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Work study

5W – 1H on work study

What is work-study? – A productivity

improvement tool of Industrial Engg., a function

whose responsibility is to make

processes efficient

manufacturing easy

quality better

It deals with various aspects of productivity

improvement like :

Workplace layout

Standards

Ergonomics etc

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Where is this done? – At any place of work

where value adding activity is carried out

When is work-study done?–Q C D parameters

are poor

Who does work-study? Trained work study

expert

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Why is this done? – The objectives

1. Productivity improvement : Better utilization

of resources

2. Achievement of QCD objectives

3. To expose weak areas in management

4. To identify training needs

5. To establish industrial engineering standards

6. Planning

7. Formulation of Incentive Schemes

How is this done?

• Work study is made up of method study and

work measurement

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Method study

•Method study deals with studying method of

doing the work for identifying and eliminating non

value activities

• Work that is carried out comprises of various

activities which add only cost and no value

• Method study removes the NVAs [non value

activities] by design which makes the productivity

go up

Work measurement

Work measurement leads toProductivity Improvement

Industrial Engineering standards

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20% of Total Time

A

B

C

D

Basic Work Content of Product and or Operation

Work Content added by defects in design or specification of product

Work Content added by inefficient methods of Manufacture or Operation

Ineffective Time due to shortcomings of Management

Ineffective Time within the control of worker

1.Total work content

2.Total ineffective time

1+2 = Total Time of Operation under existing conditions

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Basic work content

Only 20% of total time

Irreducible work content

Any reduction compromises quality

Determined by technology

Work content added by management

A: Bad design of the product

• Door handle on refrigerator

Bad specifications

• Glass wool as insulator

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B: Inefficient process of manufacture

• Using blunt tool for cutting

• Excessive material handling

• Using non standard inputs

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Ineffective time added by management

Bad working conditions

Muri in work, bad ergonomics, bad layout

Accidents due to lack of training

Lack of training

Ineffective time added by workers

Rework of defects due to poor skill

Accidents due to

• Carelessness

• Lack of awareness

Fatigue

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Work measurementActivity sampling

Time studyPMTSMOST

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Following are eight steps of work study in which

method study and work measurement activities

complement each other

1. Select [M/S & W/M]

• Human angle

• Technological angle

• Economical angle

• Management needs

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MICROMOTION STUDY THERBLIG ANALYSIS -

PROCESS MAPPING

STRING DIAGRAM

VEDEO SHOOTING OR FILMING

2. Record –recording techniques

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3. Examine [M/S] - ask primary & secondary

questions

4. Develop [M/S] – Alternatives to current method

using principles of ergonomics &

motion economy

• Use of human body

• Arrangement of the work place

• Design of tools and equipment

• Compatibility between man & his work

environment

• Reducing fatigue, mental & physical

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TIME STUDY

ACTIVITY SAMPLING

ANALYTICAL ESTIMATION

PREDETERMINED TIME STANDARDS [PMTS]

SYNTHESIS

5. Measure [W/M]

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6. Define [M/S & W/M]

• Define the new method and time standards

7. Install [M/S]

• Implementation of new method

8. Maintain [M/S]

• Critical Phase as habits die hard Principals used

in developing new method are shown in the next

slide in dotted lines

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Work measurement

• Time Study

• Activity Sampling [snap reading]

• Analytical Estimation

• Predetermined Time Standards [PMTS]

• Synthesis

• MOST [Maynard Operating Sequence

Technique]

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Concepts in Time Study

Element: An element is a distinct part of a

specified job selected for convenience of

measurement and analysis

Work cycle: A work cycle is a sequence of

elements which are required to perform a job or

yield a unit of production

Qualified worker: Qualified worker is one who

has the necessary physical attributes, intelligence

and education, skills and knowledge to carryout the

work in hand to satisfactory standards of safety,

quantity and quality

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Standard Performance: is the rate of output

qualified workers would naturally achieve

without over exertion as an average over the

working day or shift, provided they adhere to

the specified method and they are motivated to

apply themselves to work

Rating: Relative assessment of a worker whose

performance is under observation by

comparing to the performance of a qualified

worker

Standard Time: Time needed by a qualified

worker to completely perform a job under

normal working conditions

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Allowances: Additional time added to the

normal time to enable employees to

Attend to their personal needs (Relaxation

Allowance)

Run more than one machine (Interference

Allowance)

Overcome unexpected and unavoidable delays

Increase their earnings (Policy Allowance)

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Observations: Observing the worker

performing an element of the job with his or her

full knowledge with the intention of recording the

time required for performance (when observations

are made as a part of time study)

Observed time: time recorded for performance

of an element by a worker under observation

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Basic time or Normalized time: The time

required by a qualified worker to perform the

element which is performed by the worker under

observation. When observed time is multiplied by

rating we get basic time or normalized time.

Suitability of Time Study

Time study is a statistical method

Time study is suitable for repetitive activities

which are found in a mass production system

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How time study is done?

Select the Job & worker : full knowledge of

the worker, active participation is necessary

Break the job into elements

Time each job element

Average out the time for each element

Rating – rate the worker

Deciding allowances

Compile standard time

Example ??

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Element No

Observed time in mins.

Performa--nce Rating

Allowance

1 5 120% 15%

2 6 110% 15%

3 4 120% 15%

4 5.5 80% 15%

5 5 80% 15%

Calculate Standard Time & Standard Output

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Eleme-nt No

Obser-ved time in mins

Perf. Ratin-g

Norm-alized time in mins

Allow-ance

Stand-ard time in mins

1 4 130% ? 15% ?

2 ? 80% 4.8 15% ?

3 4.5 ? 5.4 15% ?

4 ? 120% ? 15% 8

Fill in the blanks

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Activity Sampling [snap reading]

Also known as work sampling or snap reading

Used for determining resource utilization

A set of observations of the phenomenon are

made to find the presence or absence of the

desired parameter

Observations are analyzed to determine resource

utilization

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“It is a technique in which a large number of

instantaneous observations are made over a period

of time of a group of machines, processes or

workers. Each observation records what is

happening at that instant and the percentage of

observations recorded for a particular activity or

delay is a measure of the percentage of time

during which that activity or delay occurs”

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How do we calculate number of

observations?

E =K X √p(1-p)/N

E- tolerated inaccuracy of sample results (level of

inaccuracy), which is (1- confidence level in

decimal)

p-extent of the phenomenon being observed

(idleness)

N-number of observations

K=1, when S=68.27%, K=2, when S=95.45%

K=3, when S=99.73%

In a work sampling study, a mechanic was found to idle for 20% of the time. Find out the number of observations needed to confirm the above figures

with a confidence level of 95% and a relative error level by 5%

(Ref Ashwathappa for more numerical examples)

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Determining time standards by work sampling

Standard time for piece

= [(Total time in minuets X Working time

in %(from N observations) X performance index

in %)/(total number of pieces produced)] +

allowances

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Analytical Estimation

Work measurement is based on experience and

judgment

The job is split into bunch of elements and time

required is estimated applying ones experience

and judgment

Suitable for non repetitive activities carried out

infrequently like maintenance job or projects

“Analytical estimation is a work measurement

technique whereby the time required to carry out

elements of a job at defined level of performance

is estimated from knowledge and practical

experience of performing the elements concerned

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Predetermined Time Standards [PMTS]

Standards are developed and fixed for all basic

human activities by ILO after extensive research

in this area

These standards are used to develop standard

time for a job after splitting the job into a series

of human activities

PMTS is applied when micro-motion study of

job is done

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When micro-motion study is done?

“Predetermined Time Standards [PMTS] is a

work measurement technique whereby time

estimated for basic human motions (classified

according to the nature of the motion and the

conditions under which it is made) are used to

build up the time for a job at a defined level of

performance”

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Synthesis

Standards developed for other jobs are studied

From such jobs elements are located which are

common in the current job under study

Time standards of such elements are picked up

and used for developing time standard for current

job

“Synthesis is a work measurement technique for

building up the time for a job at a defined level of

performance by totaling element times obtained

previously from time studies on other jobs

containing the elements concerned, or from

synthetic data”

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