Considered as a valuable tool in increasing productivity.
Definition: Work study is a generic term for the techniques of method study and work
measurement.
These techniques are used in the examination of human work in all its contexts. They lead
systematically to the investigation of all the factors which affect the efficiency and economy at
the
1.1.METHOD STUDY
Method study is the technique of systematic recording and critical examination of
existing and
proposed ways of doing work and developing an easier and economical method.
1.1.1 Objectives of Method Study
1. Improvement of manufacturing processes and procedures.
2. Improvement of working conditions.
3. Improvement of plant layout and work place layout.
4. Reducing the human effort and fatigue.
5. Reducing material handling
7. Improvement in the utility of material, machines and manpower.
8. Standardisation of method.
1.2. BASIC PROCEDURE FOR METHOD STUDY
The basic procedure for conducting method study is as follows:
1. Select the work to be studied.
2. Record all facts about the method by direct observation.
3. Examine the above facts critically.
4. Develop the most efficient and economic method.
5. Define the new method.
6. Install the new method
7. Maintain the new method by regular checking.
1. Select
While selecting a job for doing method study, the following factors are considered:
(a) Economical factors.
(b) Human factors.
(c) Technical factors.
(a) Economical Factors
The money saved as a result of method study should be sufficiently more. Then only the study
will
be worthwhile. Based on the economical factors, generally the following jobs are selected.
(a) Operations having bottlenecks (which holds up other production activities).
(b) Operations done repetitively.
(d) Operations where materials are moved for a long distance.
(b) Human Factors
The method study will be successful only with the co-operation of all people concerned viz.,
workers,
1. The fear of unemployment.
2. The fear of reduction in wages.
3. The fear of increased work load.
then if they do not accept method study, the study should be postponed.
(c) Technical Factors
To improve the method of work all the technical details about the job should be
available. Every machine tool will have its own capacity. Beyond this, it cannot be improved.
For example, a work
study man feels that speed of the machine tool may be increased and HSS tool may be used. But
the capacity of the machine may not permit increased speed. In this case, the suggestion of the
work study man cannot be implemented. These types of technical factors should be considered.
2. Record
All the details about the existing method are recorded. This is done by directly observing
the work.
Symbols are used to represent the activities like operation, inspection, transport, storage and
delay.
Different charts and diagrams are used in recording. They are:
1. Operation process chart: All the operations and inspections are recorded.
2. Flow process chart
(a) Man type All the activities of man are recorded
(b) Material type All the activities of the material are recorded
(c) Equipment type All the activities of equipment or machine are recorded.
3. Two-handed process chart: Motions of both lands of worker are
Right hand-Left hand chart recorded independently.
4. Multiple activity chart: Activities of a group of workers doing a single job or the
activities of a
single worker operating a number of machines are recorded.
5. Flow diagram: This is drawn to suitable scale. Path of flow of material in the shop is
recorded.
6. String diagram: The movements of workers are recorded using a string in a diagram
drawn to
3. Examine
Critical examination is done by questioning technique. This step comes after the
method is recorded by suitable charts and diagrams.
The individual activity is examined by putting a number of questions.
The following factors are questioned
1. Purpose – To eliminate the activity, if possible.
2. Place – To combine or re-arrange the activities.
3. Sequence – -do-
4. Person – -do-
The following sequence of questions is used:
1. Purpose – What is actually done?
Why is it done?
What should be done?
Why is it done there?
Where else could it be done?
Where should it be done?
3. Sequence – When is it done?
Why is it done then?
When could it be done?
When should it be done?
4. Person – Who is doing it?
Why does that person do it?
Who else could do it?
Who should do it?
How should it be done?
By doing this questioning
Number of activities can be combined or re-arranged
Method can be simplified.
4. Develop
The answer to the questions given below will result in the development of a better method.
1. Purpose – What should be done?
2. Place – Where should it be done?
3. Sequence – When should it be done?
4. Person – Who should do it?
5. Means – How should it be done?
5. Define
Once a complete study of a job has been made and a new method is developed, it is
necessary to
obtain the approval of the management before installing it. The work study man should prepare a
report giving details of the existing and proposed methods. He should give his reasons for the
changes
(a) Brief description of the old method.
(b) Brief description of the new method.
(c) Reasons for change.
(f) Tools and equipment required for the new method.
(g) The cost of installing the new method including.
1. Cost of new tools and equipment.
2. Cost of re-layout of the shop.
3. Cost of training the workers in the new method.
4. Cost of improving the working conditions.
Written standard practice: Before installing the new method, an operator‘s instructions sheet
called written standard practice is prepared. It serves the following purposes:
1. It records the improved method for future reference in as much detail as may be
necessary.
2. It is used to explain the new method to the management foreman and operators.
3. It gives the details of changes required in the layout of machine and work places.
4. It is used as an aid to training or retraining operators.
5. It forms the basis for time studies.
The written standard practice will contain the following information:
(a) Tools and equipment to be used in the new method.
(b) General operating conditions.
(c) Description of the new method in detail.
(d) Diagram of the workplace layout and sketches of special tools, jigs or fixtures
required.
6. Install
This step is the most difficult stage in method study. Here the active support of both
management
and trade union is required. Here the work study man requires skill in getting along with other
people and winning their trust. Instal stage consists of
(a) Gaining acceptance of the change by supervisor.
(b) Getting approval of management.
(c) Gaining the acceptance of change by workers and trade unions.
(d) Giving training to operators in the new method.
(e) To be in close contact with the progress of the job until it is satisfactorily executed.
7. Maintain
The work study man must see that the new method introduced is followed. The workers
after some time may slip back to the old methods. This should not be allowed. The new method
may have defects. There may be difficulties also. This should be rectified in time by the work
study man. Periodical review is made. The reactions and suggestions from workers and
supervisors are noted. This may lead to further improvement. The differences between the new
written standard practice and the actual practice are found out. Reasons for variations are
analysed. Changes due to valid reasons are accepted. The instructions are suitably modified.
1.3 CHARTS AND DIAGRAMS USED IN METHOD STUDY (TOOLS AND
TECHNIQUES)
As explained earlier, the following charts and diagrams are used in method study.
1. Operation process chart (or) Outline process chart.
2. Flow process chart.
4. Multiple activity chart.
1.3.1 Process Chart Symbols
The recording of the facts about the job in a process chart is done by using standard
symbols.
Using of symbols in recording the activities is much easier than writing down the facts about the
job. Symbols are very convenient and widely understood type of short hand. They save a lot of
writing and indicate clearly what is happening.
1. Operation
A large circle indicates operation. An operation takes place when there is a change in
physical or
chemical characteristics of an object. An assembly or disassembly is also an operation.
When information is given or received or when planning or calculating takes place it is also
called operation.
Example 1.1
Reducing the diameter of an object in a lathe. Hardening the surface of an object by heat
treatment.
2. Inspection
A square indicates inspection. Inspection is checking an object for its quality, quantity or
identifications.
Example 1.2
Checking the diameter of a rod. Counting the number of products produced.
3. Transport
An arrow indicates transport. This refers to the movement of an object or operator or
equipment
from one place to another. When the movement takes place during an operation, it is not called
transport.
Operator going to the stores to get some tool.
4. Delay or temporary storage
A large capital letter D indicates delay. This is also called as temporary storage. Delay occurs
when an object or operator is waiting for the next activity.
Example 1.4
An operator waiting to get a tool in the stores. Work pieces stocked near the machine before
the next operation.
5. Permanent storage
An equilateral triangle standing on its vertex represents storage. Storage takes place when an
object
Example 1.5
6. Combined activity
When two activities take place at the same time or done by the same operator or at the same
place, the two symbols of activities are combined.
Example 1.6
Reading and recording a pressure gauge. Here a circle inside a square represents the combined
activity of operation and inspection.
1.3.2 Operation Process Chart
An operation process chart is a graphic representation of the sequence of all operations and
inspections taking place in a process. It is also known as outline process chart. It gives a bird‘s
eye view of the overall activities. Entry points of all material are noted in the chart.
An example of operation process chart is shown in the figure 1.2. Here the process of
manufacture of electric motor is shown.
The conventions followed in preparing the chart are
1. Write title at the top of the chart.
2. Begin the chart from the right hand side top corner.
3. Represent the main component at the right extreme.
4. Represent the sequence of operations and inspections by their symbols. Connect them
by
vertical flow lines.
5. Record the brief description of the activity to the right side of the symbols.
6. Note down the time for each activity to the left of the symbol.
7. Number all operations in one serial order. Start from the right hand top (from number
1).
8. Similarly number all inspections in another serial order (starting from 1).
9. Continue numbering, till the entry of the second component.
10. Show the entry of purchased parts by horizontal lines.
1.3.3 Flow Process Chart
A flow process chart is a graphical representation of the sequence of all the activities
(operation,
inspection, transport, delay and storage) taking place in a process. Process chart symbols are
used
here to represent the activities. There are three types of flow process charts. They are
1. Man type flow process chart
This flow process chart records what the worker does.
2. Material type flow process chart
This flow process chart records how the material is handled or treated.
3. Equipment type flow process chart
This flow process chart records how the equipment or machine is used.
Example 1.7
The activities of a stenographer in preparation of a letter are recorded in the operator type
flow process chart shown in figure 1.3.
The chart records the activities of the steno. Here, the manager calls the steno and
dictates a letter. The steno takes notes of the letter, types it, gets the signature of the manager and
sends it for dispatching. These activities are shown in the chart. This is operator type flow
process chart. Considering the message in the letter as material, we can prepare the material type
flow process chart.
General guidelines for making a flow process chart
1. The details must be obtained by direct observation—charts must not be based on
memory.
3. No assumptions should be made.
4. Make it easy for future reference.
5. All charts must have the following details:
(a) Name of the product, material or equipment that is observed.
(b) Starting point and ending point.
(c) The location where the activities take place.
(d) The chart reference number, sheet number and number of total sheets.
(e) Key to the symbols used must be stated.
1.3.4 Two-Handed Process Chart (or) Right Hand, Left Hand Chart
It is the process chart in which the activities of two hands of the operator are
recorded.
It shows whether the two hands of the operator are idle or moving in relation to
one another, in a timescale.
It is generally used for repetitive operations.
Operation: Represents the activities grasp, position, use, release etc. of a tool,
component or
material.
Transport: Represents the movement of the hand or limb to or from the work or a tool
or material.
Delay: Refers to the time when the hand or limb is idle.
Storage (Hold): The term hold‘ is used here instead of storage. This refers to the time
when the
work is held by hand.
The activity inspection‘ by hand is considered as an operation. Hence, the symbol for
inspection
is not used in this chart.
Two-handed process chart can be used for assembly, machining and clerical jobs.
General guidelines for preparing the chart
1. Provide all information about the job in the chart.
2. Study the operation cycle a few times before starting to record.
3. Record one hand at a time.
4. First record the activities of the hand which starts the work first.
5. Do not combine the different activities like operations, transport etc.
Example 1.8
Example of a two-handed process chart is shown in figure 1.4. Here the assembly of a nut
and washer over a bolt is recorded.
The work place layout is shown in the right hand corner. The activities of left hand are
recorded
at left half of the chart. The activities of the right hand are recorded at the right half of the chart.
The horizontal lines represent the time scale. Activities of left hand and right hand shown
in
the same line occur at the same moment.
Summary of the number of each activity can be tabulated at the bottom of the chart. The
chart is first drawn for the existing method. This chart is analysed and if it is found that one hand
is over loaded than the other, modification are done in the layout of the workplace or in the
sequence of activities. Then a new chart is made for the proposed cycle.
1.3.5 Man-Machine Chart
A man-machine chart is a chart in which the activities of more than one worker or machine
are
recorded. Activities are recorded on a common time scale to show the inter-relationship. It is also
known as multiple activity chart.
It is used when a worker operates a number of machines at a time. It is also used when a
number of workers jointly do a job.
Activities of workers or machines are recorded in separate vertical columns (bars) with a
horizontal time scale.
The chart shows the idle time of the worker or machine during the process.By carefully
analyzing the chart, we can rearrange the activities. Work load is evenly distributed among the
workers or machines by this the idle time of worker or machine is reduced. Multiple activity
chart is very useful in planning team work in production or maintenance. Using the chart we can
find out the correct number of machines that a worker can operate at a time. We can also find out
the exact number of workers needed to do a job jointly.
To record the time, ordinary wrist watch or stop watch is used. High accuracy is not needed.
Man-machine chart is a type of multiple activity chart. Here, the activities of a number of
machines are recorded.
An example of man-machine chart is shown in figure 1.5. Here one operator two semi-
automatic
machines simultaneously. The activities of the operator is recorded in a separate vertical column.
The activities of the two machines are recorded in two separate vertical columns. The different
activities like loading, machining and unloading are represented by different symbols. Blank
space shows the idle time.
1.3.6 Flow Diagram
In any production shop, repair shop or any other department, there are movements of
men and
material from one place to another. Process charts indicate the sequence of activities. They do
not show the frequent movements of men and material. If these movement are minimized, a lot
of savings can be achieved in cost and effort. If the path of movement of material is not frequent
and simple, a flow diagram is used for recording the movement.
A flow diagram is a diagram which is drawn to scale. The relative position of
machineries, gang ways, material handling equipment etc. are drawn first. Then the path
followed by men or material is marked on the diagram. Different movements can be marked in
different colours. Process symbols are added to the diagram to identify the different activities at
different work centres.
1. To remove unwanted material movement.
2. To remove back tracking.
3. To avoid traffic congestion.
4. To improve the plant layout.
Conventions adopted are
1. Heading and description of the process should be given at the top of the diagram.
2. Other informations like location, name of the shop, name of the person drawing the
diagram
are also given.
3. The path followed by the material is shown by a flow line.
4. Direction of movement is shown by small arrows along the flow lines.
5. The different activities are represented by the symbols on the flow lines. (Same symbols
used in flow process chart are used here).
6. If more than one product is to be shown in the diagram different colours are used for
each
path.
1.3.7 String Diagram
We make use of flow diagram for recording the movement of men or material when the
movement is simple and the path is almost fixed. But when the paths are many and are repetitive,
it may not be possible to record them in a flow diagram. Here a string diagram is used.
String diagram is a scaled plan of the shop. Location of machines and various facilities are
drawn to scale in a drawing sheet. Pins are fixed at the various work centres in the drawing sheet.
A continuous coloured thread or string is taken round the pins where the material or worker
moves during the process.
Constructions
1. Draw the layout of the shop to scale in a drawing sheet.
2. Mark the various work centres like machines, stores, work bench etc. in the diagram.
3. Hold the drawing sheet on a soft board and fix pins at the work centres.
4. Tie one end of a coloured string to the work centre from which the movement starts.
5. Follow the path of the worker to different work centre and accordingly take the thread to
different points on the drawing board.
6. At the end of the session note down the number of movements from one work centre to
another.
7. Remove the string and measure the total length of the string. Multiply by the scale and
get the actual distance of movement.
Applications
1. It is used for recording the complex movements of material or men.
2. Back tracking, congestion, bottlenecks, under utilized paths are easily found out.
3. It is used to check whether the work station is correctly located.
4. Used to record irregular movements.
5. Used to find out the most economical route.
1.4 WORK MEASUREMENT
Work measurement is a technique to establish the time required for a qualified worker to
carry out
Objectives of work measurement
2. To fix the standard time for doing a job.
3. To develop standard data for future reference.
4. To improve methods.
Uses of work measurements
1. To compare the efficiency of alternate methods. When two or more methods are available
for doing the same job, the time for each method is found out by work measurement. The
method which takes minimum time is selected.
2. Standard time is used as a basis for wage incentive schemes.
3. It helps for the estimation of cost. Knowing the time standards, it is possible to work out
the cost of the product. This helps to quote rates for tenders.
4. It helps to plan the workload of man and machine.
5. It helps to determine the requirement of men and machine. When we know the time to
produce one piece and also the quantity to be produced, it is easy to calculate the total
requirement of men and machines.
6. It helps in better production control. Time standards help accurate scheduling. So the
production control can be done efficiently.
7. It helps to control the cost of production. With the help of time standards, the cost of
production can be worked out. This cost is used as a basis for control.
8. It helps to fix the delivery date to the customer. By knowing the standard time we will be
able to calculate the time required for manufacturing the required quantity of products.
1.5 TECHNIQUES OF WORK MEASUREMENT
The different techniques used in work measurement are
1. Stop watch time study.
2. Production study.
4. Synthesis from standard data.
5. Analytical estimating.
6. Predetermined motion time system.
1.5.1 Stop Watch Time Study
Stop watch time study is one of the techniques of work measurement commonly used.
Here we
make use of a stop watch for measuring the time.
Procedure for conducting stop watch time study
The following procedure is followed in conducting stop watch time study:
1. Selecting the job.
2. Recording the specifications.
4. Examining each element.
8. Determining the allowances.
1. Selection of job
Time study is always done after method study. Under the following situations, a job is
selected for
time study:
1. A new job, new component or a new operation.
2. When new time standard is required.
3. To check the correctness of the existing time standard.
4. When the cost of operation is found to be high.
5. Before introducing an incentive scheme.
6. When two methods are to be compared.
2. Record
1. About the product-name, product-number, specification.
2. About the machine, equipment and tools.
3. About the working condition-temperature-humidity-lighting etc. These informations are
used
when deciding about the allowances.
4. About the operator name-experience-age etc. This is needed for rating the operator.
3. Break down operation into elements
Each operation is divided into a number of elements. This is done for easy observation and
accurate
measurement. The elements are grouped as constant element, variable element, occasional
element, man element, machine element etc.
4. Examine each element
The elements are examined to find out whether they are effective or wasteful. Elements are
also examined whether they are done in the correct method.
5. Measure using a stop watch
The time taken for each element is measured using a stop watch. There are two methods
of measuring. viz., Fly back method and Cumulative method. Cumulative method is preferable.
The time measured from the stop watch is known as observed time. Time for various groups
of elements should be recorded separately. This measurement has to be done for a number of
times. The number of observations depend upon the type of operation, the accuracy required and
time for one cycle.
6. Assess the rating factor
Rating is the measure of efficiency of a worker. The operator‘s rating is found out by
comparing
his speed of work with standard performance. The rating of an operator is decided by the work
study man in consultation with the supervisor. The standard rating is taken as 100. If the operator
is found to be slow, his rating is less than 100 say 90. If the operator is above average, his rating
is more than 100, say 120.
7. Calculate the basic time
Basic time is calculated as follows by applying rating factor
8. Determine the allowance
A worker cannot work all the day continuously. He will require time for rest going for
toilet, drinking water etc. Unavoidable delays may occur because of tool breakage etc. So some
extra time is added to the basic time. The extra time is known as allowance.
9. Compile the standard time
The standard time is the sum of basic time and allowances. The standard time is also known
as allowed time.
1.5.1.1 Breaking a Job into Elements
It is necessary to break down a task (job) into elements for the following reasons:
1. To separate productive time and unproductive time.
2. To assess the rating of the worker more accurately.
3. To identify the different types of elements and to measure their timings separately.
4. To determine the fatigue allowance accurately.
5. To prepare a detailed work specification.
6. To fix standard time for repetitive elements (such as switch on or switch off of
machine).
Classification of elements
1. Repetitive elements
It is an element which occurs in every work cycle of the job.
Example 1.9
2. Constant element
It is an element for which the basic time remains constant whenever it is performed.
Example 1.10
3. Variable element
It is an element for which the basic time varies depending on the characteristics of
the product, equipment or process.
Example 1.11
Saving a log of wood-time changes with diameter or the work.
4. Occasional element
It is an element which does not occur in every work cycle of the job. It may occur
at regular or irregular intervals.
Example 1.12
5. Foreign element
It is an element which is not a part of the job.
Example 1.13
6. Manual element
Example 1.14
7. Machine element
It is the element automatically performed by a power driven machine.
Example 1.15
Turning in a lathe using automatic feed.
General rules to be followed in breaking down a task into elements
1. Element should have a definite beginning and ending.
2. An element should be as short as possible so that it can be conveniently timed.
The shortest element that can be timed using a stop watch is 0.04 mt.
3. Manual elements and machine elements should be separately timed.
4. Constant element should be separated from variable elements.
5. Occasional and foreign elements should be timed separately.
1.5.1.2 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.
1. 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.) .
2. 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.).
1.6 CALCULATION OF BASIC TIME
Basic time is the time taken by an operator of standard performance (rating of 100). A
man whose work is observed, may be a slow worker or a fast worker. His rating may be less than
100 or above 100. The observed time cannot be taken as the basic time. Here the rating factor is
applied and basic time is calculated as follows.
For example, assume that observed time for an operation is 0.7 mts. The rating of the
operator
1.7 ALLOWANCES
2. Process allowance.
3. Contingency allowance.
4. Special allowance.
5. Policy allowance.
1.8 CALCULATION OF STANDARD TIME
Standard time or allowed time is the total time in which a job should be completed at
standard
performance. It is the sum of normal time (basic time) and allowances. Policy allowance is not
included.
Standard time is worked out in a stop watch time study in the following manner.
Observed time
This is the actual time observed by using a stop watch. The observed time of an operation is
the
total of the elemental times.
The time study for the same job is conducted for a number of times. The average of the
observed times is calculated.
Basic or normal time
Basic time is the time taken by a worker with standard performance. Basic time is calculated
from
Allowed time or standard time
The standard time is obtained by adding the following allowances with the basic or
normal time.
2. Process allowance or unavoidable delay allowance.
3. Contingency allowance.
4. Special allowance.
Policy allowance may be added to the standard time if the management wants.
1.9 PRODUCTION STUDY
Production study is a technique of work measurement to check accuracy of the original time
study. This study is done to find the time delay due to occasional elements. These elements may
occur at irregular intervals. Example: Tool grinding, setting tools etc. There are chances of
missing these elements in the stop watch time study. Production study is conducted for a longer
period—at least for half a day or one shift.
1.10 RATIO DELAY STUDY
This study is also known as work sampling or activity sampling. Here the ratio of the
delay time and working time to the total time of an activity is found out. This is done by random
(irregular) observations. This study is applied to
1. Long cycle operations.
1.11 SYNTHESIS FROM STANDARD DATA
Synthesis is a work measurement technique to work out standard time for a job by totaling
the elemental times already obtained from previous time studies. Many operators in an industry
have several common elements. Example: starting the machine, stopping the machine etc.
Whenever these activities occur, they take the same duration of time. These elements are called
constant elements. Time for some elements vary proportionately with the speed, feed, length of
cut etc. in machining operation. These elements are known as variable elements. Time for all
these constant elements and variable elements are collected from the time studies previously
made. These are stored in a file. This is called time standard data bank. Data bank contains data
in the form of
2. Charts and graphs.
3. Formulae etc.
1.12 ANALYTICAL ESTIMATING
Setting the time standards for long and non-repetitive operations by stop watch method
are uneconomical. Analytical estimating technique determines the time values for such jobs
either by using the synthetic data or on the basic of the past experience of the estimator when no
synthetic or standard data is available. In order to produce accurate results the estimator must
have sufficient experience of estimating, motion study, time study and the use of synthesized
time standards.
1.13 PREDETERMINED MOTION TIME SYSTEM (PMTS)
Definition: PMTS is a work measurement technique where by times, established 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. Few well-
known systems using this concept are
1. M.T.M. : Method Time Measurement.
2. W.F.S. : Work Factor System.
3. M.T.A. : Motion Time Analysis.
4. D.M.T. : Dimensional Motion Times.
5. B.M.T. : Basic Motion Times.
1.14 ERGONOMICS
Ergons means work‘ and Nomos means Natural laws‘. Ergonomics or its American
equivalent Human Engineering may be defined as the scientific study of the relationship
between man and his working environments. Ergonomics implies Fitting the job to the worker‘.
Ergonomics combines the knowledge of a psychologist, physiologist, anatomist, engineer,
anthropologist and a biometrician.
1.14.1 Objectives
The objectives of the study of ergonomics is to optimize the integration of man and
machine in
order to increase work rate and accuracy. It involves
1. The design of a work place befitting the needs and requirements of the worker.
2. The design of equipment, machinery and controls in such a manner so as to minimize
mental
and physical strain on the worker thereby increasing the efficiency, and
3. The design of a conductive environment for executing the task most effectively.
Both work study and Ergonomics are complementary and try to fit the job to the workers;
however Ergonomics adequately takes care of factors governing physical and mental strains.
1.14.2 Applications
In practice, ergonomics has been applied to a number of areas as discussed below
1. Working environments 2. The work place, and 3. Other areas.
1. Working environments
(i.e.,
temperature, humidity and fresh air circulation), noise, bad odour, smokes, fumes, etc., which
affect the health and efficiency of a worker.
(b) Day light should be reinforced with artificial lights, depending upon the nature of work.
(c) The environment should be well-ventilated and comfortable.
(d) Dust and fume collectors should preferably be attached with the equipments giving rise
to
them.
(e) Glares and reflections coming from glazed and polished surfaces should be avoided.
(f) For better perception, different parts or sub-systems of equipment should be coloured
suitably. Colours also add to the sense of pleasure.
(g) Excessive contrast, owing of colour or badly located windows, etc., should be eluded.
(h) Noise, no doubt distracts the attention (thoughts, mind) but if it is slow and continuous,
workers become habituated to it. When the noise is high pitched, intermittent or sudden, it
is more dangerous and needs to be dampened by isolating the place of noise and through
the use of sound absorbing materials.
2. Work place layout
Design considerations
(a) Materials and tools should be available at their predetermined places and close to the
worker.
(b) Tools and materials should preferably be located in the order in which they will be
used.
(c) The supply of materials or parts, if similar work is to be done by each hand, should be
duplicated. That is materials or parts to be assembled by right hand should be kept on right
hand side and those to be assembled by the left hand should be kept on left hand side.
(d) Gravity should be employed, wherever possible, to make raw materials reach the
operator
and to deliver material at its destination (e.g., dropping material through a chute).
(e) Height of the chair and work bench should be arranged in a way that permits
comfortable
work posture. To ensure this
• Height of the chair should be such that top of the work table is about 50 mm below
the
elbow level of the operator.
• Height of the table should be such that worker can work in both standing and
sitting
positions.
• Flat foot rests should be provided for sitting workers.
• Figure 1.12 shows the situation with respect to bench heights and seat heights.
• The height and back of the chair should be adjustable.
• Display panel should be at right angles to the line or sight of the operator.
(f) An instrument with a pointer should be employed for check readings where as for
quantitative readings, digital type of instrument should be preferred.
(g) Hand tools should be possible to be picked up with least disturbance or rhythm and
symmetry
of movements.
(h) Foot pedals should be used, wherever possible, for clamping declamping and for
disposal
of finished work.
(i) Handles, levers and foot pedals should be possible to be operated without changing
body
position.
(j) Work place must be properly illuminated and should be free from glare to avoid eye
strain.
(k) Work place should be free from the presence of disagreeable elements like heat,
smoke,
Suggested work place layout
Figure 1.13 shows a work place layout with different areas and typical dimensions. It
shows the
left hand covering the maximum working area and the right hand covering the normal working
area.
Maximum working area
It is accessible with full arm stretch. Figure 1.14 shows work place layout for assembling
small component parts. A-1 is the actual working area and the place of assembly (POA) where
four component parts
P-1, P-2, P-3, and P-4 are assembled together. Bins containing P-1, P-2, P-3, and P-4 and
commonly
employed tools (CET) (like screw driver, plier, etc.) lie in the normal working area A-2.
ORT
Occasionally required Tools (ORT) (hammers etc.) lie in the maximum working area A-
3. After
the assembly has been made at POA, it is dropped into the cut portion in the work table – PDA
(Place for dropping assemblies) from where the assembly is delivered at its destination with the
help of a conveyer. This work place arrangement satisfies most of the principles of motion
economy.
3. Other areas
Other areas include studies related to fatigue, losses caused due to fatigue, rest pauses,
amount of
energy consumed, shift work and age considerations.
6.3 SCOPE AND OBJECTIVES OF WORK STUDY Work Study - An Overview
Though the work study is originally developed for improving the productivity and efficiency of the production, the technique is applicable widely. Industrialists and educationalists have recugnised its significance and have been applying in every field even in transport offices, sales and distribution and many more service organisations. Work study finds a place in every field for improvement of the method. Further it is useful to any field and at any point of time anywhere for exhibiting the excellence.
Basic objectives of the work study are
(a) Improvement in working process.
(b) Standardisation of procedures.
(c) Effective utilisation of resources like men, materials, machine, money and time.
(d) Efficient and fast material handling.
(e) Decision on fair day wage.
(f) Enabling a good decision making on manpower requirements, etc.
(g) Better work culture, working environment by ergonomic studies.
(h) To provide an effective control of system.
(i) To make the method of doing operation easy.
(j) To economise the movements i.e. motion economy.
(k) To increase the productivity by eliminating the unnecessary work elements.
(1) To make an effective layout of work place so as to reduce the number of movements.
SAQ 2
6.4 WORK STUDY - AN OVERVIEW
Work study is the investigation, by means of consistent system to attain the best possible use of available men, machine, materials, money and time. Total concept of the work study is concentrated upon the answers of following two questions.
(a) How should a job be done? How a job should be done?
(b) How much time a job should take for completion?
The answer for the first question is method study while the answer of the second question is time study and work measurement. In fact method study and the time study are not to be treated as two different parts of the work study and are very much inter-linked. However for the ease of understanding, the work study is often classified into two parts as time study and method study as shown in Figure 6.1. Time study with its extension is known as work measurement whereas method study is sub-divided into
\Vork System Design two groups as motion study and micro motion study. The motion study has extended to the motion eaonomics while micro motion study has led a way to ergonomics.
Tlme Study I I ~ e t h o d study I
Work Management
6.4.1 Time Study
Time study is the brain child of F. W. Taylor, whose philosophy was mainly concentrated to develop a scientific method to any human problem. This is attained by selecting a worker for each particular task and then training him soundly, essentially by developing cooperation between workers and the management. Of course, the division of work, the responsibility, the authority and the accountability are the distinct features to be observed in cultivating this work culture. Taylor's approach was further developed by his students Barth and Merrick and is summarised as follows :
(a) Split up a work into small activities called elemental movements or simply elements.
(b) Eliminate all unnecessary elements.
(c) Assign time to each elemental motion accurately with the help of stop watch or standards.
(d) Classify and describe each elemental motion and its time carefully for future reference.
(e) Add an allowance to actual time to cover the time delays due to known or forecasted or unforeseen reasons.
(f) Standardise the tools and working conditions with more emphasis laid on method improvement.
Taylor summarised all these in three simple words viz. Definite task, Definite time and Definite method. His study was directed towards the specialisation and standardisation. Time smdy has also given rise to a firm scientific and calculative opinion on remuneration system.
The remuneration system as per time study sticks on to the following points :
(a) Assign each worker a clearly defined task with definite time.
(b) Provide each worker with such standard conditions and appliances as will enable him to accomplish the task with certainty.
(c) Remunerate each worker with large pay when he accomplishes his task.
(d) Make sure that when a workman fails, he is the loser thereby.
Thus time study IS basically a work measurement technique and is defined as follows (according to I. L. 0.).
Time study is a work measurement technique for recording the times and rate of working for the elements of a specified job carried out under specified conditions and for nnalysing the data so as to obtain defined level of the performance.
6.4.2 Method Study Method study is a systematic and scientific evaluation of existing and proposed plans and perfomlance of a work and evaluation of improvement through analytical process of critical examination. This is a broad investigation for improvement of total department, layout of machines, equipment, flow of materials and movement of men. This will be discussed in Unit 7. Method study has two levels of its application. These are :
(a) Motion study, and
Motion Study
This is more detailed investigation of individual operation or operator and layout of materials, parts or tools around a working bench or machine, use of jigs, fixtures and consumables to perform the job effectively. The study of environment, body postures, gestures, the noise level, the temperature, the pressure, the humidity around the work place are the major concerns of motion study which are now known as 'ergonomics'.
Micro-motion Study
This is the most detailed investigation of the movements of hands, arms, limbs, legs, head, etc. while performing the job. Motion pictures, cameras, filmed records, etc. are a few tools used to study the micro-motions of a specified job.
The pioneering developments of Frank Gilbreth and his wife Lillian Gilbreth through process charts, Therbligs, cycle graphs, chrono-cycle graphs, etc. are ever new techniques applied world-wide in micro motion study.
Industrial engineers believe that Method study stands on three pillars, namely the Economic factors, Technical factors and Human factors. Why these factors are called as the pillars? The answer for this question is not beyond the thinking of the reader. Yes, it has to take care of these three factors in the equal proportions. Method study is represented and defined as follows :
Method study is analysing
Development
The basic procedure of method study consists of the following steps :
(a) Define the problem and select the work to be taken for the study.
(b) Record all the relevant facts about present method.
(c) Examine the facts critically and impartially.
(d) Develop the most practical, economical and effective method which will satisfy the three pillars viz. economical, technical and human factors.
(e) Define the new and improved method so that the method can be identified 1 . 1
Work System Design Method study can be applied to layout, working conditions, movements, quality standards, designs, tools and equipment and material handling which may be detected to achieve the improvements either in short term or in long term benefits.
Thus method study is defined as follows (according to I. L. 0.).
The systematic recording and critical examination of existing and proposed ways of doing a work as a means of developing and applying easier and effective method and thereby reducing the cost.
The readers may always get a doubt that out of method study and time study, which one starts first? After understanding the two terms -time study and method study - this question often confuses the readers since the work measurement (time study) is done for a definite method and a definite task. But based on the time study an industrial engineer can critically examine the effectiveness of the method. Because work measurement has to be based on a standardised method it would be obviously absurd to standardise or to find the best method.
The time taken for the job is important in method study and hence time study seldom precedes while finding improved method. While for a new job the method study should succeed the time study to standardise it. All the techniques of work study are in fact inter-related and any separation is only for convenience of decision. It is as same as questioning "Is seed first or the tree?' The discussion is endless in fillding the exact answer. Hence the readers are once again clarified that method study and time study are two different parts of work study.
Activity 2
Write some slogans on work study, method study, motion study and micro-motion study and exhibit in your organisation.
SAQ 3
(b) Define and explain the following :
(i) Time Study
(ii) Method Study
(iii) Motion Study
(iv) Micro-motion Study
6.5 DEFINITION OF WORK STUDY
Afier getting an overview of the work study you would have already arrived to clear cut definition of work study. According to British Standard Institution (BSI) work study is defined as follows :
"Work study is generic term for those techniques particzllarly method study and work measurement, which are used in all its contexts and which leads systematically to the investigation o f all the factors which affect the efficiency and economy of situation being reviewed."
In simple words "It is a terin embraces the techniques of method study and work measurement which are employed to ensure the better possible use of human and material resources in carrying out a specific task." And in another way work study can also be defined as "the systematic. objective, critical and imaginative examination of all factors governing the operational efficiency of any specified activity in order to effect improvement."
6.6 NEED FOR WORK STUDY
Many concepts have been developed in the recent past for improvement such as Value Engineering, Waste Elimination, Kaizen, Zero Defects, etc. Yet, work study did not lose its identity and has got its own charm and significant role in continuous improvement plans of the job due to its specific characteristics and features. The strong base, supportive experimentation and immediate results are making it ever new process. Further it is uniting the people at all levels like owner, managers, foremen and workers by clubbing the various resources like time, machine, material, men and method.
The work study is a wonderful tool, which can inter-link any two resources like time and method, men and machine, man and material, etc. The industrialists and industrial engineers have realised the effective working of work study and recognised ease in it. On the other side, they are also identifying need for improving the productivity in the competitive world with growing demand. To meet this demand there are only two options - first is to increase the volume or capacity of production by enhancing their machinery or equipment orland men orland material. The second option is to increase the productivity and thereby its capacity by eliminating waste. The former method is costly and cumbersome and involves decision making at many stages. Particularly it is mostly advisable to capital intensive industries. While the latter one is applicable to all the sectors and to all the situations as it is easy and less expensive.
Hence, the managers prefer to conduct the work study on their jobs. Since globalisation is demanding the standardisation and liberalisation in extending the competitive spirit, the present world has understood the need for work study on every elemental movement of operation of their work or task.
Summarily, we can say that work study will be needful to the organisation as shown in Figure 6.2, it takes care o f :
Figure 6.2 : Different Aspects of Work Study
Economic Aspects
Such as cost reduction, increased production, variety of products in monetary terms.
Work Study - An Oven'iew
Such as improvement in process, method refinement, elimination of waste elements or movements, technology upgradation, standardisation, product compactness, equipment renovation, product development, etc.
Human Aspects
For example, ease of operation, comfort to producer, customer or user, safety to human beings, machinery and environment.
SAQ 4
(a) Define work study. Explain its need in Indian industrial scenario.
(b) Give the basic aspects that a work study takes care of.
6.7 ADVANTAGES OF WORK STUDY
Work study has numerous advantages. The merits which have gained the prominence are listed below.
Cost Reduction
The sltudy results in lowering of cost of manufacturing as it eliminates unnecessary movements in work or job or motions.
Productivity Improvement
It enhances the efficiency of the production and hence increases the productivity.
Profitability
It raises the profitability without rais'ing the sales price of the product. For example, a product manufactured at Rs. 100 and sold at Rs. 120 will give a profit of Rs. 20, which is 20%. If the same is able to be manufactured at Rs. 80 by using work study and is sold at Rs. I00 gives a profit of Rs. 20 but it is 25%. And if it sold at Rs. 120 imagine the profitability, which is about 50%. This is definitely better than raising the sales price to Rs. 150 (to get a profit of 50%) and making uncertain or risky sale ability, which takes the product away from the common customer's reach.
Standardisation
The work study standardises the work by which the employees get job security and the customer finds reliability and interchangeability. The target or task performance of the worker will be his weapon to safeguard his job while customers get delighted by getting a standard product.
Easier Work
The purpose of the work study is fulfilled if the job is made easier even though it couldn't reduce the cost nor increase the production. Because the ease in doing the job will automatically raise the productivity by reducing the fatigue in the employee.
Fair Day Wage
As the work is timed and based on this, the target is fixed, the operator gets a "fair day wage" as explained in Taylor's approach. This not only regulates the employee but also provides the employer a good control over the workmen. So also it builds up a fair relationship between the employer and employee.
Bctter Working Conditions \\'ark Study - An Overview
Work study provides good working conditions by which the worker would love to work in the environment. It also makes the work place clean. neat and tidy and thus brings out a good working culture.
Deterministic Production Schedules
The work study proves the job to be practicable and hence results in exactness in the production by which the production schedule can be met as per the plan. This makes the producer to satisfy the customer by meeting the delivery schedules accurately.
Activity 3 List out the areas in your organisation (or the organisation with which you are most familiar), where conducting the work study is needed. Also give reasons why you feel that there is a need.
SAQ 5
(a) Enumerate the advantages of work study.
(b) "Work study is powerful tool for management while it is a boon for workers." Critically appreciate the statement.
6.8 PRODUCTIVITY AND WORK STUDY
In any country, the satisfactory living standard depends on national productivity. The degree of availability of different matters like food, clothing, shelter, security and essential services to the country depends on the productivity in a macro level but when seen in a micro level, a productivity of each of the above things is a challenging task to the country. As the summation of all these micro development builds up the macro level development, the responsibility of developing the productivity at micro level has come on to shoulders of every citizen in general and industrial engineers in particular. This necessitates the industrial engineers to understand the concept of productivity and how best it could be improved through the work study.
6.8.1 Concept of Productivity
The term productivity has been used for the first time in 1776 by Dr. Quensney, a great physiocrat but after so many years, i.e. at the end of 19th century it was understood as the factor to produce.
Drucker defined productivity as "The balance between all factors of production that will give the maximum output for the slnallest effort."
Some More Definitions
Productivity in its broadest sense is the quantitative relationship between what is produced and the resources, which are used.
Productivity may be defined as the ratio between the output and input.
Work System Design The concept ofproductivity has been termed in variozis ways such as attitude of mind; continuous efforts towards progress; the certainry of being able to do better tomorrow than today. Some people called the productivity as the personal efJiciency and to some others the output of an aggregate collection of resources.
Mathematically, the productivity can be represented as the ratio of output to input.
Output of the system (0) Productivity (P) =
Input to the system (I)
6.8.2 Production and Productivity
These terms have already been explained in Unit 5, and are refreshed here to facilitate a quick reference.
We know that the production or the output being the result of coordinated effort and the productivity (efficiency) is the function of efficiencies of all the specialised units whose coordinated efforts lead to production. Hence, it is clear that the productivity (P) of a system is the function of efficiencies of many subsystems (P,).
Productivity (P) = f (P,)
All the subsystems together lead to productivity of the whole system.
So production is the conversion process of the raw materials into useful products or items by using human efforts and time, materials and machinery in easier, economic and safer methods in a minimum possible time.
Increase in productivity is the contemporary of increase in output, also increase in input or resources. It may be likely that the increase in output causes the productivity to remain constant, decrease or increase. It depends upon mainly the effective utilisation of resources like materials, machines, methods, men. etc. so as to achieve the maximum productivity, where the work study plays a key role.
6.8.3 Role of Work Study
As explained above, Productivity of a system is the function of production, all individual subsystems and production depends on the output and input characteristics. The increased output results in more production, but it need not be high productivity. The increase in productivity is resulted by one of the following ways :
(a) Output is increased when input is constant.
(b) Same output or result is attained by reducing input (eliminating the waste).
(c) Output is raised while input or resources are reduced (eliminate waste).
Work study shows the way to achieve the above so as to increase the productivity because it basically aims in :
(a) Increasing output.
(b) Doing the work faster.
(c) Easing the work and hence enabling the workman to work more.
(d) Eliminating waste elements of motions and time.
Thus the work study plays a vital role in achieving the high productivity.
SAQ 6
How is work study related to productivity? Establish the relation.
Wnrk Systen~ Ilesign 7.2 OBJECTIVES OF METHOD STUDY
The method study is conducted with a main focus on the following objectives :
(a) To bring improvement in process or procedure.
(b) To bring improvement in work place, workshop, working environment, layouts, etc.
(c) To bring economy in use of human effort and thereby enhance the human efficiency and productivity.
(d) To reduce unnecessary fatigue.
(e) To increase human comfort while doing work.
( 0 To set-up better physical working conditions.
(g) To explore the ways for effective use of materials, tools machine, men and their movements.
SAQ 1
Why is method study needed?
7.3 PROCEDURE OF METHOD STUDY
Different authors gave the method study procedure in slightly different steps. First of all, I L 0 proposed a baslic procedure consisting of five steps as Select, Record, Examine, Develop and Define. Some authors have added few more steps to this with designing, installation, implementation, maintaining, etc. However, the standard procedure consists of the following six steps :
(a) Select
(b) Record
(c) Examine
(d) Develop
(e) Install
( 0 Maintain
These are briefed out in the following paragraphs. (The readers may remember these with an acronym SREDIM, made of first letters of the words, which means 'to stab'.)
7.3.1 Select
Selection of problem is not as simple as one can think of. The problem identification involves a deep understanding into the methods and procedures followed to produce the product. However, industrial engineers have been provided with certain guidelines in selecting the problem and the tools for problem solving. These are given below :
The Problem
The problem is selected from the area or process where least yield is resulting or where loss of output is felt. The problem must be selected in such a way that it should be possible to solve and would get a feasible solution. A problem, which
cannot be reduced to any solution and impracticable, should not be selected. For example, trying to find a generator which can start without external power and without any power loss is impossible.
Also the problem selected should be as small as possible. Selection of a problem of large volume, which involves many people, can only become a mess. The problem selected should be defined precisely and distinctly.
The Man
Often, to solve the problem, the industrial engineer requires selecting an operator who can perform the modified method for defining the task and time study. The operator selected should be representative, i.e. the one who is selected should resemble to the group and normal in all respects such as efficiency, behaviour, skill, knowledge, etc. He should neither be highly skilled nor be unskilled. He should be neither highly efficient nor very low efficient and so on. He should have known all the parameters and phases of work. He must have willingness to work. He should be explained about the task, related job knowledge and concepts. He should be able to convince his co-workers with his achievements.
The Machine
Like the selection of man, the engineer conducting method study, needs to select a ~iiachine also to take a decision on target fixation. The machine so selected should neither be new nor be old but in good operating conditions. It is better if the study is conducted on several machines to avoid unilateral decisions. The machines should be accurate and should repetitively give some results (precision) with a good process capability.
The Material
Material with good quality and specified properties should be provided.
The Working Conditions
The method study should be conducted at various combinations of working conditions ranging within ergonomically specified ranges. Also the experiments should be carried out at different times of a working day and different days of a month and at different seasons if required before standardising the methods.
7.3.2 Record After selecting a particular task for study, it is essential to record the relevant facts regarding different processes or procedures, inspection parameters, transport constraints and various basic resource requirements and availabilities. An effective recording methods, charts and diagrams can help the decision quickly, easily, correctly and timely. Various charts available and in common use are explained in two categories as Type-A and Type-B as follows :
Charts
Type-A : These charts show the process required by the task as per their sequence.
I Out line process chart
Flow process chart-man type
Flow process chart-material type
Flow process chart-machine type
I Two handed process chart
I Type-B : These charts show the process on time scale according to their sequence.
i I
\lethod Study
Apart from the above charts, there are a few diagrams seldo~ii used in work-study. They are :
Diagrams : Flow diagram
String diagram
Cycle graph
Chronocycle graph
Travel chart
Rel chart
A brief explanation of these charts is given at the end of this unit.
7.3.3 Examine
After proper recording of the data, it is now important to examine these facts critically. All if s and but's could be brainstormed and some conclusions are to be drawn. These conclusions should be evaluated thoroughly from all the angles to choose best alternative. The pros and cons of each alternative should be written and a comparison chart is to be prepared if there are more than one good alternative by choosing suitable parameters for rating.
7.3.4 Develop
Develop the most efficient alternative with high degree of accuracy. Measurements should be made impartially and see that there will not be any human errors while developing the method. It is very important to consider Economic, Technical and Human aspects during developing activity. The method should be clearly defined after developing it. Also the amount ofjob involved and standard should be calculated.
7.3.5 Install
Prepare an implementation plan and install the new method. Choose a suitable period of time to watch the progress and efficiency of the method. It has been often reported by the industrial engineers about the resistance from employees to the new method. No doubt, the static friction is definitely more than dynamic friction. So also the human reactions for any new thing. The records and comparison charts will certainly become the useful tools to convince and authenticate the new method.
7.3.6 Maintain
The final step of method study is in fact the most difficult part, to implement and maintain. 'The progress is to be recorded time to time and evaluated in suitable intervals. After a sufficient number of production runs and test readings, it is to be declared or standardised. However. it is essential to gain the acceptance from various supervisors, workers involved (sometimes even from union) and management and the workers orland supervisors are to be maintained properly to maintain the new method thereafter.
Activity 1
Suppose you are the manager of a fast food centre. Conduct method study on 'toasting of bread'. Record your study as follows :
(a) Selection : Madmachine or equipmentlmaterial, etc.
\\'ark System Design Objectives
After studying this unit, you should be able to t
understand the time study and conduct a time study,
rate a job and a worker doing certain job,
calculate the basic time, normal time and standard time of a job or element, and
fix the target for job.
8.2 WORK MEASUREMENT AND TIME STUDY
Work measurement is very difficult owing to diversified set of reasons. Perhaps the measurement of human factors is the most difficult factors of all. The human measurement particularly with a balance between work content and labour time is beyond the scope of scientific methods due to various physiological factors such as frustrations, monotony, boredom, anxiety, willingness to work, skill, will power, confidence, attitude and many more. Apart from these there will be the influence of physical and environmental factors like temperature, dust, noise, vibrations, pressure, humidity, etc. keeping all these in normal or acceptable conditions some methods have already been laid down for measurement of any type of work. The work measurement is generally followed by method study by which a clearly defined and developed method is laid down.
All that credit goes to the pioneering work of Fredrick Winslow Taylor for his methods of work measurement and time study. He suggests to split the activity into elements and assign the time to it by repeated experimentation. Thus time study provides a reliable data for establishing consistent standard performance and elimination of the ineffective time from the production cycle time.
As Defined
Work measurement is the application of techniques designed to establish the time for a qualzfied Worker to carry out a specrfied job at a defined performance.
and,
Time study is a work measurement technique for recording the times and rate of working for the elements of a speczjiedjob carried out under spec~fied conditions/and for carrying out the job at a defined level of the performance.
(Definition according to ILO)
8.3 TIME STUDY EQUIPMENT
The following equipments commonly are used for conducting time study.
(a) Stopwatch : to record time
(b) Time study board : for affixing time study forms
(c) Time study forms : affixing on board (formats are shown)
(d) Pencils and erasers : for entering values
(e) Calculator : calculating equipment
( i ) Spring balance
S : Slide for stopping and starting the movement
W : Winding knob; this returns both hands of watch to zero, when being pressed
Figure 8.1 : Stop Watch
Time Study Sheet
mote : Work Place layout is to be di-awn on the backside of time study sheet)
............................. Department : .......................... Department code : .............................. .............................. Operator : Employment No. :
..................................... Operation : ........................... Drawing No. :
Checked by : ........................... Date of Checking : ............................ Approved by : ......................... Date of Approval : .............................
Time Study - Work Measurement
Work System Design Cycle Time Study Sheet
(Note : Work place layout is to be drawn on the backside of cycle time study sheet)
Department : .......................... Department code : ............................. Operat'or : .............................. Employment No. : .............................. Operation : ........................... Drawing No. : ..................................... Machine : .............................. Machine No. : ..................................... Product : ................................. Part No. : ............................................ Material : ................................ Tools/Guages : ................................... Clock No. : ............................. Srudy No. : ........................................ Study conducted by : .............. Date of Study : ................................... Checked by : ........................... Date of Checking : ............................ Approved by : ......................... Date of Approval : .............................
Steps in conducting time study :
Element i:. b; ~escription
Record all the necessary information about the job such as product information (name of the product, material, quantity, quality requirements), process information (location of work place, process description, tooling, jigs and fixtures, layout, speeds and feeds, settings, rate of productions), information about operator (name, competence, skill, education, experience, etc.), information regarding working conditions (temperature, pressure, humidity, economical factors, human factors, lighting, etc.
I I I
Reading on Stopwatch (Observed Time)
Record the method by breaking down the operation into elements to ensure most effective method and sequence of the motions.
-------
Taken '
1 2 3 4 5 6 7 8 9 1 0
Record the skill and competence of the operator to ensure that 'qualified' worker is allowed to work that is to be timed. A 'qualified worker' is one who is neither very skilled nor unskilled but an average; neither highly experienced nor inexperienced, and so on, so that the measurement is made at any normal level.
_1
Step 4
Record the time for each element of the operation with the help of stopwatch or by any other time measuring device or formula. The process of time taking of the same element may be repeatedly for pre-determined no. of times and the rate of the worker is to be compared with preconceived concept of standard rating.
Step 5
Compute the basic time for each element by taking the average and then compute the normal time with the formula;
Normal time = Basic time x Rating factor
Step 6
Determine the allowances to be added to the normal time to determine the standard time by using the formula;
Standard time =Normal time x Allowances Factor 100 - allowance in %
I Recording Necessary Information
(ii) Name of the part and number according to drawing
(iii) Material
(iv) Quality
(b) Information regarding the process :
(i) Location of work place
(ii) Sequence of operations
(iv) Tooling
(vi) Work place layout
(ii) Education
(iii) Experience
(i) Temperature - minimum and maximum
(ii) Humidity
Breaking the Job into Elements
(a) Examine the method employed and carry out the operation to ensure whether it is efficient method.
(b) Describe the complete process after checking
Time Study - Work Measurement
\\ orli Sysccr11 Design (c) Break the operation into elements. While breaking the job into elements. only one work cycle should be taken into account. An element is defined as "a distinct part of the specified job selected for convenience of observation, measurement and analysis". For example: "turning operation" on a lathe machine, the elements are like this
(i) Job fixing in the 3 or 4 Jaw Chuck.
(ii) Tool settinglcentering,
(iv) Removing the job from chuck.
(d) The selection of elements should fulfill the following characteristics :
(i) Duration of every element should be as short as possible but, it should be able to be timed accurately.
(ii) Man controlled elements (handling time, should be separated from machine controlled elements (machining time).
(iii) Repetitive and non-repetitive elements must be clearly demarcated.
(iv) There should be a clear distinction between the effective (productive) and ineffective (non-productive) time elements.
(v) The constant elements, which are independent of size, shape, weight, etc. of work should be separated from the variable elements.
Timing each Element
Each element is timed by using a stopwatch either in conti~iuous method (cu~nulative timing) or snapback method (fly back timing). Altliough both methods are equally efficient in working, there is a chance of loss of time in fly back timing while resetting it to zero. Hence the former is supposed to be more accurate while the latter reduces clerical work and hence the costs. However, the element is performed several times and the time is recorded. The average of these timings is then c,:lculated to find the normal time.
Let us now take a numerical example to demonstrate this :
A cycle consisting of five elements in a working cycle has yielded the following timings on the stopwatch
Element Number Stopwatch Reading in Element Time I 100"' of 4 Minute 1 (in 100'" of a Minute) 1
Example 8.1
A job has been sub-divided into five elements. The time for each element and respective rating are given below :
1 Element Number I Observed Time I Rating Factor '10 I
Calculate the normal time and standard time for each element and for the job if the alIowance is 15%.
Solution
80 = 0.7 x - = 0.56 min.
100
For Element 2
100
= 0.94 min. 100 - 15
100
= 1.835 min. 100-15
For Element 4
100
For Element 5
100
= 1.41 min 100 - 15
SAQ 1 L
(a) What do you understand by time study and work measurement?
(b) Explain the systematic procedure of time study.
(c) Describe the equipment used for conducting time study. I
(d) A job has been sub-divided into 4 elements. The time for each element and t i respective rating are given below :
Time Study - Work Measurement
Calculate the normal time and standard time for each element and for the job if the allowance is 5%.
Rating Factor %
1 .O
(e) The observed time for an element is 2 minutes. I'hr rating factor is 80%. If standard time is 1.76, how much allowance is given for the element?
Activity 1
(a) Toasting of a bread.
.........................................................................................................................
(d) Thread cutting operation on lathe.
.........................................................................................................................
8.4 PERFORMANCE RATING
Tlze Society ofAdvancement of Managemen1 (SAIM) nationul committee defines the performance rating as "the process during which the time study engineer compares the performance of the operator under observation ~ijith the observer S own concept of proper fnormal) performaizce. It can also be considered as the efficiency of the worker.
Observed performance The Performance Rating or Efficiencty = x I00
Normal perfcrmance
' lhe time taken for a job varies from person to person attributed to various reasons such as environme17tal factors and ;~uman factors discussed in mqtion study (Unit 10 of this block). Sometimes. we come across some complaints such as the worker is intentionally doing delay or the observer's judgement is prejudiced. To overcome such disputes, the normal rating is compared with performance rating to standardise the time and thence fix up the target of an element or job.
V;rnuus systcms of performance rating are as follows .
(a) Westinghouse system of rating
(b) Synthet~c rating
I jc) Physiological evaluation of performance level.
8.4.1 Westinghouse System of Rating This system is based on four factors :
(a) Skill
(c) Condition
(d) Consistency
Various ratings are tabulated in the Table 8.1 as glven by Westinghouse. The actuals are conlpared and suited with one of the ratings in each of the above four factors and
t summed up for finding total rating. This is added (or subtracted) to unity to find the rating factor. On multiplyiilg with the actual (Observed) time, we get Normal or Basic time. The standard time is then calculated by adding allowances to the normal time. This is illustrated through the numerical problems given below.
Table 8.1 : Westinghouse Performance Rating Table
Surnmarised formula for calculation :
Westinghouse rating = Sum of ratings, i.e. rating of (Skill + Effort + Conditions + Consistency) as given in Westinghouse tables.
Rating Factor = 1 f Westinghouse Rating
Normal Time = Observed time x Rating factor
Standard Time = Normal Time x 100
(100 - Total allowances in percentage)
Example 8.2
The observed time for an element was one minute and the rating were found to be as follows :
Skill Fair EI
Effort Excessive Al
Condition : Good C
Consistencv : Excellent B
Work Tirtlc Study - ~Mrusuretnenl
Sj.s te~n Design Determine the r,ormal time or basic time for the element undcr observation. (Refer Westinghouse performance rating table). Also tind the standard time @ 20% allowance.
From the Performance Rating tables of Westinghouse system: 1 skill 1 Fair El 0.04 1 -- !
Effort Excessive A, 1 0.13
1 Condition I Good c j 0.02 ,
I I Ovesall (Total) Rating 0 . 2 2 I
i.e. positive rating by + 0.22 over unity = I + 0.22 = I .22
Normal Time = Observed Time x Rating Factor
Standard Time = 1.22 x = 1.525 rniri.
Find the Normal Time and Standarc! Time for an element. which has the following ratings in Westinghouse system, and observed tiwe is 1.2 minute.
I Consistency Poor I
Avcragc Averagc 1
I
Condition
Consistency
i.e. negative rating by - 0.07 under unity = 1 - 0.07 = 0.93
:. Nor~nal Time = Observed Time x Rating Factor
0.00
A.ierage
Average
- 0.03
- 0.04
= 1.24 min. 100 - 10
SAQ 2
(a) Find the standard time for an element of one minute observed as average in all the factors of Westinghouse system and 15% allowances are given.
(b) The observed time for an element was one minute and the rating were found to be as follows : Wor
i Skill I super A , i i c "fort
1 Condition I I
Fair
Ideal
Consistency
1 Observation No. 1 1 1 2 1 3 1 4 1 5 1 6 1
1 3 2 / A !
I Ef'ort I ( Exccsrive
1 Time in Minutes 0.2 1 0.3 0.4 1 0.6 1 0.4 1 0.2 )
Average
/ Condition
Determine the normal time or basic time for the element under observation. (Refer Westinghouse performance rating table).
D I
Deterln~ne the normal time or basic time for the element under observation. (Westinghouse perforinance rating table will be provided).
(c) Calculate normal time for an element of 2 minutes with skill, effort. condition and consistency as 0.11, 0.05, - 0.03 and 0.00, respectively.
(d) The following observations of actual time taken by worker for doing a job repeatedly were taken by a time study observer. The rating were found to be as follows :
Excellent
[Hint : Take actual time of an average time of the six observations.]
r
Skill
8.4.2 Synthetic Rating
Good CI 1
This system of rating was introduced by Morrow. The time study observer records the actual time of performance for the element as done in the previous method. Performance times for such elements have been standardised, which are known as "Predetermined Motion Time Standard Values" or 'PMTS Values7. The PMT value for the elements from such tables are noteci. The ratio of Predetermined Motion Time Standard value of the element (taken from tables) to Average Actual Time (Observed Time) for the same element gives the Rating Factor.
Summarily this is expressed as
where, R = Performance Rating Factor,
P = Predetermined Motion Time Standard value for the element in minutes (from tables), and
A = Average Actual Time (Observed) for the same element in minutes.
The average actual time for 6 elements of a task were measured and tabulated below. The Predetermined Motion Time for two elements is also given. Calculate the performance rating factor. Also find the normal times for all the elements on the basis of average rating.
P
Element No. 1 2. 3 4 5 6
Average Actual Time (A) 0.5 0.6 0.5 0.4 0.3 0.6 I Predetermined I Motion Time (P) 1 0 . 4 5 1 I 1 0 . 4 6 1 i I ,
Solution
P 30.45) Performance Rating ( R ) = - = j - i x 100 = 90% for first element.
A i 0.5 )
Performance Rating ( R ) = = !El x 100 = 1 1 5% for fourth element. A \ 0.4 )
Average R = ( 1 15 + 90)
= 102.5'/6 2
(Actual Time x Average Rating)
8.4.3 Objective Rating It was proposed by M.E. Mundel and is carried out in two steps.
Step 1
The speed or pace of the operator is rated against an objective pace standard. This objective pace standard is same for all the jobs irrespective of the job difficulty and its limiting effect on pace. Mundel uses the tenn 'Base Time' for this time rated against pace.
B = P x T
where, B = Base Time,
P = Rated Pace, and
Step 2
Now, the numerical obtained in step 1 is appraised by an adjustment factor. which Mundel calls job difficulty factor or job complexity or secondary adjustment.
Thus, it is expressed as
Normal Time ( N T ) = B x M
where, B = Base time (P x T), and
M = Job Difficulty Factor.
After calculating normal time, standard time can be found by usual ~nethod a s
Standard Time (ST) = Normal Time (NT) + Allowances (Aj
Job difficulty is measured based on six factors as given in Table 8.2.
Table 8.2 : Job Difficulty Factors
Adjustment
Amount of body used
Finger used loosely Wrist and Fingers Elbow, wrist and fingers Arm, etc. Trunk. etc. List with leg from floor
2 Food pedals F
Pedal or pedals with fulcrum outside the foot
Hands help each other or alternate
Hands work simultaneously doing the same work
Rough work, mainly feet Modcrate vision Constant but not closed Watchful. fairly close Within 1/64"
Handling N Can be handled roughly requirements O ' Only groll control
P 1 Must be controlled but may / be squeezed
(2 Handle carefully R / Fragile
Weight Identified by the actual weight for resistance
Summary
Normal Time = Base Time x Secondary Adjustment (B.M) = PMT
Standard Time = N + A = PMT + A
Example 8.5
The observed time for an element is 1.2 minutes. The pace rating for the element is 120% and job difficulty is found to be 30%. Find Normal Time o f the element. Also find standard Time a t an allowance o f 10%.
Solution
100
100 100
= 2.08 min. I00 - 10
\\'arlc Syhtc~n Design Example 8.6
An Element is observed to be carried out in 0.8 minutes. Given pace rating is 110% and the secondary adjustment by 20'96, find the time on any tBir day. If* 0.2 minute per element is given as allowance, what is the standard time taken for 20 repeated actions?
Solution
100
100
= 1.32 min. 100 - 20
Time taken for 20 actions = 20 x 1.32 = 26.4 minutes.
SAQ 3
(a) The observed time for an element is 0.4 minute and the pace rating is 90% and the sum of all secondary adjustments amount to 20%. Find the normal time.
(b) The observed time of an element is 0.7 minute and the pace rate is 80%. If the normal time is decided as 0.73 minute, find what percent of adjustment is added towards job difficulty.
8.4.4 Skill and Effort Rating
This system was introduced by Charles E. Bedaux in 1961 and is also known as Bedaux system. In this system, the observer is supposed to evaluate the work rate or speed of worker's movement and how fast he is performing the motions, but not the movements and skill he is applying. Unlike the other methods Bedaux introduced a unit "B" that represents a standard minute, which is composed of
(a) work component
(b) relawjion component
The p r o ~ d w c k as fol*fows :
(a) Diviele the operation into smallest measurable elements (smallest time is 2 3 seconds).
(b) Time the element with the help of a stopwatch having sixty divisions on its dial.
(c) Take sufficient observations and calculare average time.
(d) Estimate the efficiency of the operator in tenns of B values assuming the average worker must obtain 609 per hour and maximum B value can be 80 B per hour. Thus convert the observed time in terms of B's with reference to a standard of 60 B per hour values.
(e) Allow the relaxation factors as shown in Table 8.3
Table 8.3 : Relaxation Factors
Medium work 1.20 to 1.35 1 Heavy work 1 1 Very heavy work
(9 Now calculate B values for work element by the formula
The number of B's per work element = Observed Time x Speed of work
x Relaxation Allowance/(60 x 60) = (Tb,.,l: 2) where, Th = Observed time in seconds,
V = Speed of work in terms B's, and
Ru = Relaxation allowance.
(g) The sum of all the values of various work elements gives B values per work piece.
(h) Variable time (lost time) and setting are to be recorded regularly and special B values are to be provided accordingly.
(i) Irregular times and disturbance are not to be included.
Cj) Purely machining times where workman is not involved are evaluated separately and added as a method allowance, since only human effort is measured by the Bedaux system.
Example 8.7
For a work element, the observed time was I0 seconds and the speed is found to be 60 points on Bedaux's scale. If the job is a heavy work for which a relaxation allowance is given as 1.20, find the B value for the element.
Solution
60 x 60
=0.2 B
SAQ 4 Find the B value of the work element whose relaxation allowance is 1.25 and the worker with 72 B speed is observed to do in 20 seconds.
8.4.5 Physiological Evaluation of Performance Level
It is known fact that there is a relation between the physical work and the amount of oxygen consumed. It has also been tried out to find the changes in heartbeat for various physical works. This is assumed to be most reliable measure of muscular activity and studies are still goi