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2014-15 •INDUSTRIAL ENGINEERING AND MANAGEMENT UNIT-5
WORK STUDY
Definition, objectives, method study - definition, objectives, steps involved- various types of associated charts-out line process charts, flow process charts, two handed process charts and simo charts- difference between micromotion and memomotion studies.
WORK STUDY:
“Work study is a generic term for those techniques, method study and work measurement which are used in the
examination of human work in all its contexts. And which lead systematically to the investigation of all the
factors which affect the efficiency and economy of the situation being reviewed, in order to effect improvement.”
WORK STUDY
Introduction: Work study is a new name for the techniques usually known as motions and time study. Work
study refers to the method study and work measurement, which are used to examine human work in all its
contexts by systematically into all factors affecting its efficiency and economy to bring forth the desired
improvement.
Objectives of work study:
Scientific and controlled analysis of existing available methods of executing a task.
Measuring performance of mentally and the physically qualified workers, establishing it as standard for
performance measurement.
Optimum utilization of workers, plant, machinery and other resources at minimum cost.
Improved productivity and enhance worker mood.
Increasing efficiency of organization.
Nature & Scope
Work study is a generic term for those techniques, particularly method study and work measurement, which are
used in the examination of human work in all its contexts.
Work study is the study of the work in order to simplify it. In fact, it is an approach in respect of the use of
manpower, material and equipment with a view to eliminating waste in every form. It is extensively used in
agricultural operations, manufacturing, services, and transport and supply industries.
Method study is the systematic recording and critical examination of existing and proposed ways of doing work,
as means of developing and applying easier and more effective methods and reducing costs.
METHOD STUDY: “Method study is the systematic recording and critical examination or existing and
proposed ways or doing work as a means or developing and applying easier and more effective methods and
reducing cost.”
Objectives of method study:
The study is conducted to achieve the following objectives—
1. to bring improvement of work processes and procedures
2. to economize human efforts and to reduce unnecessary fatigue
3. to improve the usage of materials, machines and manpower
4. to develop better physical working condition and environment
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Procedure for method study:
Method study includes the following Steps:
Select – choosing the job or procedure to be studies
Record – collect all the relevant facts about the present or
proposed method.
Examine -critically scrutinizing these facts in an orderly
sequence using the techniques best suited to the purpose
Develop – develop the best possible method
Install -- practice the developed method
Maintain – checking the new standard practice by proper
control procedures and regular routine checks.
Select:
Only such jobs are to be selected that promise substantial
improvement and dividends. Some of the prospective tasks
for the study are those which are holding up certain other
operations – bottleneck tasks which involve a long ‘travel’
of the forms, documents and materials.
After selection of job, it will be a good practice to compile
a list of specifications of the job
Ex: job particulars, who initiated the study, layout etc.
Record:
The current process of doing job has to be recorded. While
doing so, every detail, however small it may be, has to be
identified. Where the process is too long, involving many
stages of production, inspection, the present process of
doing the job is recorded sufficiently, together with all the
relevant information, by using the process chart.
A process chart is a graphic representation of the sequence of events or steps that occur in the work method or
procedure. Classifying them by symbols according to the nature of the event is as follows :
Symbol Meaning
Operation: It involves change in the condition of a product
Transport: Moving something from one location to another
Storage: It occurs when object is kept and protected against
unauthorized removal
D Delay or Temporary storage: A delay occurs to an object when
conditions do not permit the performance of next job
Inspection: Quality and quantity of the product is good or not
Operation cum Inspection: Inspection is taking place during the
production process
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RECORDING TECHINQUES:
Examine:
This is the most important phase of method study. After an activity has been suitably recorded by means of any
method, the recorded events are to be critically examined. The analysis may be based on primary questions like
purpose, place, sequence, person etc.
At the secondary stage, the questions are meant to seek alternatives so as to be able to think out a better, and
finally the best way of accomplishing the task.
Develop:
Based on the recorded data, the alternative methods of doing the same job more effectively are to be identified
and evaluated. From these alternatives, the best one is selected and developed to suit the requirements.
Install:
The new method so developed is to be installed in a phased manner. As part of installation, adequate planning of
schedules and deployment of resources should be taken care of.
Once the method is adopted, the workers have to be retrained, the equipment has to be provided, and the method
has to be tested in order to seek improvement.
Maintain:
It should be ensured that the method is used in the manner intended. Complaints and improvements in
productivity should be registered. Once the new method starts yielding the desired result, it is necessary to
maintain the new method without any change for some time.
VARIOUS TYPES OF ASSOCIATED CHARTS: It can be broadly divided into (A) Macro motion charts and (B) Micro motion charts.
MACRO MOTION CHARTS Macro motion charts are used for macro motion study and
micro motion charts are used for micro motion study.
Macro motion study is one which can be measured through
‘stop watch’ and micro motion study is one which cannot be
measured through stop watch. Graphical method of recording was originated by Gilberth.
In 1947, ASME adopted the following symbol set derived
from Gilbreth's original work as the ASME Standard for
Process Charts:
Operation: to change the physical or chemical characteristics of the material.
Inspection: to check the quality or the quantity of the material.
Move: transporting the material from one place to another.
Delay: when material cannot go to the next activity.
Storage: when the material is kept in a safe location.
Symbol Letter Description
Ο O Operation
Ỻ I Inspection
→ M Move
D D Delay
∇ S Storage
MicroMotion Charts
1.Micro Motion Charts
2.MemoMotion Charts
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1. OPERATION PROCESS CHART (OUTLINE PROCESS CHART): An operation process chart gives the
bird’s eye view of the whole process by recording only the major activities and inspections involved in the
process. Operation process chart uses only two symbols, i.e., operation and inspection.
It considers only main operations and inspection
Surveys and records an over all picture of the process and states only main events sequence- wise.
Out line process chart is the beginning of a detailed analysis
It
helps
in
layout
planni
ng
and
analys
is
2. FLOW PROCESS CHART: Flow process chart gives the sequence of flow of work of a product or any part
of it through the work centre or the department recording the events using appropriate symbols. It is the
amplification of the operation process chart in which operations; inspection, storage, delay and transportation are
represented. However, process charts are of three types:
(a) Material type—Which shows the events that occur to the materials.
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(b) Man type—Activities performed by the man.
(c) Equipment type—How equipment is used.
The flow process chart is useful:
(a) to reduce the distance travelled by men (or materials).
(b) to avoid waiting time and unnecessary delays.
(c) to reduce the cycle time by combining or eliminating operations.
(d) to fix up the sequence of operations.
(e) to relocate the inspection stages.
It is a detailed version of outline process chart and it records all the events . and thus helps in
Sets out sequence of flow(of a procedure or product)
Marks distances travelled and time taken for completing an activity
improving layout and material handling,
Reduces delay
Eliminates unnecessary events
Types of Flow process charts
Man type Flow process chart
Material type Flow process chart
Equipment type Flow process chart
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Flow process chart (material & equipment)
Flow process chart (man)
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3. TWO HANDED PROCESS CHART
• Records activities of the left hand and the right hand (of an operator) as related to each other
• The activities of the two hands can be synchronized by providing a time scale on chart
• It is generally used for repetitive works for short duration
MICRO-MOTION STUDY CHART
Micro-motion study provides a technique for recording and timing an activity. It is a set of techniques intended
to divide the human activities in a groups of movements or micro-motions(called Therbligs) and the study of
such movements helps to find for an operator one best pattern of movements that consumes less time and
requires less effort to accomplish the task. Therbligs were suggested by Frank O. Gilbreth, the founder of motion
study. Micro-motion study was mainly employed for the job analysis.
The Therbligs are micro-motion study involves the following steps:
1. Filming the operation to be studied. 2. Analysis of the data from the film.
The recording of the data through SIMO chart is done as micro motion chart.
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SIMO CHART (Simultaneous motion cycle chart)
Simultaneous motion cycle chart (SIMO chart) is a recording technique for micro-motion study. A SIMO chart is
a chart based on the film analysis, used to record simultaneously on a common time scale the Therbligs or a
group of Therbligs performed by different parts of the body of one or more operators.
It is the micro-motion form of the man type flow process chart. To prepare SIMO chart, an elaborate procedure
and use of expensive equipment are required and this study is justified when the saving resulting from study will
be very high.
The following table lists the Therbligs, along with their mnemonic symbols and standard colors for charting.
Therblig Color Symbol/Icon Therblig Color Symbol/Icon
Search Black
Use Purple
Find Gray
Disassemble
Violet,
Light
Select
Light
Gray
Inspect
Burnt
Orange
Grasp
Lake
Red
Pre-Position Sky Blue
*Hold
Gold
Ochre
Release
Load
Carmine
Red
Transport
Loaded
Green
Unavoidable
Delay
Yellow
Ochre
Transport
Empty
Olive
Green
Avoidable
Delay
Lemon
Yellow
Position Blue
Plan Brown
Assemble
Violet,
Heavy
Rest for
overcoming
fatigue
Orange
Uses of Simo Chart
From the analysis shown about the motions of the two hands (or other body members) involved in doing an operation,
inefficient motion pattern can be identified and any violation of the principle of motion economy can be easily noticed.
The chart, therefore, helps in improving the method of doing an operation so that balanced two-handed actions with
coordinated foot and eye motions can be achieved and ineffective motions can be either reduced or eliminated. The
result is a smoother, more rhythmic work cycle that keeps both delays and operator fatigue to the minimum extent.
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MACROMOTION VS. MICROMOTION STUDIES.
Key difference between Macromotion and Micromotion studies are as under :
Motion studies are performed to eliminate waste. Before any improvement in quality or quantity of
output, any study of operations time, any scheduling of work or balancing of workload or any calculation of
standard time, a study of the current and proposed method is required.
Studies of overall factory flow or process, called macromotion studies, and then additional studies of
detail or operations, called micromotion studies, should be completed for a project.
____________________________________************************______________________
ASSIGNMENT – III ( for UNIT 5 & UNIT 6)
1. What is work study. Explain the method study procedure in detail?
2. What are various Recording Techniques in method study.
(Explain various Process charts with examples)
3. A) 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.
B) 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%
4.A)Define Work Measurement. What are different time study equipments?
B)What are different types of allowances in time study?
