Type-E disassembly line balancing problem with multi-manned workstations

Recovering the end-of-life (EOL) products helps companies reduce the purchasing cost for goods and materials that can be removed from EOL products and reused. This also contributes to the efforts aiming at reducing the environmental consequences of hazardous materials. Disassembly lines play a vital role in the disassembling process of EOL products. This research introduces the Type-E multi-manned disassembly line balancing problem and proposes efficient linear and non-linear models to solve the problem. The main contribution of this work is the simultaneous optimization of the two conflicting objectives, i.e. cycle time and the number of workstations to maximize the efficiency of disassembly lines. Another contribution of the work is that the workstations may operate in a multi-manned environment (with more than one worker in a workstation) in certain conditions to maximize the line efficiency. The problem is defined and modelled mathematically. Numerical examples are exhibited to illustrate the solutions for problems. A comprehensive computational study is conducted to solve the test problems using the proposed models and the results are compared to the literature. It is observed that handling the Type-E objective provides a clear advantage to maximize the line efficiency. Furthermore, allowing the multiplication of the capacity of the workstations help improve the line efficiency enormously. This is thanks to the increased opportunity in the process of assigning tasks to workstations.