Modeling validation and control of manufacturing systems

In this paper we elaborate on the problem ofsupply chain control in semiconductor manufacturing. First,we introduce the problem. Next, we propose the use ofEffective Processing Times (which can be measured fromreal factory data) to arrive at ‘simple’ discrete-event modelsfor manufacturing systems. We explain why existing modelscan not be used for solving the problem and explain theneed for PDE-models that consider the flow of products asa compressible fluid flow. Next, we present a validation studyin which we compare the response of the currently availablePDE-models to the results of discrete-event simulation. Weconclude the paper by analytically deriving a controller thatsolves the ramp-up problem. The resulting controller is oftenused in practice.