A multi-criteria decision method for sustainability assessment of the use phase of machine tool systems

In recent years, going green has become a strategic priority in manufacturing which has evolved from the growing awareness of the need for environmentally friendly processes and products. Recent trends in developing new machining strategies able to support environmental protection and prevention of pollution in balance with socioeconomic needs and technical requirements inevitably require significant efforts in fundamental understanding of the actual energy and material flows needed to meet the machining requirements. This paper describes the methodology and software, Global Reasoning for Eco-Evaluation of Machining, developed to evaluate the use phase of a machine tool system with respect to a consistent set of technical, economical, and environmental criteria, as a part of the NEXT European project. The evaluation, based on the analytic hierarchy process, is conducted at two levels: (a) the process/part level which considers the local cutting environment along with the actors that are directly involved in the cutting area, their relationships, and the phenomena that occur from their interactions and (b) the system level which gathers together the main specifications of the machine tool system and the energy requirements associated with various activities performed in order to support the material removal processes. Two database structures were defined in order to store the entire amount of data needed to perform the analysis at each level. A detailed example of the evaluation carried out at the first level demonstrated the superior performance of the dry and minimum quantity lubrication alternatives over their wet machining counterpart when cutting power, cutting fluid consumption, and the machining time were considered as criteria for the performance evaluation of various milling tests.