Operation Management_dec 4-5- Work Study

8/8/2019 Operation Management_dec 4-5- Work Study

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OPERATIONS MANAGEMENT


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OPERATION MANAGEMENT

HR

PRODUCT

MATERIALS

SCHEDULING

FACILITIES

PLANNING

PROCESSES

LAYOUT


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Work Study

Managing Efficiency,Processes and Productivity:

- Time Study

- Method Study- Process Improvements

- Productivity Improvements

- Value Engineering /Cost Reduction


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Work Study

Method Study

- Methods of performing workand improve efficiency and economy

Work Measurement

- Time taken to do it,

with a view to rationalization, routinisation,utilisation , cost

and incentive improvement


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Work Study

Productivity:- A measure of performance

- Broadly a ratio of output to input

To evaluate productivity levels and identify areas of

improvement.


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Work Study

Methods, times and systems of performanceImprove methods get it right

- Method study

- O&M Ergonomics- Industrial & Systems Engineering

WORK STUDY

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Method Study Time Study

Examining a job and finding Determine the time necessary to perform

More efficient methods to a job and its elements

Perform


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Work Study

Method study StepsSelect


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Work Study

Time study:

- Select job & identify the work tasks

- Check the method- efficient/agreed?

- start a Time Study sheet & break work task into units

- several times with a stop watch & for a sample of workers, time measure

> Completion time for each unit of work in the job sequence

> Average for each worker

> Determine and apply worker effort rating for each worker

> Apply fatigue, personal & other allowances

From the observation data (worker average times) calculate standard time for the task

Fix standard time and enter into measured work manual/database.


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Time Study: Rating


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Assessing the effective speed of working of the operatorrelative to the observers concept of the rate corresponding tostandard rating.

Most time studies in industry are used to determine standard

times for setting workloads and also as a basis for incentiveplans.

Rating (the assessment of a workers rate of working) and theallowances to be given for recovery from fatigue.


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The qualified worker

Time studies should be made on a number of qualifiedworkers; and very fast or very slow workers should beavoided.

Different jobs require different human abilities. For example,some demand mental awareness, concentration, visualperception; others, physical strength; some acquired skill orspecial knowledge.

A qualified worker is one who has acquired the skill, knowledge

and other attributes to carry out the work in hand tosatisfactory standards of quantity, quality and safety

A representative worker is defined as one whose skill andperformance is the average of a group under consideration

and who is not necessarily a qualified worker.


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Standard rating and standard performance

The principal use of work measurement is to set time standardswhich can be used for a number of different purposes (includingprogram planning, estimating and as a basis for incentives) for

the various jobs.

It would be no use setting standards so high that only the bestones could attain them, since programs or estimates based onthem that would never be fulfilled.

to set standards well within the achievement of the slowestworkers would not be contributing to efficiency.


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Rating is the assessment of the workers rate of working relativeto the observers concept of the rate corresponding to standardpace.

By definition, rating is a comparison of the rate of workingobserved by the work study person with a picture of somestandard level in mind.

This standard level is the average rate at which qualifiedworkers will naturally work at a job, when using the correctmethod and apply it to their work.

This rate of working corresponds to the standard rating, and is

denoted by 100 on the recommended rating scale.


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Rating is the assessment of the workers rate of working relativeto the observers concept of the rate corresponding to standardpace.

Standard performance is the rate of output which qualifiedworkers will naturally achieve without over-exertion as anaverage over the working day or shift. This performance isdenoted as 100 on the standard rating and performance scales.

The rate of working most generally accepted in the UnitedKingdom and the United States, corresponding to the standardrating is equivalent to the speed of motion of the limbs of aman of average figure walking without a load in a straight line

on level ground at a speed of 4 miles an hour (6.4 kilometersper hour).


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What is rated?

The purpose of rating is to determine the standard time which can be maintained bythe average qualified worker and which can be used as a realistic basis for planning,

control and incentive schemes.

What the study person is concerned with is therefore the speed with which theoperator carries out the work, in relation to the study persons concept of a normalspeed. Speed of what?

Certainly not just speed of movement, because an unskilled operator may move

extremely fast and yet take longer to perform an operation than a skilled operativewho appears to be working quite slowly.


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What is rated?

The only thing that counts is the effective speed of the operation. Judgment of effectivespeed can only be acquired through experience and knowledge of the operations beingobserved. Should effort be rated, and if so, how?

The problem arises as soon as it becomes necessary to study jobs other than very lightwork where little muscular effort is required. Effort is very difficult to rate.

Operations involving mental activities (for example, judgment of finish in inspection of

work) are most difficult to assess.


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Factors affecting the rate of working

Differences in actual times for a particular element may be due to factorsoutside or within the control of the worker.

Factors outside of the operators control may be:

differences in the quality or other characteristics of the material used,although they may be within the prescribed tolerance limits;

changes in the operating efficiency of tools or equipment within their usefullife;

minor and unavoidable changes in methods or conditions of operation;

differences in the mental attention necessary for the performance of certainelements;

changes in climatic and other surrounding conditions such as light,temperature, etc.


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Factors affecting the rate of working

Factors within the operators control may be:

acceptable differences in the quality of the product; differences due to the individuals ability;

differences due to the attitude of mind, especially the attitudeto the organization for which he works.


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Scales of rating

The 0 -100 scales has, however, certain important advantages which have ledto its adoption as the British Standard.

How the rating factor is used

It is usual practice to round off ratings to the nearest multiple offive on the scale; that is to say, if the rate is judged to be 13 percent above standard, it would be put down at 115.

If the study persons ratings were always perfect, however manytimes an element were rated and timed, the results should bethat:

Observed time x rating = a constant

Rating


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Scales of rating

Provided that the element is of the type described as a constantelement and that it is always performed in the same way.

An example, expressed numerically, might read as follows:


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.

This basic time (0.20 minutes in the example) represents the time the

elements would take to perform (in the judgment of the observer) if the

operator were working at the standard rate, instead of the faster one actually

observed.


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Time study: From study to standard time

Basic time is the time for carrying out an element of work at standard rating,i. e.

Observed time x observed rating

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Standard rating


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Work content

The work content of a job or operation is defined as:

Basic time + relaxation allowance + any allowance for additional work,

i.e., that part of contingency allowance which represents work.


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Allowances

Many jobs require human effort, and some allowance must bemade for recovery from fatigue for relaxation. Allowance must

also be made to allow a worker to attend to personal needs; andother allowances (e.g. contingency allowances) may also have tobe added to the basic time in order to give the work content.

The difficulty experienced in preparing a universally accepted set

of exact allowances that can be applied to every workingsituation anywhere in the world is due to various reasons. Themost important among them are:

Factors related to the individual. If every worker in a particularworking area were to be considered individually, it might wellbe found that a thin, active, alert worker at the peak (top) ofphysical condition required a smaller allowance to recoverfrom fatigue than a fat, incompetent (unskilled) worker.


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Allowances

Factors related to the nature of the work itself. Many of the

tables developed for the calculation of allowances give figureswhich may be acceptable for light and medium work inindustry but which are inadequate when applied to operationsinvolving very heavy and exhausting work. (i.e., furnaces insteel mills).

Examples of these factors are: whether a worker has toperform the work standing up or sitting down, and positionduring work; whether force has to be used to move or carry loadsfrom one place to another; whether the work itself results inexcessive eye or mental strain, and so on.


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Allowances

Each of these will affect the amount of relaxation allowancesneeded.

Factors related to the environment. Particular relaxationallowances, have to be determined with due regard to variousenvironmental factors such as heat, humidity, noise, dirt,vibration, lighting intensity, dust, wet conditions, etc.


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Calculation of allowances

It will be seen from this model that relaxation allowances (which areintended to assist recovery from fatigue) are the only essential part of

the time added to the basic time.

Other allowances, such as contingency, policy and special allowances

are applied under certain conditions only.

Relaxation allowance is an addition to the basic time intended to

provide the worker with the opportunity to recover from the

physiological and psychological effects of carrying out specified work

under specified conditions and to allow attention to personal needs.

The amount of allowance will depend on the nature of the job.


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Relaxation allowances are calculated so as to allow the worker to recover fromfatigue.

Fatigue may be defined as a physical and/or mental weariness, real or imagined,existing in a person and harmfully affecting the ability to perform work. Theeffects of fatigue can be lessened by rest pauses, during which the bodyrecovers from its effort.

Allowances for fatigue are normally added element by element to the basictimes, so that a work value for each element is built up separately, the

element standard times being combined to give way the standard time for thewhole job or operation.

In this way it is possible to deal with any extra allowance which may berequired to compensate for severe climatic conditions, since the element maysometimes be performed in cool weather and sometimes when it is very hot.

Relaxation allowances have two major components:

fixed allowances and variable allowances.


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Relaxation allowances

Fixed allowances are composed of:

Allowances for personal needs. This allowance provides for thenecessity to leave the workplace to attend to personal needssuch as washing, going to the bathroom or getting a drink.

Common figures applied by many enterprises range from 5 to 7

per cent.

Allowances for basic fatigue. This allowance, always a constant,is given to take account of the energy expended while carryingout work and to lessen monotony.

A common figure is 4 per cent of basic time. This is considered tobe sufficient for a worker who carries out the job while seated,who is engaged on light work in good working conditions.


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Variable allowances are added to fixed allowances when workingconditions differ noticeably from those stated above, for instancebecause of poor environmental conditions that cannot be

improved, added stress and strain in performing the job inquestion, and so on.

Relaxation allowances are given as percentages of the basic time.They are normally calculated on an element-by-element basis.

Rest pauses

Relaxation allowances can be taken in the form of rest pauses.While there is no hard and fast rule governing rest pauses, a

common practice is to allow a 10 to 15 minute break at mid-morning and mid-afternoon, often joined with facilities for tea,coffee or cold drinks and snacks, and to permit the rest of therelaxation allowance to be taken at the good judgment of theworker.


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Variable allowances

Rest pauses are important for the following reasons:

They break up the monotony of the day.

They give workers the chance to recover from fatigue and toattend to personal needs.

They reduce the amount of time off taken by workers duringworking hours.

Where workers are working in conditions of heat, cold, noise orvibration it may be necessary to introduce mandatory rest pausesas part of a work-rest routine to ensure the health and safety ofthe workers.


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Other allowances

It is sometimes necessary to include allowances other than relaxation allowances in thecompilation of standard time.

Contingency allowances

A contingency allowance is a small allowance of time which may be included in astandard time to meet reasonable and expected items of work or delays.

The exact measurement of which is uneconomical because of their rare or irregular

occurrence

Contingency allowances should not be greater than 5 per cent, and should only begiven in cases where the study person is absolutely satisfied that the contingenciescannot be eliminated and that they are justified.

Special allowances

Special allowances may be given for any activities which are not normally part of theoperation cycle but which are essential to the satisfactory performance of the work.

Such allowances may be permanent or temporary; wherever possible, these allowancesshould be determined by time study.


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Start-up allowance to compensate for time taken by any work and

any enforced waiting time which necessarily occurs at the start ofa shift or work period before production can begin.

A shut-down allowance may be given for work or waiting timeoccurring at the end of the day.

A cleaning allowance is given when the worker has to give attentionfrom time to time to cleaning his machine or workplace.

Tool allowance is an allowance of time to cover the adjustment and

maintenance of tools.


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Some allowances are normally given per occasion or per batch. Such

allowances are;Set-up allowance, given to cover the time required for preparing a

machine or process for production, an operation which isnecessary at the start of production on a batch of fresh productsor components.

Dismantling allowance may be given, to cover the time needed formaking alterations to machine or process settings aftercompleting a run of production.

Reject allowance may be included in a standard time when theproduction of a proportion of defective products is inherent inthe process, but is perhaps more usually given as a temporary

addition to standard times, per job or per batch, if an occasionalbad group of material has to be worked.


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Learning allowances may be given to trainee operators engaged on

work for which standard times have been issued, as a temporarybenefit while they develop their ability.

Training allowance is a similar allowance given to an experiencedworker to compensate for the time he is required to spendinstructing a trainee, while both are working on jobs for whichstandard times have been set.

Implementation allowance, given to workers asked to adopt a newmethod or process to encourage them to attempt an enthusiasticimplementation of the new ways.

Small batch allowance is required to allow a worker working onsmall batches to decide what to do and how to go about it and

then to work up to a standard performance by practice andrepetition.


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Work Study

Example standard time calculation:Element Basic Time Relaxation% Effort% Standard time

1 2.50 10 110 3.03

2 4.80 10 110 5.81

3. 3.60 15 110 4.55

Standard time Total..13.39 minutes


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Work Study

Method Analysis Development of methods is a cooperative effort of

the design, process and methods analyst.

This is done both for jobs being done for the first

time and also as continuous improvement

The methods are evaluated and optimised on a

continuous basis.

Change in design, facilities and other variables leadto change in methods and hence need analysis.


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Work Study

Method analysis

Approach:

- The Process Chart approach

> Describe an existing method

> Analysts get idea with the clear description of the process

> This helps in understanding and improving the process

Some of the flow charts commonly used are:

- The Material Flow Chart

A graphic representation of the sequence of operations,transportations, Inspections, delays and storage occurring during the

process


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Work Study

Method analysis Operation occurs when object is intentionally changed in any of the

physical or chemical characteristics, assembled, disassembled from

another object or is prepared for another operation

Transportations occurs when an object is moved from one to another

place, except when such movement is a part of the operation Inspections occur when an object is examined for identification or is

verified for quality or quantity in any of its characteristics

Storages occur when an object is kept and protected against unauthorised

removal

Delays occur to an object when conditions, except those whichintentionally change the physical or chemical characteristics of the object

do not permit or require immediate performance for the next planned

step.


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Work Study

Method analysis

Process Chart characteristics:

Activity Symbol

Operation O

Transportation

Inspection

Storage

Delay

Wo

rk

Study

Method

ana

Work

StudyMethod

analysis


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Work Study

Method analysis

Work Station flow process chartIn the course of analysing, if analyst observes materials or men

movement, analyst will examine the methods being employed in various

work stations.

Workstation is defined as the area occupied by the operator and the

equipment with which he works.

Picks up box of flat plates

Carries box to inspection bench

Places box on the bench

Inspects flat plates

Places good plates in container

Carries container of good plates to skid and so on


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Work Study

Method analysis

Man and Machine Charts

A graphic representation of the coordinated activities of a man and a

machine described in terms of independent work, combined work andwaiting. The duration of various activities is represented by bars which

are drawn to length against time scale.


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Work Study

Motion Study

To study and improve the motion of an

operator for performing task.Operator Process chart:

A graphical presentation of coordinated activities of an operatorss right and left hands. These activities are described in terms of operations,

transportations, holds and delays.

An operation occurs whenever the hand picks up, drops, lays down, positions,uses

or assembles something.

Transportation occurs whenever the hand moves from one position to another at the

work place.

Hold occurs whenever the hand holds an object so that the other hand may do

something on the object

Delay occurs when the hand is idle, in the sense that it is not performing an operation,

a transportation or hold.


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Work Study

Motion Study The simultaneous motion cycle chart:

An improved Operator Process chart, where it yields a more

detailed description of the observed motion pattern and

hence is often more capable of revealing deficiencies and

hence more scope of improvements.

It observes and records actions like

Search,select,grasp,transport empty,transport

loaded,hold,release load,position,pre-

position,inspect,assemble,disassemble,use, unavoidabledelay, avoidable delay, plan, rest for overcoming fatigue

Operation Management_dec 4-5- Work Study

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Transcript of Operation Management_dec 4-5- Work Study