Research Reports from the Department of Operations

Document Type

Dissertation

Publication Date

1-1-1986

Abstract

The purpose of this dissertation was to provide a decision support system to address the capacity planning and operational design issues of a multi-product, multi-family, multi-stage serial flow production line. The existing algorithms find production schedules either for a single-product case or for a multi-product, single-family manufacturing system of only one stage. The latter problem is an NP-complete problem. The model developed in this thesis is called the Manufacturing Analysis System (MAS). MAS determines a feasible schedule that will minimize the total setup and inventory holding costs, which should be close to the optimal schedule. The Extended Basic Period (EBP) approach is used to determine a feasible schedule. With this approach, product cycle lengths are expressed as integer multiples (cycle multipliers) of a reference cycle length, called the Rotational Cycle. The product of the least common multiple of the cycle multipliers and the rotational cycle length is called the Horizon. Since each stage can have a different rotational cycle length and horizon length, the number of possible combinations for a multi-stage problem is infinite. Properties of an optimal schedule were determined, which showed that the horizons for each of the stages were equal. These properties also reduced the number of possible choices of schedule from an infinite set to a finite set. Further theoretical development reduced the maximum number of enumerations required per product from a polynomial function to a linear function in the number of stages. However, the theoretical work was developed in such a way as to recognize the realities of manufacturing environments. A hierarchical formulation was developed, which, along with the other theoretical work, made the model computationally feasible. This model was used to determine the schedule, after which a Closed Queue Network model analyzes the shop dynamics. MAS was validated by comparing the results of a multi-product, single-family, and single-stage problem against that of the existing algorithms designed specifically for the simpler problem. The solution from MAS was as good as that of the best of the other algorithms.

Keywords

Operations research, Production scheduling, Decision support systems, Project management--Mathematical models, Manufacturing processes--Planning, Production control, Manufacturing resource planning, Queueing theory, Mathematical optimization, Algorithms

Publication Title

Dissertation/Technical Memorandums from the Department of Operations, School of Management, Case Western Reserve University

Issue

Technical memorandum no. 567 ; Submitted in partial fulfillment of the requirements for the Degree of Doctor of Philosophy.

Rights

This work is in the public domain and may be freely downloaded for personal or academic use

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