The purpose of work measurement is to determine the time it ought to take to do a job. The problem is in the definition of “ought to.” Work measurement analyst define this as the time it should take an experienced and well-trained operator to perform the job in a specific and well-defined method at a speed that can be maintained all day, day after day, without undue fatigue. This time, called standard time, can be divided into several parts: the actual elements used to perform the job; the rating factor used to determine the “normal” pace of these elements (the method used to determine the “ought to” time); and an allowance for personal time, unavoidable delays, and slowing due to fatigue.
There are four main systems of work measurement. First, and most used, is time study, specifically, stop-watch time study. Motion picture and video cameras, computers, and various production timing devices can also be used in the place of, and in conjunction with, the stop watch. The second system, work sampling, is a statistical procedure for measuring work and requires an understanding of the techniques of statistics and probability.
The third system, predetermined time systems (PDT), uses sets of tables of basic motions that have already been “normalized” by experts. Thus, PDT systems do not require the analyst to “rate” or “level” the measurement. Finally, there is the standard data system of work measurement which, strictly speaking, is not a measurement technique at all. Here similar elements made up of similar groups of motions from the other measurement systems are tabled and then reused as needed for subsequent products and standards.
USES OF WORK MEASUREMENT
Work measurement is used to determine standards against which comparisons can be made for a variety of purposes.
1. Wage incentives. If workers are to be paid in accordance with the amount of work accomplished rather than the amount of time expended (hourly), some means of determining an acceptable, or fair, amount of work is needed. The payment for work accomplished could be based on sales price and profits, but a fairer method is to establish a standard and pay in accordance to that standard.
2. Schedules. In order to schedule work effectively and keep things running smoothly and orderly, a knowledge of expected working times is an absolute necessity.
3. Budgets. Budgets provide needed control over funds. One of their more important inputs is operating costs. Standards provide the expected operating times from which these costs are computed.
4. Labor cost control.Labor cost is usually a very significant percentage of the total manufacturing cost (normally from 10 to 40 percent). To control these costs, the actual costs must be compared to a standard and any deviation corrected, especially if the actual is greater than the standard.
5. Downtime studies. Properly developed standards include reasonable allowances (extra time) for personal time, unavoidable delays, and fatigue. Both time study and work sampling can be used to determine these allowances. They can also be used on a continuing basis (daily or weekly) to measure actual downtime and personal time when definitive production records are not kept and standards are not used.