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

Situation : A customer wants a product P and another or same customer wants a product Q at the rate of 5000 units and 8000 units per day respectively. The product P have three operations A, B & C, which requires man minutes 5, 8, 6 respectively. And the product Q have two operations D & E, which requires man minutes 9 & 11 respectively. The company works for two shifts per day and working time per employee is 420 minutes. Normal efficiency of the operations of the company is 85%.

Calculation:

Demand of P per day (n) = 5000

Demand of Q per day (o) = 8000

Man minutes per product P (t) = 5 + 8 + 6 = 19 man minutes

Man minutes per product Q (u) = 9 + 11 = 20 man minutes

Working time per employee (w) = 420 minutes

No of shifts per day (s) = 2

Manpower required per shift = (((5000 * 19)+(8000*20))/420)/2

= (((95000)+(160000))/420)/2

                                               = 303.57

Manpower required per shift considering 85% efficiency = 303.57/.85

                                                                                            = 357.14

                                                                                            = 358 nos

So in this situation this company needs 358 peoples per shift for satisfying its customer demand (716 peoples per day).

Please note that, if any equipment are using for these operations we need to do capacity analysis for the equipment before recruiting the peoples, otherwise if there is no enough equipment these manpower will be idle. I will explain the capacity analysis in another post. 

In this calculation, its assumed that the change over time is included in the 15% efficiency loss.

We have prepared a mixed model manpower calculator, so that you only needs to enter values for ‘mixed model production manpower calculation’. The result will be displayed in matter of a click. Have a look !!!.

Thank You for reading.

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