Mathematical Models for Disassembly Line Balancing and Pickup - Delivery Vehicle Routing Problem

This study addresses the integrated disassembly line balancing and pickup-delivery vehicle routing problem of companies with multiple disassembly centers. In a supply chain with distributed disassembly centers, the products to be disassembled must be collected from the factories where they are supplied and brought to the disassembly centers. Then, these collected products must be disassembled in the disassembly centers and these disassembled components must be distributed to the factories that demand the disassembled parts. Since there are distributed disassembly centers, factories that request components and factories that supply products should be assigned to the disassembly centers. This study aims to provide an integrated plan for the assignment, disassembly line balancing and collection-distribution processes. In this study, there are distributed disassembly centers with limited product supplies, and distribution and collection operations are considered together in the vehicle routing problem. The problem differs from the studies in the literature with these features. The simultaneous collection and distribution operations aim to save time and reduce transportation costs of vehicles. A mixed-integer nonlinear programming model, a mixed-integer linear programming model and a constraint programming model are presented to solve the integrated problem. The performance of the mixed-integer linear programming and constraint programming models has been evaluated using small-sized instances, and the computational findings indicate that both models can provide effective solutions for the problem.