Section 21` Repetitive Production that Passes Through Multiple Work Centres

Manufacturing Corner on

Monday, November 28, 2022

Repetitive Production that Passes Through Multiple Work Centres In the example in Section 20, the 1st operation of a job had to be complete before the second operation could start. However if the job is to manufacture 5000 units, then often you don't have to wait for all of them to have gone through the 1st operation before you start the 2nd operation. When the first transfer batch (pallet load or bin full) of the product has come off the 1st work centre, it can be passed to the second work centre for the second operation to start while the product is still going through the 1st work centre. 

 A similar principle will apply at the end of the production run, when the last transfer batch (or part batch) of product comes off the first operation it will join a queue at the second operation. However if the second operation is faster (as in this example), then the first operation will stop, the transfer batch will be passed to the second operation, which will then stop after the transfer batch has been completed. The rule that defines how long after the 1st operation the 2nd operation can start and stop, should be stated as the number of units in the transfer batch, but for the sake of simplicity, we will define it here as the time which the start and stop, of the next operation, lags behind the previous operation:

Although the second operation can start 1 hour after the first, it is faster and will quickly catch up. Work Centre 7 will then keep stopping to wait for products from the slower Work Centre 6,

and that is why the effective speed in units per hour is so much less than the  rated speed. This is a typical "PUSH" schedule, but we discuss an alternative approach in later sections.

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