Batching and sequencing of jobs with order availability at a single facility

A single facility scheduling problem concerned with the production of jobs in a set of customer orders is analysed. Each order consists of several jobs. Based on the concept of group technology, jobs can be grouped into different classes. Jobs in the same class can be processed together in a combined batch, where batches of different classes are initiated with a setup time. Further more, the order availability is assumed, which means the finished jobs of an order cannot be shipped out to its customer until all other jobs in the same order have been completed. Under the above production environment, a branch-and-bound algorithm is developed to determine a schedule with the minimum mean flow time of orders. A heuristic is also developed to solve large-sized problems. Computational results of both approaches are reported.