UNIT – 3
3A. PROCESS PLANNING
3A. 1 Process Planning
Process planning is concerned with planning the conversion or
transformation process needed to
convert the materials into finished products. A production process
is a series of manufacturing operations
performed at work stations to achieve the design specifications of
the planned output. A vast number of
different operations and various kinds of equipments and machines
may be required to produce a complex
product (for e.g. an aircraft or a ship). Simpler parts may
require a few operations (for e.g. a bolt and a
nut).
Process planning consists of two parts namely (i) Process design
and (ii) Operations design. Both stages
provide information which is required to effectively utilize
existing equipment and machinery and to
determine what new equipment and machinery would be required.
3A. 2 Process Design
Process planning is concerned with the overall sequences of
operations required to achieve the
product specifications. It specified the type of work stations
that are to be used, the machines and
equipments necessary and the quantities in which each is required.
The sequences of operations in the manufacturing process is
determined by
(a) The nature of the product
(b) The materials used
(c) The quantities being produced and
(d) The existing physical layout of the plant
3A. 3FRAME WORK FOR PROCESS DESIGN
The design of the transformation process requires answers to
several questions given below:
1. What are the characteristics of the product or service being
supplied or offered to customers?
2. What is the expected volume of output?
3. What kinds of equipment or machinery by custom built?
4. What is the cost of equipment and machinery needed?
5. What types of labour skills are available, in what quantities
and at what wages rates?
6. What types of labour skills are available, in what quantities
and at what wage rates?
7. How much money can be spent on the manufacturing process?
8. Should the process be capital intensive on labour intensive?
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9. Should the components or parts be made of purchased? (Make or
buy decisions)
10. How best to handle materials?
3A. 4 PROCESS PLANNING PROCEDURE
a. Selection of Process
For converting raw material to finished goods.
Select the most economical process.
FIGURE : 3.1 FLOW PATTERNS
This selection depends on:
Current Production Commitment
Delivery date
Quantity to be produced
Quality standards
b. Selection of Material
Correct shape and size of the material for reducing the scrap
Right quality, chemical composition as per the given material
specification.
c. Selection of Jigs, Fixtures and Special attachments
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Support devices for higher production rate.
To reduce unit cost of production
d. Selection of Cutting tools and Inspection gauges
To reduced the production time
Separate tools for initial course machining and for fine finishing
Accurate inspection at a faster rate.
Find setup time and standard time for each operation
Preparation of Operation and Route sheets.
3A. 5 CHARACTERISTICS OF PRODUCTION PROCESS SYSTEMS
a) Job Production
In job production the whole product is looked as one job which is
to be completed before going on
to next. The most common examples are building a ship or a large
civil construction job. Job production is
hot confined to large projects, it could be the making of a
special piece of equipment or a tool.
b) Batch Production
If qualities of more than one are being made, it is sometimes
convenient to split the productions
into a series of manufacturing stages or operations. Each
operation is completed as one of the single items
being made, before the next operation is started. In this way a
group of identical products, or a batch are
made, which move through the production process together.
If more than one types of product is being made, then hatches of
different products may be
moving around the shop floor some times requiring operations from
the same machine. This leads to
problems of how long a machine should be processing a batch of one
tope of product before going on to
the next process, a different one, or which batch should be worked
on first. This type of problem tends to
make the planning and control of batch production a difficult
task.
c) Flow Production
When there is a continuous demand for a product, it is some time
worthwhile setting-up facilities
to make that product and no other product. In these circumstances
flow production may be the best way
of operating. Here the manufacturing is broken down into
operations, but each unit moves, or flows, from
one operation to the next individually, and not as one of a batch
example are motor manufacturing,
fertilizer, pharmaceutical and urea manufacturing. Since only one
product is being made there are no
problems about priorities, but it is necessary to balance the work
load at all stages of manufacture.
Examples are motor car manufacturing.
d) Intermitted production
The intermittent production system examples are machine hop
production, building contractor.
The continuous production examples are chemical plants automobile
industry etc. most of the companies
cannot be classified straight as intermittent or continent
production, rather in one department of the
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company continuous production is there while in other departments
intermittent production exists. The
time required for a continuous production system is always less
than the intermittent production systems.
The assembly line production of cars or scooters where the product
is coming off every few minutes is
considered as continuous production. On the other hand in
intermittent production systems the products
are in a state of partial completion for several weeks or days.
e) Continuous production
In continuous production system, the most common material handling
equipments are belt
conveyors, roller conveyors, chutes, rails etc. it is because in
continuous production systems one or a few
standard products are manufactured with pre-determined sequence of
operations with inflexible material
handling devices. In intermittent production system portable
material handling equipments are used and
various products are produced with greater flexibility in the
system.
Continuous production system require a larger investment than
intermittent production system
because of fixed path material handling equipments, costly control
mechanism and special purpose
machines for various operations. Even the marketing techniques
also differ for continuous production
system and intermittent production system.
Intermittent production system the marketing efforts are directed
towards meeting the individual
orders for various products while in continuous production the
marketing efforts are directed to wards
developing distribution channels for the large volume of out put.
The design of a production system starts
with the firm and re-occurs intermittently when redesign is
necessary. The major decision in the design of
production system is the location of plant. Once the location, has
been decided the next decision related
to layout of facilities. Another problem which concerns the
decision of production system is how products
are designed and manufactured.
3A . 6 RELATIONSHIP BETWEEN PROCESS PLANNING AND OTHER POM
ACTIVITIES
Process planning is the basis for the design of buildings, layout
of facilities and selection of
production equipment and machinery. Process planning also affects
quality control, human resource
requirements, job design and capacity of the plant. Process design
determines the details of how
products/service will be produced.
Process planning and process design describe the specific steps in
the production process and the
linkages among the steps that will enable the production system to
produce products /services of the
desired quality in the required quantity, at the tome customers
want them and at the budgeted cost.
Intense process planning may be required for new products /
services. Process re-planning may
also occur as capacity needs change, business or market conditions
change and technology improvements
take place in materials and machinery.
3A. 7 FACTOR AFFECTING PROCESS DESIGN
The basic factors that affect the design of manufacturing process
are:
Nature of product/service demand
Degree of automation
Degree of vertical integration
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Level of product/service quality
Product/service and volume flexibility
Degree of customer contact
The equipment that is available or that can be procured for the
manufactur of the product.
3A. 8 TYPE OF PROCESS DESIGNS
The basic type of production system and the finished goods
inventory policy to be used must be
decided at the earliest stages of process planning. The common
type of production system are:
(i) Product-focused production system
(ii) Process-focused production system
(iii) Group-technology/cellular manufacturing system
3A. 9 PROCESS FORM SELECTION WITH PLC PHASES
Because fixed and variable cost tend to differ from one form of
production process to another,
economic analysis is used for comparing alternative processing
plans for the production of products.When
deciding among the types of production processing organizations,
it is important to consider the cost of
each alternative. The cost function of processing alternatives,
the concept of operating leverage,
break-even-analysis and financial analysis are important aspects
of economic analysis.
The amount of capital required for each type of process design
tends to be different. Capital costs
are fixed charges that occur every month. The fixed costs are
greater when the initial cost of equipment,
buildings and other fixed assets are high. The variable costs –
the costs which vary with the volume of
products produced in each month are also different for different
forms of production processing systems.
Automated assembly line has the highest fixed cost as it consists
of expensive robotics, computer
controls and fixed-position material-handling equipments. On the
other hand, the variable costs, (labour,
material and variable overhead) for the automated assembly line is
the least.
The fixed costs and variable costs of cellular manufacturing are
intermediate and for the job shop,
the fixed costs are very low and the variable costs are very high.
The conclusion is – If capital availability is not a factor and
annual production costs (sum of fixed
costs and variable costs) are the predominant consideration, the
preferred process design depends on the
production volume of the product.
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3B. WORK STUDY
3B. 1 INTRODUCTION
Work study is mainly concerned with the examination of human work.
In fact planning cannot be
done unless one knows how long it will take to do a particular
job. It is important in modern time that our
lives take cognizance of time. Time is very important to the
manufacturer who must keep to promise, to
estimate quantities, and to other industrial and business
arrangements. The need for this managerial tool
arose in the middle of nineteenth century, when the greater use of
machinery and increasing size of
manufacturing units necessitated a more efficient means of control
ling production schedules. It was F.W.
Taylor who argued that greater, attention should be paid to be an
of timing tasks Taylor advocated the
breaking down of a task into what the termed – elements of work
and the timing of these elements
separately with the aid of a stop watch. He also emphasized the
use of a differential piece rate system. In
this system a strong incentive was offered to those who reached or
surpassed the standard established by
Taylor’s time study method.
A contemporary of F.W. Taylor was Gilbreth; he and his wife, Dr.
Lilian Gilbreth were sure that the
in which work was done was far more important than trying to
devise timing systems of how long it took
to do a set task. Gilbreth often found it necessary to take motion
pictures and examine them frame by
frame to examine the smallest elements of movements.
Improving the Productivity is an important tool to increase the
profitability and overall efficiency of
an organisatoin. Higher productivity means increase in output with
lesser expenditure. i.e. by increasing
Productivity, more quantity of goods are produced at cheaper cost.
To improve the productivity, various
working methods applied in the organisatoin have to be revamped.
Method Study is a technique used to
simplify the method of doing works. By method study, efficient and
economical methods are developed.
Improved methods will reduce tiredness of the workers, and hence
Productivity will certainly increase.
3B. 2 WORK STUDY
Work Study investigates the work done in an organization and it
aims at finding the best and most
efficient way of using available resources, i.e. men, material,
money and machinery. The main stress of
work study is to examine the human work in all its contexts and to
motivate the human efforts at all levels
to make the life productive.
DEFINITION
Russel M. Currie defines work study as follows:
“The systematic objectives and critical examination of all the
factors governing the operations
efficiency of any specified activity in order to effect
improvement.”
Another definition by Brig. K. Pannather says: “Work Study may be
defined as one of the
management techniques which can be applied to achieve the optimum
use of the resources available to an
establishment for the accomplishment of the work, it is engaged
in.”
Frederick W. Taylor, one of the pioneers in the field of Work
Study says that the greatest production
results when each worker is given a definite task to be performed
in a definite time in a definite manner.”
This is the foundation on which modern Work Study stands today.
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“Time Study” means the straight timing of work elements. Work
measurement – it is that human
effort is somehow measured and one of its objectives is the
installation of financial incentive systems of
payment. The object of motion study, method study, micro motion
study is to devise new and improved
working methods. Maynard suggested that to obtain the maximum
effectiveness from the study of work It
was necessary to use all the known techniques. He named his
systematic approach to the development of
improved methods “method engineering”.
Work study is term used to embrace techniques of Method Study and
work measurement which are
used to ensure the best possible use of human and material
resources in carrying out a specified activity.
3B. 3 IMPORTANCE AND SCOPE
Work study is not a theoretical concept but essentially a
practical one dealing with human beings
who have their own style and attitude. The success of work study
depends upon the existence of good
relations – between managements and workers. Work study involves
lot of changes of various kinds of
working methods. Since people in general do not like changes but
prefer to carry on as they are already
doing. There will always be a tendency to resist any new
methods-suggested by work study officers. But if
relations are good and the workers have confidence in the ability,
integrity and fair mindedness of work
study man, there is a good chance that sound proposals will be
accepted willingly by the workers.
3B. 4 VARIOUS MODELS
The layout diagram: It is a floor plant upon which the arrangement
of all equipment is marked to scale.
Such a diagram help an investigator record his findings in a form
which is simple to visualize.
FLOW DIAGRAM: This is a sketch or model to scale of the layout of
work places, machines, equipments,
floor areas and building particularly showing the location or all
activities in a flow process charts. This also
indicates the paths and movements followed by men, materials,
equipments in executing the activities.
STRING DIAGRAM: It is essentially the same scale plan of the
layout as used in the flow diagram with the
only difference that movements are shown by continuous threads.
This diagram will help us in finding out
the points of congestion band back tracking. Better routes could be
chosen by following different routing
of the thread and comparing it with the previous routing.
3B. 5 SIGNIFICANCE OF THE WORK STUDY
Work Study can be applied to any field of activity. Work Study
finds the defects in the organisation.
Work Study is always the first technique applied for increasing
production. Work Study techniques are
applied wherever human work if performed. The techniques of Work
Study are necessary in the following
circumstances
Where the Productions Processes is time consuming
When the rejection of finished goods is at a higher rate
Where the efficiency in production is low
If incentive wage plans linked with bonus is in practice in the
organisatoin.
PRODUCTION AND OPERATIONS MANAGEMENT
Work Study techniques are applied in Industries) Production
operations, research and development,
marketing, sales and distribution) offices, stores, and warehouses
material handling, design building and
other constructions, transport, hospital, army and agriculture.
3B. 6 WORK STUDY AS A SCIENCE
Work study have been criticized on the grounds that many of its
techniques depend upon human
judgment and therefore the result have only limited application.
Let us see how far this criticism hold true.
It is true that some of the techniques such as rating as used in
work measurement depend upon the
estimates of work study man. Thus properly trained and qualified
man with correct judgment should be
acceptable for all practical purposes. As we know that it any time
the predictions of weather forecasts are
wide of the truth but this by no means that we should ignore all
weather forecasts. In any area new
concepts and knowledge keep emerging similarly in work study new
and more accurate technique will
emerge.
3B. 6 WORK STUDY AND PRODUCTIVITY
Productivity increase is the key factor in raising the standard of
living Work Study indicates how
resources can be effectively utilized and study would help in
realizing this aim.
Selecting the Work to be Studied: We could select for study the
work that is likely to have the
longest production run, offers the greatest scope for improvement,
and which promises the greatest
financial saving for a given outlay.
Recording Facts: The techniques used in recording the, facts may
be divided into following three
categories:
(a) Process and time
(b) Charts
(c) Process Charts
It is useful diagrammatic means of presenting information on the
major activities associated with
particular investigation.
The advantages of process chart are:
(a) It is convenient means of presenting ‘information’
(b) It shows clearly the relationship between several sets of
data.
(c) It permits quick analysis of the problem
(d) It provides a record for future reference.
Charts are like machines, which require the fuels on which it
runs. Chart is a means to an end. It
cannot solve the problems by itself but it shows up inefficiencies
and the way to speedy solution.
3B. 7 OUTLINE PROCESS CHARTS
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It is graphic presentations of the points at which materials, are
introduced into the process, the
sequences of operations and inspections carried out. Chart
includes information as the time required the
grade of labour, type and location of machine employed. Outline
process chart records the following two
type of activities.
Flow process chart: It is a graphic representation of the sequence
of all operations. Transportation,
inspections, delays, storage etc. occurring during a process or
procedure. This will include in greater
details all relevant information for analysis such as time of each
activity distance moved frequency of
movement.
The Flow Process Chart will assist in drawing a complete sequence
of events occurring in process
and keeps us in finding the delays, improper handling frequency of
movement and keeps us in finding the
tracking etc.
It is a means of recording information and is an extension of
outline process chart. In addition to
two activities – operation and inspection of outline process
chart, it has three further activities:
(a) Transportations
(b) Delays
(c) Storages
Flow process charts can relate to material or individuals
MULTIPLE ACTIVITY CHART: These charts are the pictorial
representative of relationship between man-time
and machine time. These charts show the relation between two or
more separate but selected operation
cycles and may also be used to study the work of several operators
on a group of operations. Multiple
activity charts help us considerable to visualize the sequence and
relationship of event.
TRAVEL CHARTS: This is drawn in conjunction with a flow diagram.
In the case of multi-products
and non-standardized products this chart helps us to indicate flow
between processes, departments of
shop areas.
Work Study is a short term approach to the problems of
productivity. The advantages of Work Study
are as follows:
a) It helps uniform and improved production flow
b) It helps higher productive efficiency
c) Manufacturing costs are greatly reduced
d) It helps us to secure proper performance of the plant,
materials and methods through
standardization process.
e) It helps in the fixations of wages of different categories of
personnel
f) It helps to introduce the methods and standards as accepted
routine practice.
g) It helps better employer- employee relations. Also, it assures
better service to customers.
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h) Job security and job satisfaction to workers is also ensured by
work study
i) It helps ensure the best possible and most effective use of
existing and or potential resources
of the firm.
3B. 9 USES OF TIME STUDY
It is useful in determining the standard time for various
operators which help in fixing wage
rates and incentives
It is useful to estimate the cost of a product accurately
It helps in production control
It helps in predicting accurately as to when the work will be completed
and hence customers
can be promised to take delivery on a fixed date.
Using the time study techniques, it is easier to find out how many
machines an operator could
easily operate at a time and work can be allotted to him according
to his capability.
Now, let us see the various procedures for conducting Time Study.
3B. 10 TECHNIQUES OF WORK STUDY
Work Study consists of methods study (or motion study) and work
measurement (or Time Study)
Techniques of Work Study
Methods Study (Motion Study)
Time Study (Work Measurement)
USES
Following are the important uses of work study
(a) Direct means of raising productivity
(b) It is systematic; to factor is overlooked
(c) Most accurate method and yet provide production planning and
control and incentives.
(d) It is most important tool of analysis.
(e) Every one concerned with industry benefit from it such as
customer, worker and management.
3B. 11 DEFINITION METHODS STUDY
Method Study is a technique which analyses each operation of a
given piece of work very closely in
order to eliminate unnecessary operations and to approach the
quickest and easiest method of performing
each necessary operation; it includes the standardization of
equipment, method and working conditions;
and training of the operator to follow the standard method.
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Method Study may also be defined as the systematic investigation
of the existing method of doing
a job in order to develop and install an easy, rapid, efficient
and effective and less fatiguing procedure for
doing the same and at lower costs. this is generally achieved y
eliminating unnecessary motions involved
in a certain procedure or by charging the sequence of operations
or the process itself.
Frank Gilbreth defines method study as “the science of eliminating
wastefulness resulting from
ill-directed and inefficient motions”. The main purpose is to find
the scheme of least wastage of labour.
The modern concept of method study is a development of Gilbreth’s.
Technique of Motion Study.
3B. 12 OBJECTIVES OF METHOD STUDY
The following are the objectives of Method Study:
a) Improvement of manufacturing processes and methods. Better
product quality
b) Improvement of working conditions
c) Improvement to plant layout and work place layout
d) Reducing the human effort and factique
e) Reduced health hazards
f) Reducing material handling.
g) Improvement of plant and equipment design
h) Improvement in the utility of materials, machines and man power
and
i) Ensuring safety
In the following paragraphs, let us discuss in brief the various
procedures involved in Method Study.
3B. 13 METHOD STUDY PROCEDURE
a) Select the work worth studying and define the objectives to be
achieved. An objective may be to
reduce the manufacturing cost or to reduce bottleneck or to reduce
fatigue incurred by the
workers in order to increasing their efficiency.
b) Record all the relevant information pertaining to the existing
method in details and in the form
of a chart to obtain a more clear picture about the same.
Recording can be done with the help
of the following aids:
Process Charts
Diagrams
Motion and Film Analysis and
Models
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c) Examine the recorded events critically and in sequence. It
involves answer to a number of
questions. An activity can be eliminated, simplified or combined
with another. The likely
questions to be asked are:
Purpose - What is done?
Person - Who does it?
Place - Where it is done?
Means - How is it done?
Sequence - When is it done?
d) Develop the best method as resulted form critical examination
and record it. The developed
method should be practical, safe effective and economical.
e) Installation of the (best) developed method or the improved
method. It involves planning,
arranging and implementing. During planning and arranging, necessary
arrangements of
resources, equipments, tools and instruction to workers overtime
etc. are made. The actual
installation involves the introduction of developed method as
standard practice.
f) Maintain the new method
We should ensure the proper functioning of the installed method by
periodic checks and
verifications. If there are any deviations, the reasons for
deviation should be explored and
corrected. Views of the workers, supervisors and other person
related with the authorize method
can be of immense help in exploring further improvements.
The above mentioned are the procedures and steps in Method Study.
A chapter on method study will be incomplete without a mention
about the Therbligs’ motion study.
3B. 14 THERBLIGS
Frank Gilbreth developed a set of 17 elementary motions commonly
found in manual operations
and called them ‘Therbligs’ reversed spelling of his name. We know
that motion study is used for deciding
the best way of doing work for which preent and proposed methods
are observed by experts by recording
on charts. For the purpose of recording the motions, he split up
different motion of process into 17
fundamental elements made by various members of human body and
each event was allotted a symbol
and letter abbreviation. These symbols and abbreviations are used
for preparing Motion Study charts.
3B. 15 PROCESS CHART
A chart representing a process is called as a process chart. A
process chart records graphically or
diagrammatically, in sequence the movements connected with a
process. This chart portrays and process
with the help of a set of symbols and aids in better understanding
and examining the process with a
purpose to improve the same.
The process charts are of three types:
a) Outline Process Chart
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b) Flow Process Chart and
c) Two Handed Process Chart
a) OUTLINE PROCESS CHART
An outline process chart surveys and records an overall picture of
the process and sates only main
events sequence wise. It considers only main operations and
inspections.
b) Flow Process Chart
This is a graphic representation of operation, transportation,
inspection, delays and storage
occurring during production. This also gives the information
regarding distances moved and times
required for different items such as transportation and, delays
and inspection etc. It is usually prepared for
one component of an assembly at a time.
The first step in preparing this chart is filling out of the
headings. Each activity is listed in order as
the job is following thorough the plant and notations are made as
shown. The symbols in such charts are
short hand tools and serve as sign posts to make critical areas
for improvement. In this way by preparing
Flow Process Chart, a processor a job can be analyzed step by
step. Activities can be eliminated in some
cases, combined in others, rearranged for more effective
processing or simplified.
c) Tow Handled Process Chart
Two handed process chart records the activities of the left hand
and right hand of an operator as
related to each other.
3B. 16 FLOW DIAGRAM
A flow diagram is a drawing or a diagram, which is drawn to scale.
It shows the relative position of
production machinery, jigs, fixtures gangways etc. and marks the
paths followed by men and materials.
Process charts indicate the sequence of events, they do not
illustrate the movements of men,
materials etc. while the work is being accomplished. To know the
path of movement of men and materials
and to reduce unwanted movements these flow diagrams are
preferred.
3B. 17 STRING DIAGRAM
A string diagram is preferred over a flow diagram, if paths and
movements are congested and
repetitive. A string diagram is a layout drawing on which a length
of string is used to record the extent as
well as the pattern of movement of a worker or piece of equipment
working within a limited area during a
certain period of time. As explained earlier, it is used to study
where the journeys and irregular in distance
and the movements are repetitive and congested.
3B. 18 TIME STUDY
As discussed earlier, method study aims at reducing unwanted and
unnecessary motions while
performing a job. Once the method study has developed, an improved
procedure for doing a job, the work
measurement or time study will find the time allowed to complete
the job.
Timely study or work measurement is the art of observing and
recording the time required to do
each detailed element of an industrial operation. Industrial
operation means manual, mental and
PRODUCTION AND OPERATIONS MANAGEMENT
machining operations. Manual time is divided into three types of
operation i.e. handling of tools, handling
of machines and handling of materials. Mental time includes time
taken by the worker for thinking over
some operations. Machining time includes time taken by the
machines in doing its share of work.
So, time study standardizes the time taken by an average worker to
perform these operations. Time
study or work measurements is also defined as follows “it is the
application of techniques designed to
establish the time for a qualified worker to carryout a specified
job at a defined level of performance.
3B.19 OBJECTIVES OF TIME STUDY
Production cost of any commodity is made of three components
Raw Material Cost
Overheads
Labour Cost.
A production manager can easily predict the cost of raw material
and with some past experience
and judgment overheads can be estimated pretty accurately. To
estimate labour cost, we need to know the
labour time. The practical experience of production specialists
helps them exercise considerate judgment
in estimating direct labour time. However, costly errors can occur
if personal judgment is used exclusively.
Time studies are conducted to make precise evaluation of direct
labour time.
These time standards, in addition to establishing standard labor
costs, also establish capacity of
productive equipment. The standards are thus used for scheduling
production orders.
Another use of time study is that as a result of time study, a
time study engineer inevitably
discovers constructive refinements in operation methods tooling,
plant lay-out and materials handling.
Thus he is in a position to compare the various alternatives and
recommend the best possible method.
Also time standards are used for setting pay incentives. Any body
who can do better than
standards by his extra skill will earn more.
Work Measurement
a) Determines the time required to do a job. Also, it compares
various alternative methods and
established the fastest method.
b) Decided the manpower required for a lob and also determines the
equipment requirements.
c) Provides information for effective production planning and
maintenance procedures.
d) Aids in calculating exact delivery dates.
e) Decides realistic labour budgeting and provides a basis for
standard costing system
f) Provides for a sound incentive schemes and
g) Result in effective labour control.
3B. 21 PROCEDURE OF WORK MEASUREMENT
PRODUCTION AND OPERATIONS MANAGEMENT
The general procedure followed in Work Measurement is as follows:
(a) The job is broken down in its elements
(b) The observed time for each element is recorded
(c) Basic time is determined for those elements for which data is
not available.
(d) The values so determined for nay of the elements which could
conceivably secure in another job
are added to the records of basic times.
(e) Determine the frequency of occurrence of each element in the
job, multiply the work content of
each element with its frequency and add up the time to arrive at
the work content for the job.
(f) The proportion of rest required is assessed and added to the
basic time for doing the work at the
standard rate of working and for recovering from the effort i.e.
the work content.
(g) The addition of the relaxation allowance may be made element
by element
(h) If there are any contingent delays a blanket allowance (not
exceeding 5% ) may be added since they
are not economical to measure.
3B. 22 MICRO MOTION FILMS
In many cases the high speed movements made by the operators
cannot be seen by the eye or with
stop watch. The technique of micro motion is used to record rapid
movements. It consists essentially of a
cine camera which takes a film of the operator’s movements.
Micro-motion study besides giving a more
accurate recording of both movements, also provides a permanent
record which can be studied at a latter
date also. The equipment for micro motion study is a 16 mm cine
camera, a tripod and exposure meter
and a timing clock known as microchronometer.
Microchronometers is provided with a self-starting motor with
geared movement designed to read
1/2000th of a minute.
3B. 23 MEMOTION TECHNIQUE
It is technique name after its inventor Marvin E. Mundel who
developed this particular use of the
cine camera for recording industrial activities and subsequent
analysis of the film. It is mainly used to
sgudy the work of dentist, a pharmacist and a group of men in a
foundry. This technique is mainly used
for long and irregular activities and work of a group of people.
The equipment required for memotion is a
cine camera capable of carrying a film magazine or at least 30
meters. Memotion is a kin to activity
sampling activity.
It is the application of techniques designed to establish the time
for a qualified, worker to carry out
a specified job at a defined level of performance. Work
measurement or time study is the technique for
determining the standard time to perform a specific task. In other
words motion study and time study is
the systematic study of work system with the purpose of.
(i) Developing the desired system and method usually the one with
the lowest cost.
(j) Standardize the system and methods
PRODUCTION AND OPERATIONS MANAGEMENT
(k) Determining the time required by a qualified and properly
trained person working at a normal pace
to do a specific ‘operation.
Work measurement, as the name suggests, provides management, with
a means of measuring the
time taken in the performance of an application for series of
operation in such a way that ineffective time
is shown up and can be separated from effective time. In this way,
its existence, nature and extent become
known where previously they were concealed within the total. One
of the surprising thing about factories
where work measurement ahs never been employed is the amount of
ineffective time where very existence
is unsuspected or which is accepted as the “usual thing” and
something inevitable that no one can do
much about built into the process. Once the existence of
ineffective time has been revealed, and the
reasons for it was traced down, steps can usually be taken to
deduce it.
Here work measurement ahs another role to play. Not only ‘Can it
reveal the existence of
ineffective time; it can also be used to set standard time for
carrying the work, so that if an ineffective time
‘does creep in later on it will immediately be shown up as an
excess over the standard time and will thus
be brought to the attention of the management. Work measurement
may start a chain reaction throughout
the organisation.
3B. 24 USEFULENSS OF TIME MEASUREMENT
It is indeed useful to the management to know how long it should
take to carry out various kinds of
work in a plant. Let us discuss various uses:
(a) It reveals the capacity of each machine and enables the
planning department to apportion work
correctly
(b) It increases accuracy in forecasting delivery dates.
(c) It is useful in costing
(d) It enables reliable forecasts to be made of machine when a new
department or factory is planned
(e) It helps in choosing the bets method
(f) It helps to prevent misuse of manpower in each department
(g) It fosters the development of equitable incentive payments
system
It is the oldest work measurement technique. It is regarded as the
fundamental technique. A
systematic method study should be carried out before the time
study because it is not good carrying out a
time study on any work until the simplest way of carrying out that
work has been determined by a
systematic method study.
3B. 25 PROCEDURES
For conducting Time Study, average workers and average machines
are selected and the study is
conducted by the Time Study expert. He is normally expected to be
familiar with all the information related
to the job and should be thorough with all details or the job. To
conduct the Time Study, a suitable
location is found out in such a manner that the expert would be in
a position to watch the operations and
movements of the workers without disturbing them from suitable
distance.
PRODUCTION AND OPERATIONS MANAGEMENT
Analysis of work
Standardization of methods and
Making Time Study
We shall discus the above three stages in Time Study in detail.
1. Analysis of work
First, the complete job and its operations are split up into
various elements. These elements are
finalized after conducting Motion Study in the end, time required
for job preparation, cleaning of
machine and oiling etc. are also calculated. Thus, time study
includes all the tasks performed by
the worker and not only the effective work.
2. Standardization of Methods
Before conducting Time Study, all the constituents of the job such
as materials, equipments, tools,
working condition and methods are standardized.
3. Making Time Study
Time Study is done on a printed Time Study Record which is fixed
on a board, known as Time Study
Board. On one corner (generally right hand top corner) a
Stop-watch is placed. This Stop Watch
should have a decimal scale dial so that it can read up to 0.01
minute.
Different time reading of one element is recorded in the
corresponding columns of the Record
Sheet. Several sets of readings are taken to arrive at an accurate
result. After noting all these
readings average time is to calculated. This average time multiplied
by a leaveling factor also called
Rating Factor which is generally assumed as 110-120% to get the
time required by normal worker.
A brief explanation about Rating Factor is warranted here.
3B. 26 RATING FACTOR
The study engineer multiplies actual time with a factor known as
“Rating Factor” or leveling Factor
to get the average time, which a normal worker would take. This is
expressed as a percentage of the
efficiency of representative operator, which indicates how
efficient an operator in comparison to some of
his average fellow workers.
Performance Rating = (Observed Performance / Normal Performance )
x 100
3B. 27 NORMAL TIME AND STANDARD TIME
This multiple of average time with the rating factor is known is
“Normal Time.” Some allowance
personal (5%), fatigue allowance (20%) and preparation allowance
(5%) are added in the normal time to
obtain the standard time. Thus, standard time is the basis for the
calculation of wages and incentives. So,
Normal Time = (Average Time x Rating Factor)
Standard Time = (Normal Time) + Other Allowances
3B. 28 ALLOWANCES
PRODUCTION AND OPERATIONS MANAGEMENT
In this connection, it should be mentioned here that it is not
possible for a worker to do his job
continuously without any break. There are many interruptions (stoppage
of work) taking place. Extra time
is added to the basic time to compensate this interruption. This
extra time given is known as allowance.
Generally, interruptions occur due to the following:
1. Personal Factors: Going for drinking water, toilet etc.
2. Nature of Work: Taking rest after hard work
3. Other Factors: Tool breakage, listening to supervisor etc.
Various types of allowance are explained below:
Figure : 3.2 Standard Time
1. Rest and Personal allowance
This is the allowance given for the personal needs of the worker,
(viz.) going to toilet, drinking water,
taking rest etc. I’ersonal allowance given, depends upon the
working condition and the nature of work. For
example, heavy work at high temperature (working near furnace)
needs more allowance. Light work, like
radio assembly needs lesser allowance. This allowance is also
known as relaxation allowance.
2. Process Allowance:
This is also known as unavoidable delay. A worker working in an
incentive system may have to be ideal
due to unavoidable delays. This delay may be due to process,
machine operation, waiting for work, waiting
for material etc. to c this delay, process allowance is given
3. Contingency Allowance:
In a shop there may be small delays due to
Waiting for the inspector
Consulting the supervisor
Obtaining special tools etc.
These delay are of very short duration. The allowance given to
compensate these delays is called
contingency allowance. Generally 5% of basic time is given as
contingency allowance.
4. Special Allowance:
In a shop, some activities take place occasionally. These
activities will not be part of he production cycle.
But, these are necessary for production work. Examples of these
activities are:
Tool resting
Cleaning
Tool maintenance
PRODUCTION AND OPERATIONS MANAGEMENT
Shut down
For these activities and allowance known as special allowance is
given
5. Policy Allowance
This is an allowance given according to the policy of the
management. It is not includes for calculating the
standard time. This is an extra benefit given by the management to
the workers. This allowance is given to
increase the worker’s earnings.
As explained earlier, while time study is made under the stop
watch method, due consideration is given for
the above allowances.
3B. 29 JOB DESIGN
There are strategic decisions – involving the design of products
and / or services and the location of the
system – which are an integral part of the overall productive
system design. The core of that productive
system, however, is located in the complex of technology and
people where the productive process is
centered – in factories, hospitals, banks, offices etc. We already
noted that the entire design process
contains interdependent components, and that the products,
services, and locations are partially
influenced by the core productive process, and vice versa. Since
these productive systems involve the
about blending of technology and people to form a core productive
system, they often are called
socio-technical system.
The goal of the entire design process is to develop a rationale
for the organization of the work to be done,
and to relate this rationale to machines and technology in tems of
work sharing between worker and
machines, work flow, and physical facilities. The layout, which on
the surface shows the spatial
relationships, illustrates the physical integration of these
factors. Whether or not the layout permits an
effective design from points of view other than work flow and
physical efficiency depends on the
effectiveness of process planning and job design, and how
technology and people are molded into a
system.
Now we can consider the really fundamental alternative of division
of labor versus broad spectrum jobs –
grouping tasks into jobs at fairly homogenous skill levels versus
vertically integrating tasks into jobs. It is
at these points that jobs can be created that either satisfies and
fulfill workers or dehumanize them.
We shall consider process planning, job design and layout as an
integral whole in the attempt to avoid the
known effects that result when these elements are dealt with as
separate independent concepts. The
known effects are that process planning (that is technology and
layout) has been thought of as the
independent variable and that people and job designs have been
thought of as the dependent variables. In
that kind of framework, job designs were viewed as the results of
process or technology planning.
Currently developing concepts and practices consider the two
components jointly to produce designs that
satisfy the needs of both kinds of variables.
3B. 30 TECHNOLOGICAL VIEW OF PROCESS PLANNING AND JOB DESIGN
While the general methods we shall describe were developed in
manufacturing systems, they have been
adapted and widely used in many other situations (e.g. offices,
banks, hospitals etc. ) Thus, although we
will take our examples from manufacturing settings, the methods
are not restricted to only such settings.
PRODUCTION AND OPERATIONS MANAGEMENT
Process planning takes as its input the drawings or other
specifications that might indicate what is
to be made, and also the forecasts, orders, or contracts that
indicate how many are to be made. The
drawings then are analyzed to determine the overall scope of the
project. If it is a complex assembled
product, considerable effort may go into “exploding” the product
into its components of parts and
subassemblies.
Then, for each part, a detailed routing through the system is
developed. Technical knowledge of
processes, machines, and their capabilities is required, as well
as a knowledge of costs and production
economics. Ordinarily, a range of processing alternatives is
available. The selection may be influenced
strongly by the overall volume and projected stability of product
design.
3B. 31 PRODUCT ANALYSES
The product that is to be manufactured is analyzed from a
technological point of views to
determine what processes are required.
Assembly or “Gozinto” Charts: Schematic and graphic model-commonly
are developed to help visualize
the flow of material and the relationship of parts (e.g. where
they flow into the assembly process, which
parts make up subassemblies, and where the purchased parts are
used in the assembly sequence). Thus,
for the capacitor, a first step might be the preparation of an
“assembly chart” or, as it is often called, a
“Gozinto” (goes into) chart.
OPERATION PROCESS CHARTS:
Event Symbol Description
Operation It represents an action
Storage It represents a stage when
material (raw or finished)
awaits an action
Delay It represents a temporary of
an item
Transport It represents movement of an
item
Inspection It represents an act of
checking
Combined Activities
Operation cum
Transportation
First activity represents outer
part and second security the
inner part
PRODUCTION AND OPERATIONS MANAGEMENT
Inspection cum Operation
FIGURE : 3.3 ‘PROCESS CHART” SYMBOLS
If the product already is engineered, we have complete drawings
and specifications of the parts and their
dimensions, tolerances, and materials to be used. From the
specifications and the forecast, we can plan of
“how to manufacture”. Decision must be made concerning which parts
to purchase and which to
manufacture in-house. The engineering drawings specify the
locations, sizes, and tolerances for holes to
be drilled, surfaces to be finished, etc. for each part. With this
information, together with estimates of
quantities to be produced and of manufacturing processes, we can
specify the most economical equipment,
processes, and sequences of processes.
3B 32 CRITERIA AND VALUES
From the time of the Industrial Revolution to the present, the
main pressures that have influenced
the design of processes and jobs are productivity improvement and
economic optimization. These
pressures have been associated with specialization. Adam Smith
stated the advantages of division of labor
as the guiding principle, and managers have applied this principle
progressively over time. The
automotive-type assembly lines epitomize the result, although the
general division of labour principle has
been applied throughout history and currently is being applied in office
work as well as in other productive
systems.
In 1776, Adam Smith enumerated the three important advantages of
division of labor.
(1) The development of a skill or a dexterity when a single task
was performed repetitively.
(2) A saving of the time normally lost in changing from one
activity to the next.
(3) The invention of machines or tools that normally seemed to
follow when workers specialized their
efforts on tasks or restricted scope.
To these three advantages, Charles Babbage added a fourth, the
principles of limiting skills as a basis for
wage payment. Babbage noted that (a) wages paid were directed by
the most difficult or rarest skill
required by the jobs, (b) divisions of labour enabled skills to be
made homogenous within jobs more easily
and (c) for each job, one could purchase exactly the amount of
skill needed. The result would be a lower
total labor cost.
Beginning in the early 1930s, however, another criterion was
proposed as a counterbalance – job
satisfaction. Results of the famous Hawthorne experiments
indicated that workers responded to other
factors in the work situation. In the late 1940s, the value of the
job satisfaction criterion development from
a morale building program at IBM [1950]. The term job enlargement
was coined to describe the process of
reversing he continuing trend toward specialization. Practical
applications of job enlargement were written
up in the literature. These applications described improvements in
productivity and quality levels that
resulted, from combining operations to create jobs of broader
scope. While job enlargement concepts did
not specify any stopping rule either, they did provide a
counterbalancing criterion.
In commenting on job satisfaction research, Davis points to
several values held by the
organizations that applied the division of labor criterion,
throughout the industrial era. He points out these
widely held beliefs: that the worker could be viewed as an
operating unit, and as such, could be adjusted
PRODUCTION AND OPERATIONS MANAGEMENT
and changed by training and incentives to suit the needs of the
organization, that workers were viewed as
square parts and therefore were interchangeable in work
assignments, that labor was thought of as a
commodity to be bought and sold, that materialism, in its narrow
sense of achieving material comfort,
justified the means required to achieve it, and that many managers
regarded jobs as isolated events in the
lives of individuals – a non career.
Davis, however, is also critical of most job enlargement and job satisfaction
studies because they
almost invariably accept the technology as given and merely
attempt to maximize satisfaction within
technological constraints. He concludes that, throughout the
industrial era, as a basis for process planning
and job design, technology predominately has determined job
content. This even holds true for most of he
applications that consider job satisfactions as a criterion.
Other inputs:
Skill
Effort
Conditions
Consistency
b.) Synthetic Rating: It is the method of evaluating an operator’s
speed form predetermined motion time
values. The ratio between the predetermined motion time standard
for the element and the average actual
time volume in minutes for the same element is called performance
rating factor.
3B. 37 STANDARD PERFORMANCE
Standard Performance is the rate of output which a qualified
worker will naturally achieve without
over-exertion as an average – over the working day or shift
provided they know and adhere to the
specified method and provided they are motivated to apply
themselves to their work.
This performance is denoted as the one on the standard rating and
performance scales.
3B. 38 SCALES OF RATING
In order that a comparison between the observed rate of working
and the standard rate may be
made effectively, it is necessary to have numerical of scale
against which we make the assessment.
The rating can then be used as a factor by which the observed time
can be multiplied to give the
basic time which is the time, it would make the qualified worker,
motivated to apply himself & carryout the
element at standard rating.
There are several scales of rating where’ the most common of which
are those designated the
100-133 scale, the 60-80 the 75-100 and the British Standard Scale
which is 0-100.
*******
PRODUCTION AND OPERATIONS MANAGEMENT
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