Synthesis is a Work Measurement technique which builds up Standard Times using data obtained from previous Time Studies.
Synthetic data are used to establish the work content for job and batch production work and also for other work of a repetetive nature. It is an extremely valuable technique in estimating time standards for production planning and estimating in connection with quotations.
Two Important Considerations
Before any time established in one situation can be used in another, it is vital to ensure that conditions are identical or that, if there is a difference in condition, it can be assessed accurately;
The calculations involved in applying Synthetic Data should be straight-forward and easy to understand. Systems which are so complicated that only the originator can understand them, or which take longer to calculate than would timing the job in a conventional manner, defeat the whole purpose of synthesis. It is also important that the method of arriving at standard times from synthetic data should be understood by foreman and operatives, who might naturally be more suspicious of synthesis than of direct measurement.
Times built up from synthetic data fall into two main categories:
- Element Times
- which can be assembled to form job times, used where accuracy equal to that of time study is required;
- Job Cycle Times
- where such accuracy is not needed, i.e. painting, maintence work.
There are three types of synthetic elements:
- Identical Elements
- e.g. "place in fixture" which may emerge as the same time, within narrow limits, for every component in a certain range. The important thing here is to take a sufficiently large number of studies to be sure that the identical element is correctly identified;
- Similar Elements
- which vary by some definite characterstic. Here, sufficient studies must be taken to ensure that the characterstic has been determined and that a graph can be made, plotting time against the characterstic. An example would be in painting when, with all else equal, the width of brush plotted against time gives an even curve on a graph (Currie page 168);
- Machine or Process Controlled Elements
- where time can usually be determined from machine or process data.
N.B. It is recommended that, for synthetic purpose, Basic Times should be used (i.e. times at BSI 100 performance, excluding allowances). The latter should be assessed as in time study.
Advantages of Synthesis
- Data from many studies is more likely to be accurate/reliable than that from a few;
- Once established the use of synthetic data means that less time of measurement personnel is spent on routine direct observation, thereby releasing skilled resource to other important duties;
- It is claimed that the use of synthesis over direct observation can yield a saving of up to 90% of the cost of direct observation.