Simulation-based scheduling of assembly operations

The production of large-sized machines or facilities is fundamentally different from the usual manufacturing processes. Mostly it is a fixed-site production, dominated by typical assembly processes instead of linear operation sequences in the known flow shop or job shop problems. To describe these processes, several graph methods were developed in the past, i.e. AND/OR-graphs or modified Petri nets, but most of them are static methods and they are not suitable for scheduling tasks. This paper demonstrates how Timed AND/OR-graphs can be modelled with a common discrete event simulation (DES) system. The objective is a simulation-based scheduling system for assembly processes which is able to improve the prediction of due date keeping as well as to optimise the workflow of the assembly systems.