A Study on the Performance Characteristics of Closed-loop Asynchronous Automatic Assembly Systems

摘要

An automatic assembly system, a key tool for mass production, is generally composed of a number of workstations and a transport system. While the workstations perform some preplanned operations, the transport system moves the assemblies from one station to another. Usually an assembly is moved on an especially designed cartier called a pallet. The device that fixes the position of an assembly on the pallet is called a fixture. A typical example of automatic assembly systems is a disk washer assembly system which consists of more than forty stations. The complexity of analyzing the performance of an automatic assembly system is that the overall performance is affected by many factors. These factors include: (i) the number of stations installed (ii) the number of pallets installed (iii)) the buffer units between two stations (iv) the reliability of the workstation (v) transport delay time. Therefore, one of the major challenges to a design engineer is to find the optimal combination of the mentioned factors while maintaining the highest productivity at a lowest cost. A simulation model written in C++ is particularly designed to study assembly systems with different configurations. In our study we first use this simulation model to study the performance characteristics of closed-loop assembly systems. The impact of each decision factor on the overall performance is also analyzed. The optimal configurations were then identified. Finally, the guidelines for optimizing the overall performance of automatic assembly systems are provided.