Lot Streaming in Hybrid Flow Shop Scheduling

Production planning and scheduling play significant roles in manufacturing system operations and different techniques have been used to enhance their performance. Lot streaming has been studied for decades and is shown to accelerate production flow. This research deals with lot streaming in hybrid flow shops. Multiple products are processed in a multi-stage hybrid flow shop with non-identical machines. Sublots can be constant or consistent and intermingling is not allowed. Setups are attached and sequence independent. The problem is to simultaneously determine product sequence and sublots sizes so that the makespan is minimized. The model presented in this thesis is a mixed integer linear programming formulation for solving this problem. Several variations of the model are presented to incorporate different problem settings such as exploitation of variable sublots in the single product problem. Numerical examples are presented to validate the proposed model and to compare it to similar example problems in the literature. Furthermore, an example of a lot streaming problem in a general multi-stage hybrid flow shop is concerned and discussions and analysis are presented.