Sensitivity analysis of dry machining using a Life Cycle Assessment approach

Manufacturing processes, particularly machining operations, contribute significantly to the environmental footprint of the industrial sector, primarily driven by the consumption of critical resources such as lubricants, tools, and electrical energy. However, the large number of machining parameters and the difficulties of modeling industrial products have always limited analysis of the environmental impact of the process. This study aims to provide a comprehensive understanding of the environmental impact during dry machining. The overarching goal is to contribute to the development of strategies to mitigate the environmental consequences of these manufacturing processes. To achieve this objective, a Life Cycle Assessment (LCA) was conducted to quantify and analyze the environmental impact, using the Environmental Footprint 3.0 calculation method. The central idea is to highlight the often-underestimated contribution of tool wear to the overall environmental impact of the machining process, whereas in the literature electrical energy is the most studied source of consumption. The methodology involves an analytical model, and an experimental test designed to quantify the resource consumption, with the conduct of a sensitivity analysis to determine the machining parameters and scenario influence on the distribution of environmental impact. While electricity consumption traditionally dominates discussions of environmental impact in machining, results of the study reveal a significant contribution from tool wear in the environmental impact ratio, according to specific environmental indicators. The preponderance of this contribution is favored when the values of cutting conditions or tool radius /number of teeth are increased. Depending on the values of the cutting conditions, the scenario and the environmental indicator, the proportion of tool wear in the environmental impact ratio can vary from 5% to almost 90%. In terms of global environmental impact, cutting speed is the most influential parameter, varying by more than 2 times the minimum value for each environmental indicator. A precise definition of the scenario and consideration of the machining parameters are therefore essential to assess the environmental impact of machining correctly. This study also underscores the importance of considering tool wear in the environmental impact of dry machining, which plays an important role depending on cutting conditions, especially cutting speed.