Modelling and scheduling of an asynchronous cyclic production line with multiple parts

In this study, we model and analyse a production line with asynchronous par t transfers, processing time variability, and cyclic scheduling in the same framework. We consider a production line with multiple parts and finite in terstation buffers. The line produces a batch of n jobs repetitively using the same order of jobs in every batch. The processing time of a job on a st ation is a random variable and is assumed to have a phase-type distribution . Parts are transferred between the stations in an asynchronous manner. We first present a continuous time Markov chain model to analyse the performan ce of this system for a given sequence. A state-space representation of the model and the associated rate matrix are generated automatically. The stea dy state probabilities of the Markov chain are determined by using a recurs ive method that exploits the special structure of the rate matrix. The cycl e time, the production rate, and the expected Work-In-Progress (WIP) invent ory are used as the main performance measures. We then present an approxima te procedure to determine the cyclic sequence that minimises the cycle time . We then investigate the effects of operating decisions, system structure, processing time variability, and their interaction in the same framework. Numerical results for the performance evaluation and scheduling of cyclic p roduction lines are also presented.