Optimal design of a hybrid push/pull serial manufacturing system with multiple part types

The objective of this research is to investigate the possibility of integrating Manufacturing Resource Planning (MRP)/push and Just in Time (JIT)/pull strategies in a multiproduct multistage serial manufacturing system. Each workstation is able to undertake different operations and so to produce more than one type of in-process item. A modified version of a horizontally integrated hybrid push/pull production system is developed. The system can be optimized by locating points of integration, and determining the optimal values of safety stocks for the push part and numbers of Kanbans for the pull part. A modification of genetic algorithm (GA) chromosomes and crossover procedures is developed for the optimization. The optimization involves evaluations of stochastic performance measures by a discrete event simulation model. The motivating case study of a tube shop in an aerospace manufacturer is presented. This research extensively explores the question of whether each part type should have its own junction point (less constrained) or whether there should be one common junction point for the overall system (easier to implement).