Why a system of motion analysis?
Measure is Pleasure,
Time is not the goal, it is the result
Why choose for
Time studies can be made with a stop watch and tempo rating. But then the following points should be taken into account:
The work to be studied must be really executed in practice.
Remark: - this is not always possible for new products in the developing stage
- a first series always entails a number of shortcomings
- in the beginning people need time to get ‘learned-in’.
There is practically always a need for a tempo and/or performance rating, based on a subjective judgement.
A situation is recorded at one specific moment as regards the time needed rather than as regards the method used or that could be used.
Measured time is hardly a guarantee that the operations performed during that time were indeed necessary.
Method study based on stop watch timing and tempo rating is very difficult to do and usually comes too late: for modifications afterwards to a product already in production or for modifications to production aids (tools and machinery) already in operation, will involve in that stage high costs and are often, in view of the series size, not profitable.
However, a system of predetermined (elemental) motion time analysis, like WORK-FACTOR is a system with which the method of an operation can be analysed beforehand into standard elements needed to carry out that operation:
The method and the time can now be determined before an operation is even started.
Method improvement (also beforehand) is now much simpler because the system provides a clear and thorough insight into the methodology and the possible alternatives.
At this stage modifications can be made without involving high costs.
The optimum method which, as said before, takes into account the possibilities of the working man can now be chosen and instructed to the operator in advance.
There is almost no subjective judgement, because methods A and B are compared with each other on the basis of the same standard elements which are all based on the same rules.
It can be calculated in advance, even at the stage of product-, tool-, and machine design, what improvements might cost, on the basis of possible savings on operating costs.
The normal time or basic time or standard time can be calculated because the intrinsic tempo of each of the WF systems is known.
It is the method to be adopted that is decisive for the cost of an operation, not the observed time.
The observed or recorded time gives little guarantee, as stated before, that the motions performed during that time were indeed necessary. Question: Were there really no surperfluous motions? Sure?
With method study as the starting point, all unnecessary motions are eliminated in advance.
Studying alternative work methods and the choice of the ‘optimum method’ that follows from it, automatically leads to the ‘most economic time’; in other words: time was not the aim, but the result.
So starting point is: Method study.
Of course, time remains an important measure of calculation for i.e.:
• valuation of performance
• task time or basic time
• build up times for standards
• allowances for R + PC
• allowances for small series
• capacity calculation
• line balancing and work tuning
• learning-in times
• work instructions
• performance assessment
• labour costs calculations
• production planning
• profit potency
Work-Factor Performance Pace has definite advantages over the various “normal” work-paces because:
Most experienced operators when fully motivated work at or near Work-Factor performance pace.
Work-Factor pace is more easily recognized.
Work-Factor pace is desirable economically.
Work-Factor System has definite advantages over other systems of predetermined times, viz.
At that time, 1952, an objective comparison of two systems was conducted viz. Work-Factor (DWF) and MTM (MTM-1). This was executed by very skilled and seasoned Work Study engineers who had been fully instructed in both systems during separate official courses and, who, in the opionion of their instructors, were qualified to practise in each system. The study was executed as follows:
A complete Detailed Work-Factor training program was pursued. A few weeks later the same group of engineers participated in a complete MTM-1 course. A six month study period followed. Several hundreds of operations were studied, these involved plants in and near London, Blackburn and Eindhoven. Conclusions were as follows:
Work-Factor (DWF) is more accurate and has the exclusive advantage of detail but can be made as simple as MTM-1, if so desired (SWF).
Work-Factor gives a better understanding of the difference between simple work and difficult work, by which a schoold worker can or may be better rewarded.
Work-Factor is a powerful tool in method study and motion study, also due to the relation of the elements with the time and hence with the basic times.
Work-Factor has a more complete set of specific and largely foolproof rules. MTM, especially for the elements of grasp and position/asemble leaves much to the judgement of the analyst.
Work-Factor provides a standard time as a yard stick which must or should be achieved.
Using Work-Factor it is easier to teach and conduct working methods and method improvement.
On technical points Work-Factor is prefered a.o. because of
- more variables for motion analysis
- generally has more thoroughly penetrated the special elements of motion analysis viz. simultaneous, surface
assemble, GD, TB and PB, etc.
- has a fewer/no number of debatable values in its tabular data
- has better/more allowances for weight
- takes care of many variations in motion patterns not recognized by MTM.