Sustainability Evaluation and Process Optimization of Mechanical Manufacturing Systems Based on Emergy Theory

Abstract

To address the sustainability challenges faced by the machinery manufacturing industry, this study establishes an emergy-based evaluation framework that integrates four dimensions—economic, social, ecological, and sustainability—to comprehensively assess the sustainability of mechanical manufacturing systems. An empirical study was conducted on the balance shaft housing manufacturing system of AH Axle Co., Ltd. Results reveal that the system exhibits a relatively low net emergy yield ratio (NEYR), with an emergy investment ratio (EIR) of 2.27 and an improved emergy sustainable index (IESI) of 0.44, indicating poor social benefits and weak long-term sustainability. However, through the optimization of finishing and casting processes, the emergy waste rate (EWR) decreased from 12.96% to 9.86%, substantially enhancing overall sustainability. This study not only provides a novel perspective and practical tool for sustainability assessment in mechanical manufacturing systems but also offers significant theoretical and practical implications for promoting green transformation and sustainable development across the industry.