Work study work measurement

WORK STUDY
WORK MEASUREMENT
JOSEPH GEORGE KONNULLY

Definition of Work Measurement

Objectives and uses of WM
OBJECTIVES AND USES OF WORK MEASUREMENT
The main objectives of work measurement:
1. Manpower planning.
2. Production planning and scheduling.
3. Estimating productions costs.
4. Cost reduction and control.
5. Rational basis for incentives.
6. Performance appraisal.
7. Training of employees.
8. Comparing alternative methods.
9. Accepting new orders.
10. Fixing the selling cost.

Techniques/Methods/Types of WM

METHODS OF WORK MEASUREMENT
1. Historical data method
Historical data method uses the past-performance data. Here, past performance is used as a
guideline for setting work performance standards. The main advantage of this technique is that
it is simple to understand, quicker to estimate and easier to implement. However, past
performance is not the best basis for fixing performance standards. This is because there may
be many changes in technology, employees’ behavior, abilities, etc.
2. Time study
Time study with the help of a stop watch is the most commonly used work measurement
method. This technique was developed by Frederick Winslow Taylor (1856-1915).
Time study is best suited for short-cycle repetitive jobs. Most of the production jobs can be
easily timed by a time-study.
Time study procedure consists of the following steps:
Select the job to be timed.
Standardize the method of doing the job.
Select the worker to be studied.
Record the necessary details of the job and conditions of work.
Divide the job into elements. Here, ’element’ is a part of the job.
Find out the time taken to do every single element.
Keep provisions for relaxation, etc.
Fix the standard time for doing the job.

3. Work sampling
Work sampling method was original developed by Leonard Henry Caleb Tippett (1902-1985) in Britain in 1934. In this
technique, the workers are observed many times at random. It is done to find out for how much time the worker is actually
on the job. It checks how long he is working and how much time he is not working (idle time).
Work sampling method does not involve stop watch measurement. The purpose of work sampling technique is to estimate
what proportion of a worker’s time is devoted to work-related activities.
Work sampling method involves following three main steps:
Deciding what activities are defined as ’working’. Non-working are those activities which are not defined as working.
Observe the worker at selected intervals and record (write down) whether he is working or not.
Calculate the portion of time (P), a worker is working.
A portion of time (P) a worker is working equals to ’Number of observations during which working occurred’ divided by ’Total
Number of observations.’
The above calculation is used as a performance standard.
Advantages of Work Sampling
The benefits or advantages of work sampling method are as follows:
Work sampling gives an unbiased result since workmen are not under close observation.
A work sampling study may be interrupted at any time without affecting the results.
Work sampling can be conducted by anyone with limited training. There is no need to have experts.
Team work can be studied by work sampling and not by the time-study.
Work sampling is economical and less time-consuming than time study. This is because more than one worker can be
studied at the same time. Secondly, observer needs not to be present himself for a long time.
Disadvantages of Work Sampling
The limitations or disadvantages of work sampling method are as follows:
Work sampling is not economical for short cycle jobs. It is also uneconomical to study a single worker or even small group of
workers.
Unlike time study, it does not allow a small breakdown of activities and delays.
Working men may change their normal method of working when they see an observer. Therefore, the results from the work
study may not be accurate.
In work sampling method, the observations are limited or insufficient. So, the results may not be accurate.
This method normally does not record the workers' speed of working.

4. Synthesis method
In synthesis method, the full job is first divided into elements (parts). Then the time taken
to do each element of the job is found out and synthesized (totaled). This gives the total
time taken for doing the full job. In this technique, the time taken to do each element of
the job is found out from previous time studies. So, this technique gives importance to
past-time studies of similar jobs. It also uses standard data.
Standard-data is the normal time taken for doing routine jobs. Standard data is easily
available for routine-jobs like fitting screws, drilling holes, etc. So there is no need of
calculating these times repeatedly. Most companies use Standard-data. They do not
waste time doing studies for all elements of the job. This is because standard time is
already available for most elements of a job.
For example, a job of publishing a book contains four elements viz; typing, editing,
printing and binding. The time taken for doing each element is first found out. Suppose,
typing takes 40 days, editing takes 30 days; printing takes 20 days and binding takes 10
days. Then the time taken to do all the elements are totaled. That is, it takes 40 + 30 + 20
+ 10 = 100 days to publish a book. This information is taken from previous time studies of
other printing jobs or from the standard data.
Synthesis technique also considers the level of performance. Level of performance refers
to the speed of performance, which is either, normal, fast, or very-fast.
The benefits or advantages of synthesis method:
It provides reliable information about standard time for doing different jobs. This is
because it is based on many past time studies.
It is economical because there is no need to conduct new time studies.

5. Predetermined motion time system
In ’Predetermined Motion Time System’ method or simply PMTS technique,
the normal times are fixed for basic human motions. These time values are
used to fix the time required for doing a job. Normally, three times are fixed for
one job. That is, one time is fixed for each level of performance. The level of
performance may be normal, fast and very-fast.
PTMS is better than motion studies because it gives the detailed analysis of
the motion, and it fixes the standard time for doing that motion.
PTMS technique is used mostly for jobs, which are planned for future.
However, it can also be used for current jobs as an alternative to time study.
The benefits or advantages of PMTS method:
It is a very accurate method. It avoids subjective judgement or bias of rater.
It is an effective and economical method for repetitive jobs of short duration.
There is no interference in the normal work routine, and so it does not face any
resistance from the employees.
It helps to improve the work methods because it gives a detailed analysis of
the motions.
It is more economical and fast compared to normal time studies.

• 6. Analytical estimating
• Analytical estimating method or technique is used for fixing the
standard time for jobs, which are very long and repetitive. The
standard-time is fixed by using standard-data. However, if standard
data is not available, then the standard time is fixed based on the
experience of the work-study engineer.
• The benefits or advantages of analytical estimating technique:
• It helps in planning and scheduling the production activities.
• It provides a basis for fixing labor rate for non-repetitive jobs.
• It is economical because it uses standard data for fixing the standard
time of each job.
• One disadvantage or limitation of analytical estimating method:
• When standard-data is not available for a job, then the standard time
is fixed by the work-study engineer. He uses his experience and
judgement for estimating the standard-time. This is not accurate
compared to a scientific time study.
• So, these are different techniques of work measurement.

SUMMARY OF WORK MEASUREMENT METHODS AND ITS USES
Techniques Applications Unit of measurement
1. Time study
2. Synthetic Data
3. Working sampling
4. MTM/PMTS
5. Analytical estimation
Short cycle repetitive jobs
Widely used for direct work.
Short cycle repetitive jobs.
Long cycle jobs/heterogeneous
Manual Operations confined to
one work centre
Long-cycle non-repetitive job.
Centiminute (0.01 min)
Centiminute(0.01 min)
Minutes
TMU (1 TMU = 0.006 min)
Minutes

Method of measuring time with a Stop Watch
There are two methods of timing using a stop watch. They are
1.Fly back or Snap back method.
2.Continuous or Cumulative method.
Fly back method
Here the stop watch is started at the beginning of the first element. At the end of
the element the reading is noted in the study sheet (in the WR column). At the
same time, the stop watch hand is snapped back to zero. This is done by pressing
down the knob, immediately the knob is released. The hand starts moving from
zero for timing the next element. In this way the timing for each element is found
out. This is called observed time (O.T.) .
Continuous method
Here the stop watch is started at the beginning of the first element. The watch runs
continuously throughout the study. At the end of each element the watch readings
are recorded on the study sheet. The time for each element is calculated by
successive subtraction. The final reading of the stop watch gives the total time.
This is the observed time (O.T.).

Steps in making Stop watch 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.
6. Adjust the observed time by rating factor to obtain normal time for each element
Normal Time = 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.
10. Test and review standards wherever necessary.

Definitions 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 as
shown in Fig. 7.6.
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.(PRF)
3. Relaxation allowance.
4. Interference and contingency allowance.
5. Policy allowance.

Components of Standard Time
• OT – Observed Time
• PRF – Performance Rating Factor
• NT – Normal Time
• PA – Process Allowances
• RPA – Rest and Personal Allowances (Relaxation Allowance)
• SA – Special Allowances( Interference and Contingency Allowances)
• PoA – Policy Allowances
• PFD – Personal , Fatigue and Delay Allowances = (PA+RPA+SA)
• The Standard Time is the product of three factors:
• 1.Observed time: The time measured to complete the task.
• 2.Performance rating factor: The pace the person is working at. 90% is working slower than normal, 110% is working faster
than normal, 100% is normal. This factor is calculated by an experienced worker who is trained to observe and determine the
rating.
• 3.Personal, fatigue, and delay (PFD) allowance.
• The standard time can then be calculated by using the formula:
•

Computation of Standard Time Illustrations
• ILLUSTRATION 1: Assuming that the total observed time for an operation of
• assembling an electric switch is 1.00 min. If the rating is 120%, find normal time. If an
• allowance of 10% is allowed for the operation, determine the standard time.
• SOLUTION:
• Obsersved time (or) selected time = 1.00 min
• Rating = 120%
• Allowance = 10%
• As we know that, normal time = Observed time × Rating % ÷ 100 = 1.00 ×120 ÷10=1.20min
• Allowance @ 10% = 1.20 ×10 ÷ 100 = 0.12 min
• ∴ Standard time = Normal time + Allowances
• = 1.20 + 0.12 = 1.32 min.
• ILLUSTRATION 2: An operator manufactures 50 jobs in 6 hours and 30 minutes.
• If this time includes the time for setting his machine. Calculate the operator’s efficiency.
• Standard time allowed for the job was:
• Setting time = 35 min
• Allowed time per piece = 8 min
• SOLUTION:
• As standard time = Set up time + Time per piece × No. of pieces produced
• ∴ Standard time for manufacturing 50 jobs
• = 35 + 8 × 50
• = 435 min
• = 7 hours and 15 min.
• Efficiency of operator =Standard time × 100 ÷ Actual time = 435× 100 ÷ 390 = 111.5%.

ILLUSTRATION 3: Following datas were obtained by a work study. Man from a
study conducted by hours.
(i) Maintenance time
(a) Get out and put away tools = 12.0 min/day
(b) Cleaning of machine = 5.0 min/day
(c) Oiling of machine = 5.0 min/day
(d) Replenish coolant supply = 3.0 min/day
(ii) Interruption
(a) Interruption by foreman = 5.0 min/day
(b) Interruption by porter etc. = 4.0 min/day
(iii) Delay time due to power failure etc. = 6.0 min/day
(iv) Personal time = 20.0 min/day
Calculate total allowances, total available cycle time productive hours, considering a
working day of 8 hours.
SOLUTION:
Total allowance (sometimes also known as station time)
= Total maintenance time + Interruption time
+ Delay time + Personal time
= (12.0 + 5 + 5 + 3.0) + (5.0 + 4.0) + 6.0 + 20.0
= 25.0 + 9.0 + 6.0 + 20.0
= 60.0 min per day
∴ Total available cycle time = Total work period – Total allowances
= 480 – 60 = 420 min/day
Productive hours =Time available Number of hours = 420 ÷60 = 7 hrs

ILLUSTRATION 4: Find out the standard time using the following
data:
Average time for machine elements = 6 min
Average time for manual elements = 4 min
Performance rating = 110%
Allowances = 10%
SOLUTION:
Normal time = Machinery time + Manual time × Rating
= 6 + 4 × 1.1
= 6 + 4.4 = 10.4 min
∴ Standard time = Normal time + Allowances
= 10.4 + 10.4 ×10 ÷ 100
= 10.4 (1 + 0.1) = 11.44 min.

Work study work measurement

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Work study work measurement