Work Measurement

It is very useful to industry person as well as Diploma and Engineering Students

1. Industrial Engineering
TDME-505
Department of Mechanical Engineering


Presenting Topic
UNIT-02
“Work Measurement”
By

Prof. Anil Kumar Rao
Assistant Professor
Mechanical Engineering Department
Rabindranath Tagore University

2. OUTLINES
Work Measurement
Purpose of Work Measurement
Work Measurement Techniques
Basic Procedure to work measurement
Steps Involved in Work Measurement
Stop Watch Time Study
Procedure of Stop Watch Time Study
Types of Stop Watch Study
Element used in Time Study
Qualified Workers & Representative Workers
Job break down into elements

3. Work Cycle
Number of Work Cycle
Allowance
Performance Rating
Steps in Making Time Study
Computation of Standard Time
Components standard time
ILLUSTRATION-01
ILLUSTRATION-02
ILLUSTRATION-03

4. Definition: Work measurement can be defined as the implementation of a
series of techniques which are designed to find out the work content, of a
particular task or activity, by ascertaining the actual amount of time necessary
for a qualified worker, to perform the task, at a predetermined performance
level.
Work Measurement

5. Purpose of Work Measurement

6. Work Measurement Techniques
Image depicts different work measurement techniques, methods or
types.

7. Work measurement techniques are listed below:
•Historical data method - It uses the past performance data to set
performance standards.
•Time study - It uses stop watch and is best suited for short-cycle
repetitive jobs.
•Work sampling - Here, workers are observed many times at
random.
•Synthesis method - Here, the full job is divided into element or
parts.
•Predetermined motion time system (PMTS) - Here, normally,
three times are fixed for one job namely; normal, fast, and very-
fast.
•Analytical estimating - It is used for fixing the standard time for
jobs, which are very long and repetitive.

8. Table: Work measurement techniques and their application
Techniques Applications Unit of measurement
1. Time study Short cycle repetitive jobs.
Widely used for direct work.
Centiminute (0.01 min)
2. Synthetic Data Short cycle repetitive jobs. Centi minutes
3. Working sampling Long cycle
jobs/heterogeneous operations.
Minutes
4. MTM Manual operations confined to
one work centre.
TMU (1 TMU = 0.006 min)
5. Analytical estimation Short cycle non-repetitive job. Minutes

9. Basic Procedure to work measurement
There are various ways in which work may be measured and a variety of
techniques have been established. The basic procedure, irrespective of the
particular measurement technique being used, consists of three stages ;
•an analysis phase in which the job is divided into convenient, discrete
components, commonly known as elements;
•a measurement phase in which the specific measurement technique is used to
establish the time required (by a qualified worker working at a defined level
of performance) to complete each element of work;
•a synthesis phase in which the various elemental times are added, together
with appropriate allowances ,to construct the standard time for the complete
job.

10. Steps Involved in Work Measurement

1.Divide jobs into elements
2.Observe and record each element, any of the work measurement
techniques.
3.Set up unit time values, by extending observed time into normal
time for each unit. This can be done by applying rating factor.
4.Evaluate relaxation allowance and add the same to the normal time,
for each element to get the work content.
5.Ascertain the frequency of occurrence of each element in the job,
then multiply the work content to it. After that total the times to
reach the work content of the job.
6.Add contingency allowance, wherever required, to get the standard
time for performing the job.

11. Stop Watch Time Study

•Stop Watch Time Study is one of the equipment used for Time Study.
It is employed for measuring the time taken by an operator to complete
the work. Stop watch used for time study purpose should be very
accurate and preferably be graduated in decimals so that it can recover
even up to 0.01 minute.
•A large hand in the stop watch is revolved at a speed of one revolution
per minute. The dial of the stop watch is divided into 100 equal
divisions. The small hand inside the stop watch revolves at a speed of
one revolution in 30 minutes.

12. Procedure of Stop Watch Time Study

a) Analyse the job to establish the quality to be achieved in the job.
b) Identify key operations to be timed in the job.
c) Get improved procedure from the method study department.
d) Organise resources and explain the objectives of time study to the worker and
supervisor.
e) Explain details to worker about improved working procedure.
f) Break operation into elements to separate the constant elements from variable
elements.
g) Observe and record the time taken by an operator.
h) Determine for number cycles to be timed and then the average time or
representative time can be found out.
i) Rate of performance of the worker during observation.
j) Calculate normal time from observed time by using performance rating factor.
k) Add process allowance rest and personal allowance and special allowances to
the normal time in order to obtain standard time or allowed time.
l) Standard time determination by adding normal time and allowances.

13. Types of Stop Watch Study
There are three types of stop watches and they are:
1. Non-fly back stop watch,
2. Fly back stop watch, and
3. Split hand or split second type stop watch.



Non-fly back stop watch:
This stop watch is used for continuous timing. When the winding knob is
pressed for the first time, the watch starts and the long hand begins to move,
now if the winding knob is pressed for the second time, the long hand stops.
If the winding knob is pressed for the third time, the hand returns to zero
position.

14. Fly back stop watch:
•When two elements are to be timed and the second element is
immediately after the first element, fly back stop watch is required. In
a fly back stop watch, the watch is started and stopped with the help of
a slide.
•By pressing the wind knob, the hands are brought back to zero, but
they move forward again immediately without stopping. To stop the
hand at any point, the slide is used. This watch is used to take
continuous timing observation.

15. Split hand or split second type stop watch
A split hand stop watch is used to get greater accuracy when two elements
are to be timed and the second element is immediately after the first element.
The stop watch is started and the first element is observed.
After the completion of first elements the winding knob is pressed which
makes one hand to stop but the other hand keeps moving. After the reading
has been taken for the first element, the winding knob is pressed for the
second time which restarts the stopped hand making the two hands go
together.

16. Element used in Time Study
An element is a instinct part of a specified activity composed of one or more
fundamental motions selected for convenience of observation and timing. Measure
the time by means of a stop watch taken by the operator to perform each element of
the operation.
Repetitive Element
Occasional Element
Constant Element
Variable Element
Foreign Element

17. •A Repetitive Element:It is an element which occurs in every work cycle of
an operation.For example:the elements of picking up a part prior to an
assembly operation;the element of locating a workplace in a holding device.
•An Occasional Element:It is an element which does not occur in every work
cycle of an operation but which may occur at regular or irregular
intervals.For example:adjusting the tension or machine setting.The
occasional element is useful work of a part of the job.It will be incorporated
in the final standard time for the job.
•A Constant Element:It is an element for which the basic time remains
constant whenever it is performed.Example:switch on machine,gauge
diameter.
•A Variable Element:It is an element for which the basic time varies in
relation to some characteristics of the product,equipment or
process.Example:saw logs with handsaw;sweep floor;push trolley of parts to
next shop.
•A Foreign Element:It is an element observed which does not form a part of
the operation being studied.Example:in furniture manufacture sanding the
edge of a board before planning has been completed.

18. Qualified Workers
A qualified worker is one who has acquired the skill,knowledge and other
attributes to carry out the work in hand to satisfaction standards of
quantity,quality and safety.The acquisition of skill is a complicated
process.It has been observed that among the attributes which is
differentiate the experienced worker from the inexperienced are the
following.The experienced worker:
•1. Achieves smooth and consistent movements.
2. Acquire rhythm
3. Responds more rapidly to signals
4. Anticipates difficulties and is more ready to overcome them.
5. Carries out the task without giving the appearance of conscious
attention and is therefore more relaxed.

19. Representative Workers
The role of employee representatives in the context of a redundancy
exercise is to represent the views and opinions of their
constituent employees in the information and consultation process. ...
Consultation must be undertaken "with a view to reaching agreement"
with the employee representatives.

20. Job break down into elements
a) Account for variation in time —human, environmental, material and
equipment
b) Separate productive from unproductive activities
c) Increase accuracy in rating
d) Increase accuracy in assessing relaxation allowance by isolating those
elements containing different elements of fatigue
e) Produce a detailed work specification – easier to check for coverage,
insertions or omissions
f) Extract synthetic data for recurring elements

21. Work Cycle
Work Cycle means a period of time specifying a number of consecutive days
during which accrued time and approved leave will be accounted.

22. Number of Work Cycle

•Determine the sample size or number of readings that must be made for each
element, with a predetermined confidence level and accuracy margin. We can
apply a statistical method.

•The statistical method, we have first to take a number of preliminary readings (n’).
We then apply the following equation for the 95.45 confidence level and a margin
of error of ±5 per cent:

23. An example will make the point clear. Let us suppose that we take five
readings for a given element, and find that the value of the elapsed time in
1/100
ths
of a minute is 7, 6, 7, 7, and 6. We can then calculate the squares
and the sum of the squares of these numbers:

24. Allowance
Allowance is an amount of time added to the normal time to provide personal
delays, unavoidable delays and fatigue of the operator
Types of allowances
1.Relaxation allowances
Personal need allowances [washing hands, tea, laboratory] 5-7%
Fatigue allowances [excessive work, poor lighting, repeated work machine
noise, visual strain and mental strain]
2. Contingency allowances [Unavoidable allowances- tool sharpening, tool
replacing, coolant filling, discussion with supervisors, cleaning, power failure – 5%]
3. Process allowances [Loss of time due to no work, power failure, faulty material,
method, machine and operation ]
4. Interference allowances – [when one worker is attending more than one
machine]
5. Special allowances – not a part of operation cycle but essential for satisfactory
performance of the work
Start-up allowance & Shut- up allowance
Cleaning allowance & Tool allowance (for machine and tool)
Changeover allowancelays, unavoidable delays and fatigue of the operator

25. Performance Rating
Process of adjusting the actual pace of working of an operator by
comparing it with mental picture of pace of an operator working at
normal speed
Performance rating methods
Speed rating
Westing house method of rating (S,E,C,C)
Synthetic rating (R = P/A)
Objective rating

26. The two standard performance used for comparisons are as follows:
Normal Rating: It is the average rate at which a qualified worker will
work, even if he has no specific motivation.
Standard Rating: It is the average rate at which a qualified work will
be done if he is motivated to apply himself, to his work.
Basic Time:
•Basic time of a job is determined by multiplying rating factor to
the observed time (cycle time). Basic time is also expressed as
Normal time.
Basic time = (Observed time X Performance Rating)/100
Or
Basic Time = (Standard Time - Allowances)
In Basic Time no allowances are included

27. Steps in Making Time Study
Stop watch time is the basic technique for determining accurate time
standards. They are economical for repetitive type of work. Steps in taking
the time study are:

1. Select the work to be studied.
2. Obtain and record all the information available about the job, the operator
and the working conditions likely to affect the time study work.
3. Breakdown the operation into elements. An element is a instinct part of a
specified activity composed of one or more fundamental motions selected
for convenience of observation and timing.
4. Measure the time by means of a stop watch taken by the operator to
perform each element of the operation. Either continuous method or snap
back method of timing could be used.
5. At the same time, assess the operators effective speed of work relative to
the observer‟s concept of „normal‟ speed. This is called performance rating.

28. 6. Adjust the observed time by rating factor to obtain normal time for each
element
Normal =Observed time* Rating /100

7. Add the suitable allowances to compensate for fatigue, personal needs,
contingencies. etc. to give standard time for each element.
8. Compute allowed time for the entire job by adding elemental standard times
considering frequency of occurrence of each element.
9. Make a detailed job description describing the method for which the standard
time is established.

29. Computation of Standard Time
Standard time is the time allowed to an operator to carry out the specified task
under specified conditions and defined level of performance. The various
allowances are added to the normal time as applicable to get the standard time.

Standard time may be defined as the, amount of time required to complete a
unit of work:
(a)under existing working conditions,
(b) using the specified method and machinery,
(c) by an operator, able to the work in a proper manner, and
(d) at a standard pace.
Thus basic constituents of standard time are:
1.Elemental (observed time).
2.Performance rating to compensate for difference in pace of working.
3.Relaxation allowance.
4.Interference and contingency allowance. 5. Policy allowance.

30. Components standard time
OT – Observed Time
PRF – Performance Rating Factor
NT – Normal Time
PA – Process Allowances
RPA – Rest and Personal Allowances
SA – Special Allowances
PoA – Policy Allowances

32. ILLUSTRATION-01

33. ILLUSTRATION-02

34. ILLUSTRATION-03