In pursuit of sustainable cutting fluid strategy for machining Ti-6Al-4V using life cycle analysis

The need for developing sustainable manufacturing processes which should have a good balance between economic viability and environmental protection is one of the key challenges against manufacturers. The conventional carbon-based cutting fluids used in machining processes are found to be unsustainable in terms of a higher impact on ecology and hence it is required to develop alternative sustainable cutting fluid strategies. However, the research that compares conventional, cryogenic and Minimum Quantity Lubrication (MQL) machining based on all pillars of sustainability i.e., machining performance, environmental impact and human health is still lacking. With this view, this novel study on Ti-6Al-4V machining compares conventional flood coolant with MQL and liquid carbon dioxide (LCO<inf>2</inf>) as a cryogenic coolant based on the machining performance and Life Cycle Assessment (LCA) analysis. Though lower impacts on the environment are observed for MQL machining, it is not sustainable as it has been observed 75% reduced tool life with a higher cutting force and surface roughness in comparison with flood and cryogenic machining. The flood machining is found to be non-sustainable as it has more than 50% of total impacts generated for most of the ReCiPe 2016 (H) midpoint categories. Thus, cryogenic machining is emerged as sustainable machining to have a good balance between machining performance and impacts on the environment for turning Ti-6Al-4V.