Remanufacturing Process Optimization - Introducing Dynamic New Part Infill to Increase the Utilization Rate of Remanufactured Components for Multi-Variant Cores

Climate change, resource scarcity, and the current energy crisis demand fundamental change to overcome future problems. The Circular Economy represents a sustainable process transformation by closing value chain loops. Remanufacturing is one method that extends the life cycle of materials by returning worn-out products (cores) to the manufacturer to produce like-new remanufactured products. In detail, cores are disassembled into core components, which are inspected, sorted out, cleaned, remanufactured, and reassembled into a remanufactured product. The challenge is that multiple components in different conditions must be combined into one remanufactured product because only a certain quantity of core components can be used for remanufacturing due to quality criteria (yield rates). The cores' uncertain quantity and different yield rates of core components limit the maximum amount of remanufactured products, and the component with the lowest quantity acts as the bottleneck. In other words, although the rest of the parts have been remanufactured through costly and time-consuming processes, they remain unused, and the output of newly remanufactured products is obstructed. Such inefficiencies must be reduced to increase efficiency and create a sustainable process. This paper proposes a problem formulation and a concept that optimizes the utilization of remanufactured components in remanufacturing processes by modifying the bills of material of remanufactured products. The concept implements a dynamic infill of new parts, applying a dynamic mixture of new and remanufactured components to increase the number of remanufactured products while following technical and process restrictions (e.g., production and material planning, quality requirements). The utilization problem is identified as a combinatorial optimization problem and translated into a general multidimensional knapsack problem. The resulting knapsack problem is optimized with a meta-heuristic to find a satisfying solution for the utilization of remanufactured components. Following the case study methodology, the concept is developed, tested, and validated with an automotive OEM.