Chapter-8 Work Study and Setting Time Standards for Machines

8/13/2019 Chapter-8 Work Study and Setting Time Standards for Machines

http://slidepdf.com/reader/full/chapter-8-work-study-and-setting-time-standards-for-machines 1/29

WORK STUDY SOME DEFINITIONS

Work Study is the systematic examination of the methods of carryingon activities so as to improve the effective use of resources and to setup standards of performance for the activities being carried out.

Work Study succeeds because it is systematic both in the investigation

of the problem being considered and in the development of itssolution.

Techniques of work study are method study and work measurement.

Method study is the systematic recording and critical examination of ways of doing things in order to make improvements.

Work measurement is the application of techniques designed toestablish the time for a qualified worker to carry out a task at adefined rate of working.



Method study is the systematic recording and critical examination of ways of

doing things in order to make improvements.

The basic approach to method study consists of the following eight steps:

1. SELECT the work to be studied and define its boundaries.2. RECORD the relevant facts about the job by direct observation and

collect such additional data as may be needed from appropriate sources.

3. EXAMINE the way the job is being performed and challenge its purpose,place, sequence and method of performance.4. DEVELOP the most practical, economic and effective method.5. EVALUATE different alternatives to developing a new improved method,

and compare the cost-effectiveness of the selected new method with thecurrent method of performance.

6. DEFINE the new method in a clear manner and present it to thoseconcerned, management, supervisors and workers.

7. INSTALL the new method as standard practice and train the personsinvolved in applying it.

8. MAINTAIN the new method & introduce control procedures to prevent adrawback to the previous method of work.



Basic procedure of Work Study1. SELECT the job or process to be studied (M.S. & W.M.)

2. RECORD from direct observation everything that happens, using the most suitableof the recording techniques, so that the data will be in the most convenient form tobe analyzed (M.S. & W.M.)

3. EXAMINE the recorded facts critically and challenge everything that is done,considering in turn: the purpose of the activity; the place where it is performed; thesequence in which it is done; the person who is doing it; the means by which it isdone (M.S. & W.M.)

4. DEVELOP the most economic method of taking into account all the circumstances(M.S.)

5. MEASURE the quantity of work involved in the method selected and calculate astandard for its performance (W.M.)

6. DEFINE the new method and the related time so that it can always be identified(W.M.)

7. INSTALL the new method as agreed standard practice with the time allowed (M.S.)

8. MAINTAIN the new standard by proper control procedure (M.S.)



Selecting the job or work to be studied

There are three factors that should be kept in mind when

selecting a job.1. Economic or cost-effective considerations.

2. Technical considerations.

3. Human considerations.

1 . Economic considerations

It is obviously a waste of time to start or continue a long

investigation if the economic importance of a job issmall. Questions that should always be asked

Will it pay to begin a method study of this job? Or

Will it pay to continue this study?



Obvious choices for study are:

A. Key profit-generating or costly operations or ones with the largestScrap / waste rates.

B. Bottlenecks which are holding up other production operations, orlengthy operations that consume a great deal of time.

C. Operations involving repetitive work using a great deal of laborand ones that are likely to run for a long time.

D. Movements of material over long distances between workstations,those involving the use of a relatively large proportion of labor or

which require repeated handling of material.

One of the easiest techniques that can be used to identify key

operations as listed in part ( A ) is the Pareto analysis (sometimesalso referred to as “the ABC analysis of value analysis”).

The same observation can be extended by saying that among all theoperations in a given plant a small number account for the largest

share of cost or of profit, or the largest percentage of waste.



To illustrate the point we will consider the following example.

Let us assume that a certain enterprise produces 20 different products.Each of these products generates a certain profit. By listing the annual production and profit contribution one obtains the

results shown in table 6. The next step consists of rearranging these items in descending order of

importance according to profit. The result would then appear like the oneshown in table 7.

From table 7 it can be seen that three products only, listed as “ A items”, account for 60 per cent of the profit. These are the most profitable and any improvement in methods of

producing these particular products would reflect highly on profits. They would be a priority for study.

Products listed under “B”, which are seven in number, contribute 25 percent of the profit. They could then assume a second importance, whileproducts “C” would command the last priority since their contribution toprofit is minimal.

The same type of analysis can be conducted to determine “the most costlyproducts or processes” or “the products or processes that yield the highest waste”.

Those would then become a priority for study by the work study specialist.



2. Technical or technological considerations:

One of the important considerations is the desire by management to

acquire more advanced technology, i.e. in equipment or in processes.

Therefore, management may want to computerize its office paperwork orits inventory system, or to introduce automation in the productionoperations.

Before such steps are taken, a method study can point out the most

important needs of the enterprise in this respect. The introduction of new technology should therefore constitute an

important factor in the choice of methods of work to be investigated.

3. Human considerations:

Certain operations are often a cause of dissatisfaction by workers. They may bring on fatigue or monotony or may be unsafe to operate. The level of satisfaction should point to a need for method study. In a

similar fashion, a choice of a particular job for study may lead to anxiety orill feeling. The suggestion given here is to leave it alone.



Examine critically: by using the questioning technique.

The questioning technique is the means by which the critical examination

is conducted, each activity being subjected in turn to a systematic andprogressive series of questions.

The primary questions The questioning sequence used follows a well-established pattern which

examines:



In the first stage of the questioning technique, the purpose,place, sequence, person and means of every activity recorded are

systematically questioned, and a reason for each reply isrequired.



The secondary questions

The secondary questions cover the second stage of thequestioning technique, during which the answers to theprimary questions are subjected to further question todetermine whether possible alternatives of place, sequence,persons or means are feasible and preferable as a means ofimprovement upon the existing method

Therefore, during this second stage of questioning (havingasked already, about every activity recorded, what is doneand why is it done), the method study person goes on toinquire:

What else might be done? And, hence: What should bedone? In the same way, the answers already obtained onplace, sequence, person and means are subjected to furtherinquiry.



Combining the two primary questions with the two secondary questionsunder each of the headings “purpose, place”, etc., yields the followinglist, which sets out the questioning technique in full:

PURPOSE: What is done? Why is it done? What else might be done? What should be done?

PLACE: Where is it done? Why is it done there? Where else might it be done? Where should it be done?

SEQUENCE: When is it done? Why is it done then? When might it be done? When should it be done?

PERSON: Who does it? Why does that person do it? Who else might do it? Who should do it?

MEANS: How is it done? Why is it done that way? How else might it be done?How should it be done?

These questions, in the above sequence, must be askedsystematically every time a method study is undertaken.

They are the basis of successful method study.



Setting Time Standards for work

with machines

Plant and machine control

Plant and machine control is the name given to the procedures andmeans by which efficiency and utilization of units of plant andmachinery are planned and checked.

Before focusing on individual jobs, the analyst will examine first theoverall utilization of the machinery in Business; differentdepartments; and machine by machine in the case of particularlyexpensive items.

Then, decide the proper objectives for the application of work studyin the plant, and it will be clear whether labor productivity ormachine utilization is of primary importance.

The terms and concepts used in the study of machine utilization (orplant or process utilization) are described below. The relationshipbetween them is shown graphically in figure 115.



Machine maximum time is the maximum possible time during which a machine or group of machines could work within a givenperiod, e.g. 168 hours in one week or 24 hours in one day .

Machine available time is the time during which a machine could

work based on attendance time, i.e. working day or week plusovertime .

Machine idle time is the time during which a machine is availablefor production or ancillary work.

Machine ancillary time is the time when a machine is temporarilyout of productive using due to change-over, setting, cleaning, etc.



Machine down time is the time during which a machine cannot be

operated on production work due to breakdown, maintenancerequirements, or for other similar reasons.

Machine running time is the time during which a machine isactually operating, (i.e. the machine available time less any

machine down time, machine idle time, or machine ancillary time).

Machine running time at standard is the running time that

should be incurred (acquired) in producing the output if themachine is working under optimum conditions.

The most useful work measurement method for studying machineutilization is work sampling. It is convenient to express the resultsobtained from studies on machine utilization in the form of ratiosor indices.



For this purpose three indices are commonly used:

Machine utilization index, is the ratio of

Machine running time to machine available time.

Machine efficiency index, is the ratio of

Machine running time at standard to machine running time.

Machine effective utilization index, the ratio of Machine running time at standard to machine available time.

Machine effective utilization index ratio can be used to provide anindication of the scope for cost reduction that would be available ifthe machine were operated at full efficiency for the whole of the

working time.



The overall cycle time is the total time in which the job should be completed atstandard performance, and is made up of outside work at standard pace, machine-controlled time, and any portion of the relaxation allowance which has to be allowed

outside the machine-controlled time.



Unoccupied time allowance unoccupied time is calculated bysubtracting from the machine-controlled time the sum of all

periods of inside work in basic minutes, plus any part of therelaxation allowance which may be taken within the machine-controlled time.

Standard time is the total time in which a job should becompleted at standard performance.

Unoccupied time allowance is an allowance made to a worker when there is unoccupied time during machine controlled time.

Multiple machine work is work which requires the worker toattend two or more machines running simultaneously.

The load factor is the proportion of the overall cycle timerequired by the worker to carry out the necessary work at standardperformance, during a machine controlled cycle.



Machine interference Machine interference is the queuing of machines for attention — e.g. when

one worker is responsible for attending to more than one machine.

Interference allowance is an allowance of time for production unavoidablylost through simultaneous stoppages on two or more machines attended byone worker.

The diagrams for each machine are drawn one below the other, to the sametime scale. An example of an operator working three machines is shownbelow in figure.

Chapter-8 Work Study and Setting Time Standards for Machines

Documents

Transcript of Chapter-8 Work Study and Setting Time Standards for Machines