Mixed Model Production Manpower Calculation

In this competitive environment running one type of product in the same assembly line using same manpower group will not be economical, since there may not be much order for running the line for whole shift or day. So in that situation we need to run different products in same assembly line with little bit changeovers, so that we can reduce the space consumed and reduce the cost. Hence the importance of mixed model production manpower calculation come in to picture.

The formula in the picture gives the manpower required per shift for producing no of product P and o no of product Q per day. t and u is the total standard man minutes required for producing one P and Q respectively. w is the working time of an employee per shift and s is the no of shifts per day. Please note that this formula is only applicable where enforced idle of the operator is not present in the operation. Enforced idle means the operator is forced to be idle due to some other reasons of his working environment. For example, some operators of the balanced assembly line will be idle to some extend, especially the operator at the operation which has the lowest cycle time, waiting for his turn. This is not avoidable because we cannot balance the assembly lines at 100% perfect. For calculating manpower for balanced assembly line there is another method and I will explain in line balancing.Its better to consider 85% efficiency in the manpower calculation for getting the practical results. This efficiency is accounted for loses such as power failure, material shortages, speed loses, rework, defects, etc.

Example of manpower calculation