A tactical planning model for a serial flow manufacturing system

Abstract

This project aims to improve the operation and planning of a specific type of manufacturing system, a serial flow line that entails a sequence of process stages. The objective is to investigate inventory policy, raw material ordering policy, production planning and scheduling policy, in the face of demand uncertainty, raw material arrival uncertainty and in-process failure. The tactics being explored include segmenting the serial flow line with decoupling buffers to protect against demand and raw material arrival uncertainty, and production smoothing to reduce production-related costs and the variance in upstream processes. Key policies for each segment include a work release policy from the decoupling buffer before the segment, and a production control policy to manage work-in-process inventory level within the segment and to meet inventory targets in each downstream decoupling buffer. We also explore raw material ordering policy with fixed ordering times, long lead-times and staggered deliveries in a make-to-order setting. A tactical model has been developed to capture the key uncertainties and to determine the operating tactics through analysis and optimization. This study also includes extensive numerical tests to validate the output of the tactical model as well as to gain a better understanding of how the tactical model reacts to different parameter variations.