts.A4:Fix a nut on each of the three bolts & tighten it.A5:inpect the level of tightness.

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TWO HANDED PROCESS CHART

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Man machine chart 25

Examine

Examine critically: by using the questioning technique.

The questioning technique is the means by which the critical examination is conducted, each activity being subjected in turn to a systematic and progressive series of questions.

The questioning sequence used follows a well-established pattern which examines:

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Questioning techniques

Present facts Alternatives Action

Purpose What is being done?

What else could be done?

What should be done?

Method How is it being done?

How else could it be done?

How should it be done?

Sequence When is it being done?

When else could it be done?

When should it be done?

Place Where is it being done?

Where else could it be done?

Where should it be done?

Person Who is doing? Who else can do it?

Who should do it?

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DEFINING THE IMPROVED METHOD

The report should show: 1.     Relative costs in material, labour and overheads of the two methods, and savings expected.2. The cost of installing the new method, including the

cost of new equipment and of re-laying out shops or working areas

3.  Executive actions required to implement the new method.  

It should also give details regarding :1. The tools and equipment to be used2.      A description of the method3. A diagram of the work place layout, jigs/fixtures etc

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INSTALLING THE IMPROVED METHOD

1.  Gaining acceptance of the change by the Management

2.  Gaining acceptance of the change by the workers

3. Maintaining close contact with the progress of the job until

satisfied that it is running as intended

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MOTION STUDY

Analysis of basic hand, arm & body movements of worker as they perform their work.

Motion studies are performed to eliminate waste movements. Before any improvement in quality or quantity of output, any

study of operations time, any scheduling of work or balancing of workload or any calculation of standard time, a study of the current and proposed method is required.

Studies of overall factory flow or process is called macromotion studies, and additional studies of detail or operations is called micromotion studies,

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Motion studies

Macro motion

Micro motionMemo motion

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Micro motion studies

• Micro motion study was originated by Frank B. Gilbreth

• One of the most effective forms of work analysis available for job improvement.

• It is an analysis technique making use of motion pictures (or videotape) taken at a constant and known speed.

• The film becomes a permanent record of both the method being used and the time consumed in doing the work.

 

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MICROMOTION ANALYSIS

Micromotion analysis is analysis of Therbligs that make up a repetitive task

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.

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Objectives of micro motion analysis

A. Eliminate ineffective therbligs if possible

B. Avoid holding objects with hand – Use work holder

C. Combine therbligs – Perform right-hand and left-hand motions simultaneously

D. Simplify overall method

E. Reduce time for a motion, e.g., shorten distance

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Therbligs

• Frank Gilbreth – first to analyze and classify the basic motion elements

• Any work can be done by using a combination of 17 basic motions, called Therbligs.

Effective therbligs

TherbligsTherbligs

Ineffective

therbligs

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Classification of Therbligs

Effective 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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Effective & Ineffective therbligs

Effective therbligs are those that directly advance the progress of the work. These can sometimes be shortened but it is rarely the case that they cannot be eliminated.

Ineffective therbligs do not directly advance the progress of the work and should try to be eliminated or combined with another therblig to shorten the operation.

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Memomotion studies

 • Memomotion study was originated by M.E. Mundel.

• Special form of micromotion study in which the motion pictures or videotape are taken at slow speeds. (Sixty and one hundred frames per minutes are most common)

 

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Macro motion Study

Studies of overall factory flow or process is called macromotion studies.

Any process can be studied by dividing it into process activity.

Although each activity is different, depending on the product, there are five classes of activities that are included in all processes. Savings, may be found in the process by reorganizing activities.

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Process chart operators

OPERATOR OPERATION

point of origination

OOperation

Storage

Transportation

DDelay

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PROCESS CHART

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Improved process chart44

THE PRINCIPLES OF MOTION ECONOMY

Objective: maximize efficiency and minimize worker fatigue

Guidelines for work improvement Use of human body Arrangement of the work place Design of tools & equipment

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A. Use of Human Body

1. Design work to fully utilize both hands

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

3. Hand and arm motions should be symmetrical and simultaneous

4. Design work to favor preferred hand

5. Worker’s two hands should not be idle at the same School time

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

7. Use momentum to facilitate task

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

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Use of Human Body cont.

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

10. Minimize eye focus and travel

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

1) Finger

2) Finger and wrist

3) Finger, wrist, and forearm

4) Finger, wrist, forearm, and upper arm

5) Finger, wrist, forearm, upper arm, and shoulder

12. Design method to utilize feet and legs where appropriate

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 B. Arrangement of the work place

1. Definite and fixed stations should be provided for all tools and materials.

2. Gravity feed, bins and containers should be used to deliver the materials as close to the point of use as possible.

3. Tools, materials and controls should be located within the maximum working area.

4. Materials and tools should be arranged to permit the best sequence of motion.

5.  Provision should be made for adequate lighting.

6. The colour of the workplace should contrast with that of the workplace to reduce eye fatigue.

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 C. Design of tools and equipment

 

1.The hands should be relieved of all work of 'holding‘ the work piece where this could be done by fixture etc.

2.Two or more tools should be combined wherever possible

3.Levers, cross bars and hand wheels should be so placed that the operative could use them with the least change in body position and the greatest mechanical advantage.

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WORK MEASUREMENT

Work Measurement is the application of techniques

designed to establish time for a qualified worker to carry out a

specified job at a designed level of performance.

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techniques51

PURPOSE OF WORK MEASUREMENT

1 .To find ineffective time in a process

2. To set standard for output level

3.  To evaluate worker's performance

4.  To plan work force needs.

5. To determine available capacity

6.  To compare work methods

7.  To facilitate operations scheduling

8. To establish wage incentive scheme

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objective of Time and Motion Study

The objective of the Time Study is to determine a ‘normal’ or average time for a job, by using observers to record exactly how much time is being devoted to each task

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WHAT IS A TIME STANDARD

The definition of a time standard is “the time required to produce a product at a work station with the following three conditions:

(1) a qualified, well-trained operator,

(2) working at a normal pace,

(3) doing a specific task.”

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Procedure for stop-watch time study method

1. Establish the standard job method.2. Break down the job into elements (Elements may be repetitive, occasional, manual , machine foreign etc)3. Study the job.

4. Rate the worker’s performance

5. Compute the average time

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6. Compute the normal time

Nt =(t)(RF) or

Normal Time=(elemental average time) (rating factor)

7. Compute the standard time

ST=(Nt)(1+AF) or

StandardTime=(Normal cycle time)(1+Allowance factor)

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The normal time (NT) is the mean observed time multiplied by the performance rating factor (PRF)

The PRF is a subjective estimate of a worker’s pace relative to a normal work pace.

Rating factor= Observed performance / Normal performance

The allowance factor (AF) is the amount of time

allowed for personal, fatigue, and unavoidable delays

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Problem

There is a group of students stuffing envelopes. They have to put three different color-coded pages in the envelopes(red, white, orange).

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Operation Operation inserting the inserting the color pagecolor page

1 1 cyclecycle

2 cycle2 cycle 3 cycle3 cycle T T (min)(min)

RFRF NTNT

Color RedColor Red 0.020.02 0.060.06 0.030.03 0.0360.036 1.151.15 0.04140.0414

Color WhiteColor White 0.030.03 0.030.03 0.030.03 0.030.03 1.051.05 0.03150.0315

Color Color OrangeOrange

0.020.02 0.050.05 0.070.07 0.0460.046 1.001.00 0.0460.046

To compute the standard time :

Adjust the normal cycle with an allowance factor of 10 percent

ST= (NT)(1+AF)

= (.1189)(1+.10)

=.13079 min

To compute number of envelopes in one hour :

60 min/.13079min/envelope= 456 envelopes an hour

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Problem

to compute the no. of cyclesJim and Bob recently time-studied a janitorial task.

From a sample of 75 observations, they computed an average cycle time of 15 minutes with a standard deviation of 2 minutes. Was their sample large enough that one can be 99% confident that the standard time is within 5% of the true value?

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solution

• To find the number of samples required:

n = [( z*s) / ( e* T ) ]2

n = [ (2.576*2)/ (.05*15) ]2

= 47.15 or 48

 

 

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solution

Therefore, the sample size of 75 is sufficient.• To find coefficient of variance:

Coefficient of variance = (Standard deviation/ Mean) *100

= (2/15)*100

=13.33%

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Work Sampling

Determines the proportion of time a worker spends on activities

Primary uses of work sampling are to determine ratio delay

percentage of time a worker or machine is delayed or idle

analyze jobs that have non-repetitive tasksCheaper, easier approach to work measurement

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Work Sampling Procedure

Identify the worker or machine to be sampledDefine the activities to be observedEstimate the sample size based on level of accuracy and

confidence levelDevelop the random observation schedule. Make observations

over a time period that is representative of normal work conditionsObserve, record data, and check to see if the estimated sample size

remains validEstimate the proportion of the time spent on the given activity

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Steps of Work Sampling

1.1. Define job activitiesDefine job activities2.2. Determine number of observations in work sampleDetermine number of observations in work sample

n n = = pp(1 - (1 - pp) ) zzee

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wherewhere

nn = = sample size (number of sample sample size (number of sample observations)observations)zz = = number of standard deviations from mean number of standard deviations from mean for desired level of confidencefor desired level of confidenceee = = degree of allowable error in sample degree of allowable error in sample estimateestimatepp = = proportion of time spent on a work activity proportion of time spent on a work activity estimated prior to calculating work sampleestimated prior to calculating work sample

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Steps of Work Sampling (cont.)

3.3. Determine length of sampling periodDetermine length of sampling period

4.4. Conduct work sampling study; record Conduct work sampling study; record observationsobservations

5.5. Periodically re-compute number of observationsPeriodically re-compute number of observations

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Problem:

A work sampling study was made of a cargo loading operation for the purpose of developing its standard time. The study was conducted for duration of 1500 minutes during which, 1500 instantaneous observations were made at random intervals. The results of study indicated that the worker on the job was working 80 percent of the time and loaded 360 pieces of cargo during the study period. The work analyst rated the performance at 90 %. If the management wishes to permit a 13 % allowance for fatigue, delays and personal time, what is the standard time of this operation?

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Solution

Here, Total period = 1500 minutes

Working fraction = 80 percent

Average rating = 90 percent

Number of units loaded = 360

Allowances = 13 %

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Work sampling

Advantages • Economical• Not necessary to use trained work study experts• No stop watch measurements

  LimitationsLittle value to improve the operationsIf random sampling is not done results will be erroneous

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Synthesis method

Synthesis method takes values of normal time for each element from the data base developed and available.

Data base has elemental times for all similar job elements eg.loading, unloading, clamping, checking etc.

 

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Predetermined motion time systems

Times for basic motions ( Therbligs ) are established in TMUs ( time measurement units) .

1 TMU =0.036 sec. Times for reach, move , grasp etc are available in TMUs.

 

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Learning Curve

For repetitive work, worker gains skill, knowledge of product/process, etc over time

Thus we expect output to increase over time as more units are produced over time to complete task decreases as more units are produced

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Traditional Learning Curve75

Three approaches to learning curve

Arithmetic analysisLogarithmic analysisLearning curve tables

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Observations from learning curves

Average no. of labour hours required per unit for N units in a production run

Total no. of labour hours required to produce N units in a production run

The exact no. of labour hours required to produce the n th unit of a production run.

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Conclusion

Better design of plant equipment and buildings.Improved work flow.Improved utilization of resources.High earnings.Setting standards and rationalization.

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Thank you

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