New features of the cyclic job shop scheduling problem

This paper reports recent findings for so called cyclic production systems, which provide constantly on the system output the fixed mixture of various goods produced in a short series. Analyses are made for a general structure of manufacturing system, represented by so called cyclic job-shop scheduling problem. Starting from our achievements developed already for classical job shop batch systems occurring in OR field, we extend the approach to cover cyclic manufacturing strategy. We focus on the modelling aspect by using combinatorial representation of a solution with the support of unique class of graphs. The approach differs significantly from few appeared so far in the literature. We discuss new properties useful in finding the minimal cycle time for fixed (given) job processing order on the base of graph paths as well as special features of the problem. Originality of this approach derives from the analysis of paths in a graph. Based on the detected special properties we propose an approximate algorithms with promising numerical results.