Analysis of cost effectiveness by material type for CO 2 saving and recycling rates in disassembly parts selection using goal programming

Abstract

To address issues such as global warming and material starvation, the manufacturing should be required to pay much attention to these environmental issues. Recycling is one of the effective methods to overcome both global warming and material starvation as it reduces CO2 emissions, one of the causes of global warming, at material production stage by means of material circulation. End-of-life (EOL) products require a disassembly phase for recycling in order to separate the parts into material types, which determine the choice of operations needed for recycling. Then, manual disassembly operations are carried out because of various complex disassembly tasks, thereby leading to higher recycling costs. In order to make recycling environmentally friendly and economical, selection of disassembly parts is conducted to minimize the recycling cost and to maximize the CO2 saving rate, which is defined as the rate at which CO2 volumes can be saved by material recycling instead of producing virgin materials. Thus, disassembly parts selection is considered as a multi-criteria decision making problem. Goal programming is well known as one of the effective methods to overcome the multi-criteria decision making problem. This requires setting of tolerable and sufficient targets for each goal. The material type of the selected parts is important for recycling process. Therefore, this study proposes a bi-objective environmentally friendly and economical disassembly parts selection for minimizing the recycling cost and maximizing the CO2 saving/recycling rates by goal programming, and analyzes the results in terms of weights and cost for each material type. First, a design procedure is explored and formulated using goal programming. Next, disassembly parts selection is carried out for maximizing CO2 saving/recycling rates and minimizing recycling cost. Finally, the results are analyzed to pursue the cost effectiveness for the recycled materials for each part in order to identify bottlenecks and propose improvement plans.