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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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