A sortation system model

Automotive manufacturing is a complex task involving several steps of machining and assembly. Typically, larger components of an automobile such as the body, engine etc. are assembled over multiple systems. These large assemblies are transferred from one assembly system to another using conveyors. The conveyor/transfer system serves as a buffer and also serves to sort and re-sequence the components in a form that is required by the downstream operation. This requires the transfer system to be able to 'look ahead' at the requirements for the downstream operation and re- sequence the assemblies, if necessary. The sortation and re-sequencing part of the conveyor system is called a selectivity bank. The capacity requirement calculation and configuration design of these selectivity banks is difficult due to the randomness in the operation of, and the differences in schedules between the two systems it is connecting. Simulation is a valuable tool that is increasingly being used in the design, testing and upgrading of these systems. This paper presents the typical design issues of such selectivity banks, that are addressed using simulation. A case study is presented to elucidate the concepts and applications. The paper concentrates on automotive manufacturing systems but the concepts presented here are applicable to sortation systems used in several industries.