Predicting cycle time distributions for integrated processing workstations : an aggregate modeling approach

To predict cycle time distributions of integrated processing workstations, detailed simulation models are almost exclusively used; these models require considerable development and maintenance effort. As an alternative, we propose an aggregate model that is a lumped-parameter representation of the workstation. The aggregate model is a single server with a Work- In-Process (WIP) dependent aggregate process time distribution and overtaking distribution. The lumped parameters are determined directly from arrival and departure events measured at the workstation. An extensive simulation study and an industry case demonstrate that the aggregate model can accurately predict the cycle time distribution of integrated processing workstations in semiconductor manufacturing.