24.2.1 Select

To ensure maximum benefits from the effort put into the Method Study exercise, it is important to select appropriate situations. For example, there would be little benefit in conducting an extensive Work Study investigation in a situation where there was very little manual work and production was dependent mostly on the design of machines. Similarly, if the manual work was temporary or for any reason expected to be short lived, it may be impractical to carry out a full Work Study. However, situations where the duration of the work is short but repetitive, for example, maintenance work, will be suitable for Work Study. The economic results of the study, whether they are increases in output, reductions in scrap, improved safety, reductions in training time or better use of equipment or labour, should always outweigh the cost of the investigation. This maximum cost benefit should not only be sought after by looking at direct costs, but should also be looked for in the indirect cost areas. The human factor should always be considered; thus not only areas where there is apparent wasted time should be studied, but also areas where there is high labour turnover and absenteeism.

24.2.2 Record

There are many recording techniques available for the modern Work Study practitioner. Factors that influence the choice of technique are the rapidity with which the record has to be taken and the amount of detail desired. When first investigating a situation, one of the broad rapid techniques might be used, but as the necessity for examining the detail of the job becomes more important a more time consuming technique may be necessary. Tools such as video cameras are ideal for making permanent records of work for future analysis. Integral digital time displays assist the practitioner to determine durations of work elements. High speed and time lapse photography can also be used. To change the visual record of a job into a form suitable for further analysis, techniques using charts and tables are used. Examples of some industrial problems and their relevant recording techniques are now briefly described.

• The techniques associated with plant layout, such as flow and string diagrams, templates, three‐dimensional models and travel charts. Some of these are illustrated in Figure 24.2. They are suitable where large scale movements and areas are being examined without requiring detail to be analysed.
• When the activities of one or more men and/or machines are being examined, then multiple activity charts, activity analysis, or operator and machine charts can be used (see Figure 24.3).
• Process charts. There are many variations of these, for example, the outline process chart, the flow process chart and the two‐handed or operator process chart. These are the most common of the Method Study recording techniques, the sequence of events being represented by a series of symbols that are basically the same for each type of chart. Figure 24.4 shows a clevis assembly chart that uses the clevis rod from Figure 22.7.
• Where long or irregular work cycle times occur, and where studies of groups of workers are required, then memo‐motion photography or work sampling may be employed. In this technique, movements are recorded using a video camera set to take pictures at longer than normal intervals. It is therefore a method of sampling, as activities are observed at regular intervals rather than continuously. When the recording is played back at normal viewing speed, patterns of movement unnoticed in real time often become apparent. Passenger movements in airports and rail stations, the movement of ships in rivers and the flow of customers in large shops or post offices are typical applications of this technique.
• Cyclegraphs are recordings of the paths followed by moving objects obtained by attaching light sources to the objects and photographing the scene using a time exposure camera. The effect is observed by taking a time exposure at night of a city traffic junction. The paths taken by the vehicles using the junction are observed as continuous paths of light on the final print. This effect is utilised by attaching lights to operators' wrists and observing the paths travelled during a particular piece of work, for example, folding a shirt in the garment trade. By rapidly pulsing the lights on and off for specific periods the resulting traces will show up as broken lines. These are known as chronocyclegraphs and by counting the pulses the length of time for each movement can be found.
• When the work movements to be recorded are so complex or fast that the other techniques are inadequate, then SIMO (Simultaneous MOtion cycle) charts are often used (see Figure 24.5). To facilitate the detailed study required, the fundamental movements which together constitute all types of manual work are classified and identified by the use of ‘Therbligs’ (the name ‘Gilbreth’ reversed, see Figure 24.6). The use of these ‘Therbligs’ in conjunction with SIMO Charts is referred to as ‘Micromotion Study’. By using high speed video techniques, complex and intricate finger and hand movements can be filmed and observed in slow motion or frame by frame, and from these observations the SIMO chart can be drawn.

24.2.3 Examine

In this stage, the information recorded is constructively analysed by systematically questioning each activity observed. Assuming that here we are concerned with a manufacturing task, then the recorded activities will fall naturally into two main categories: (i) those in which the material or workpiece is being worked upon, moved or examined and (ii) those in which it is not touched, as it is either in storage or at a standstill owing to a delay. The activities in category (i) may be further subdivided into three groups: (a) ‘Make Ready’ activities, (b) ‘Do’ operations and (c) ‘Put Away’ activities. Thus while ‘Make Ready’ and ‘Put Away’ activities can be represented by ‘transport’ and ‘inspection’ symbols, ‘Do’ operations can be represented only by ‘operation’ symbols. The object of the exercise must be to achieve as high a proportion of ‘Do’ operations as possible, since these are the only ones that carry the product forward in its progress from raw material to completed product. These are ‘productive’ activities and ‘add value’ to the product; all others, however necessary, may be considered as ‘non‐productive’.

There is a well‐established questioning sequence which examines the purpose, place, sequence, person, and means of the activities. This has the aim of eliminating, combining, rearranging or simplifying them. The questioning technique can be set out as follows.

• WHAT is done?
• WHY is it done? What else might be done? What should be done?
• WHERE is it done? Why is it done there? Where else might it be done? Where should it be done?
• WHEN is it done? Why is it done then? When might it be done? When should it be done?
• WHO does it? Why does that person do it? Who else might do it? Who should do it?
• HOW is it done? Why is it done that way? How else might it be done? How should it be done?

These questions are the basis of a successful Method Study and should be asked, in sequence, every time a study is undertaken.

24.2.4 Develop

Just as in the ‘Examine’ stage, there is a methodology for implementing the ‘Develop’ stage. It consists of four steps: eliminate, combine, sequence and simplify. It is applied to each separate activity in the job, that is, each meaningful group of work elements.

The total elimination of unnecessary actions is obviously the first and most important step towards an improved work method. These redundant activities can arise due to changes that have occurred in the product or bad work practices that have gradually been adopted. Once the possibilities of elimination have been exhausted, the combination of actions must be considered, for example, parting off a component in a lathe and facing the following component simultaneously. Next, the opportunities for changing the sequence of actions must be examined, with a view to subsequent further elimination and combination. Finally, if additional improvements are still required then the more costly simplification of the activity may be necessary. This can be done by reducing the number of operations and optimising delays, storage and transportation.

To facilitate simplification, the ‘Principles of Motion Economy’ can be used. These are rules, originally formulated by the Gilbreths, that help ensure that a job will be carried out with the minimum of effort and the maximum achievement. Essentially, they state that work should be designed so that movements are minimised, simultaneous and symmetrical (e.g. two hands working in unison at an assembly task), rhythmical, habitual and continuous.

Once the steps of elimination, combination, sequencing and simplification have been completed, some additional experimental and practical adjustments will probably have to be made. When the practitioner is finally satisfied with the method the last two steps can be implemented.

24.2.5 Install

Due to the human element the steps of installation and maintenance of the method can often be the most difficult. Active support of the practitioner by management and the workers involved is essential. The practitioner should be able to explain clearly and simply what he or she is trying to do, and he or she must have the ability to win the trust of all those affected by the study.

Installation can be divided into five stages:

1. Gaining acceptance of the change by the departmental supervision.
2. Gaining approval of the change by works and general management.
3. Gaining acceptance of the change by the workers and their representatives.
4. Retraining the workers to operate the new methods.
5. Maintaining close contact with the progress of the job until satisfied that it is running as intended.

24.2.6 Maintain

To ensure the new method is maintained it should be monitored by the Work Study department. This is because human nature is such that a drift away from the method will probably occur if there is no check. Many disputes over time standards arise because the method being followed is not the one for which the time was specified: foreign elements have crept in. If the method is properly maintained, this cannot happen. If it is found that an improvement can be made in the method, then this should be incorporated officially, a new specification drawn up and new time standards set.

Now that the most appropriate method for doing the work has been established, it is necessary to establish the times required to complete the work elements.

24.3.1 Basic Procedure

As with Method Study so also with Work Measurement a systematic approach is necessary. The steps of this are as follows:

• Select the work to be measured.
• Define the methods to be used. Break the job down into elements. Critically examine the recorded data and the detailed breakdown. This will ensure that the most effective method is being used and that unproductive elements are separated from those that are productive.
• Measure the quantity of work involved in each element, in terms of time, using the appropriate direct or indirect work measurement technique.
• Obtain the total work content plus any allowances.
• Establish the Standard Time for the operation, which will include the time allowances to cover relaxation, personal needs, contingencies and so on. It must be ensured that the series of activities and methods for which the time has been compiled, is defined. Finally, the time will be issued as standard for the activities and methods specified.

24.3.2 The Standard Unit of Work

The concept of using a unit for measuring work is founded on the notion that the human work content of many different types of job can be expressed quantitatively in terms of a common unit. Some terms used by Work Study practitioners in connection with this concept are given next:

• Standard Performance. This is the rate of output at which qualified workers will naturally achieve without overexertion as an average over the working day or shift, provided they adhere to the specified method and provided they are motivated to apply themselves to their work.
• Standard Unit of Work. This is composed of both work and relaxation, the proportion of each varying with the nature of the job. In the British scale, 60 of these units would be created in one hour of unrestricted work at standard performance (standard performance is explained in the Section 2.3.3.1 ‘rating’).
• Work Content. This comprises the basic time and relaxation allowance plus any other allowance for additional work.
• Standard Time. This is the total time that should be required to complete a job at the Standard Performance. This will be composed of the total Work Content plus allowances, plus any other time that may have to be added for delays and other unoccupied time.

Thus, because the unit of work represents a specific amount of work plus allowances, it has no absolute time value. However, since it must be given some relevant dimension, a figure of 60 units of work per hour at Standard Performance may be adopted. These units are called ‘standard minutes’, so that if one unit of work is carried out at standard performance then it will be completed in one minute of time.

24.3.3 Time Study

Time Study is normally required when there has been a change in the nature of an existing job, or a new job has been started: remember that Time Study should not be attempted until a proper Method Study has been carried out. Time Study is a work measurement technique used for recording the times taken and the rates of working, under specified conditions. It can then be used to establish the Standard Time for the job.

Time scales used when conducting the study may be seconds or decimal fractions of a minute, the latter being the more common and precise. Other time scales, for example, decimal hours, can be used but only in special circumstances.

Traditional Time Study equipment includes a stopwatch, a Time Study board and forms. Video cameras may be used in which the precise timing of the activity is displayed to enable accurate separation of work elements and establishment of their times.

24.3.3.3 Allowances

After the Basic Time has been calculated there is one further step required before a fair Standard Time can be allocated to the job. This involves the allocation of allowances to compensate for the operator fatigue, delays and interruptions that are unavoidable in every work situation. These allowances are composed of the following elements: (i) A Relaxation Allowance to allow the operator to attend to personal needs and to recover physically and mentally from exertion; this may add 10–30% onto the Basic Time, depending on the nature of the work. (ii) Unoccupied Time, which occurs when the worker is unavoidably prevented from doing productive work; this should obviously be minimised if it cannot be eliminated. (iii) A Contingency Allowance to cater for occasional interruptions, adjustments to equipment and so on.

It is now possible to devise the Standard Time for the work that, as mentioned previously, is the total time in which a job should be completed at standard performance; it is shown schematically in Figure 24.7.

The foregoing sections have shown how it is possible to use Method Study to determine the most efficient way of carrying out a job, and then to use the Work Measurement technique of Time Study to establish the Work Content and Standard Time.

There are other techniques used in Work Measurement. Another direct measurement technique is Activity Sampling. Here the work is not measured using a timepiece; it is sampled. Activity Sampling is used in situations where it is desired to measure the work of large amounts of people, say in an office. Over a period of time a large number of individual observations are made. At each observation a record is made of what is happening at that moment and the percentage of the observations recorded for a particular activity is taken as representing the actual time during which that activity occurs.

Indirect Work Study techniques include Estimating and PMTS. Estimating is a technique used for determining the time required to carry out a job by using knowledge and experience of similar work done previously. PMTS is a technique that uses times previously established for basic human motions. This synthetic method allows times for jobs to be built up even before the work has started. There are many varieties, but one of the most popular is Methods Time Measurement, which has been developed at three levels. MTM 1 is the most accurate and detailed; it will also take the longest time to implement. MTM 2 is used where the detail of MTM 1 would economically prevent its use. MTM 3 is intended to be used in work situations where at the expense of some accuracy times are required as soon as possible.

24.4.1 Labour Control and Reporting

The information coming from the shop floor to the management must be sufficiently detailed to identify specific areas of poor performance, unproductive work or excessive cost. How this is done is best understood by following the process through progressively.

Throughout the day the shop floor workers will spend their time either directly on work for which there is a Standard Time, on diverted work such as repairs or on waiting for material or equipment. Only the direct work is productive and adds value to the product. The operators will record, by writing on report sheets or keying into a computer, how they have spent their time each day. This record will show what products and operations were worked on, how many were produced and how much time was spent on direct and diverted work. It should be noted at this stage that although terminology varies between countries and even factories, the concepts remain the same. Indirect workers such as labourers will also submit reports detailing how they have occupied their time during the day.

From these reports the data processing department will be able to compare the times the operator spent on specific operations against their previously devised standard times. It will then be possible to provide management with information on the performance of the direct operators, the performance of a department excluding the indirect workers and the overall performance that will include all the workers on the shop floor. A breakdown of how the unproductive time was spent will also be supplied; this will enable problem areas to be pinpointed.

The performance figures will probably be supplied in a similar manner to the following:

A short example illustrates the use of these indices.

During a five‐day week a department reports the following information.

Calculate the overall performance, the departmental performance, and the operator performance.

Total Attendance Time = 7.5 × 5 × 20 = 750 hours.

A detailed report on performance is therefore provided to the management and supervisors. This would normally be supplied to shop floor supervision, for example, foremen, on a daily basis on the day following that on which the work took place; this will enable prompt corrective action to be taken. The supervisor will receive a full report on each individual operator and a composite report for the performance and time utilisation for his department as a whole. Reports will probably be summarised on a weekly basis for line management and factory management will probably receive weekly or monthly reports as appropriate. Action should be taken immediately on the reports, for example, low operator performance needs prompt investigation, as also do instances of high rework or other diverted time. Communicating productivity data to the shop floor is also important. Charts showing various performances for each department can be erected in prominent locations. Charts of quality, for example, reject rates and costs of scrap, are also useful.

24.4.2 Payment by Results (PBR)

In this type of payment system the workforce is usually paid a basic rate plus an amount proportional to performance. This may be on an individual or a group basis. It is apparent that the type of performance indices shown in Section 24.4.1 provide useful data on which to base such systems.

24.4.3 Planning

Since Work study provides a data base of information on how long specific operations should take, the total time required to build products and the methods and equipment required to produce specific quantities of a product, it can be used to predict future manpower and capacity requirements based on anticipated product sales volumes. The total standard times involved in a product can simply be multiplied by the anticipated weekly production target to find the total standard times required per week. This can then be related to the overall performance the factory or departments are achieving to arrive at a total time required for the anticipated production volumes. Knowing the total man hours available per week, this total time can then be used to determine the required manpower.