Disassembly Lot Sizing Problem with Disposal Decisions for Multiple Product Types with Parts Commonality

Abstract

Abstract Disassembly lot sizing problem is one of the important operational problems in disassembly systems. It can be defined as the problem of determining the disassembly quantity and timing of the used-products to fulfill the demand of their parts over a finite planning horizon. This paper considers the case of multiple product types with parts commonality and the objective is to minimize the sum of setup, disassembly operation, and inventory holding costs. High inventory holding cost can be generated: because of disparity between independent and unbalanced demands, and the disassembly of one unit of used-product generates all the parts with different ratios. Aggregate formulation (AGG) can be used to model this problem by considering disposal decisions. Linear-Programming (LP) relaxation of this model doesn’t give very good lower bound, especially for the large-sized instances. We aim to improve lower bound of the problem. Facility Location-based formulation (FAL) is developed which can obtain optimal or near optimal solution by using LP relaxation approach. A two-phase heuristic is proposed which constructs an initial solution by using LP relaxation approach, and then improves by a dynamic programming based heuristic. Computational experiments are conducted on randomly generated test problems which show that the models and methods can give optimal or near-optimal solutions in very short computational times.