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Among machining processes, grinding has been used to achieve high dimensional tolerances and surface quality on workpieces. Yet, high levels of energy expenditure per volume of removed material and the need for cutting fluids make grinding one of the most environmentally impactful machining processes. Furthermore, changes in parameters such as grain and bond specifications of the grinding wheel, cutting speed, and specific material removal rate can lead to different productive and environmental results. Thus, the analysis of grinding processes should not be aggregated and leveraged into a single and broad output parameter. Instead, comprehensive study should be performed, in which the most relevant process parameters, inputs and outputs are considered. This paper presents a detailed study of grinding process, including the characterization of machine subunits and production modes, along with the use of a combined life cycle assessment hybrid model and real-time monitoring system to evaluate the consumption of energy, tooling, cutting fluid and compressed air. A detailed cradle-to-gate life cycle assessment study using eleven different impact categories and a productive performance assessment were performed to evaluate the effects on varying specific material removal rate and wheel type. For equal values of specific material removal rate, the change from a conventional wheel to a cubic boron nitride represented a power requirement increase of 19–24%. Cubic boron nitride wheel achieved remarkably better results on the wheel wear and part roughness indicators for all tested conditions. The environmental performance assessment showed a strict relation between the process environmental impacts and the consumption of electric energy and cutting fluid. To conclude, despite the higher power requirements, the combination of cubic boron nitride wheel with high values of specific material removal rate optimizes both the productive and the environmental results

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Life Cycle Assessment (LCA) is a well-established tool to analyze environmental aspects and impacts of products and processes. However, there are few studies available regarding LCA of automotive components such as the small parts used by vehicle engines, e.g., intake and exhaust valves. This paper showed a cradle-to-grave LCA of exhaust valves produced in Brazil for automotive use. Based on environmental hotspots of the case study, cleaner production scenarios were developed to reduce environmental burdens and to improve manufacturing eco-efficiency. Thirteen midpoint impact categories were evaluated and more than 90% of all the impacts were due to fuel consumption into the internal combustion engine during the valves use phase. Regarding the valves manufacturing phase, the machining processes applied on the valve stem represented 63% of all the impacts, and they were strongly influenced by the consumption of electric energy, raw materials used in the valve stem and cutting fluid. For this reason, cleaner production scenarios were evaluated and tested in a centerless grinding process of the valve stem. The best cleaner production scenario showed a potential impact reduction up to 72% in the standby grinding mode followed by up to 44% less impacts in the dressing mode. Simple changes on grinding parameters produced a huge potential of minimizing environmental burdens in a life cycle perspective, especially in terms of impacts for resources (fossil and minerals) depletion (RD). A comparison between the environmental profiles before and after adopting the proposed cleaner production measures showed a significant reduction of 27% on the RD impacts. Therefore, improvements of the exhaust valve's manufacturing parameters can generate a better environmental life cycle performance towards cleaner production.