Controlling different flow rates in job-shop like production departments

The paper considers production departments where it is desirable that the production orders of different product types have different flow rates, independent of their production characteristics like processing times. Since flow rates are mainly determined by the work centre awaiting times the product types should have different production order waiting times at the work centres. The paper derives a method which makes this possible in a controlled way: given certain values for some parameters the different waiting times (and thus the flow rates) are predictable. By means of simulation this method has been tested for two production situations where, per work centre, only two different flow rates are required. In the first situation both (categories of) products have the same average routing length, whereas in the second situation the average routing length for both (categories of) products differ. This simulation study shows that, using a simple balance equation and operation due date sequence, it is possible to create different predictable flow rates. It turns out that up to a required waiting time reduction for one of the two (categories of) products of about 60% a one-to-one relation approximately exists between the scheduled (required) waiting time reduction and the, what will be called, normalized waiting time reduction.