Application of Environmentally-friendly Cooling/Lubrication Strategies for Turning Magnesium/SiC MMCs

The material having high strength to weight ratio is constantly in high demand for automotive industries to increase fuel efficiency. With this view, AZ91/5SiC (an Mg-based Particulate Metal Matrix Composites (PMMCs)) is fabricated using an in-house developed stir casting setup and characterized through Field Emission Scanning Electron Microscopy (FESEM) with Energy-Dispersive X-ray Spectroscopy (EDS) analysis. However, the machinability of PMMCs is found to be lower due to the existence of harder ceramic constituents and appropriate cutting fluid strategies are required to follow to combat this situation. But limited studies are available identifying the impact of recently developed sustainable cooling and lubrication techniques on machining performance when PMMCs is turned. To fill this bridge, customized setups of minimum quantity lubrication (MQL), cryogenic and CryoMQL machining with LN2 have been developed to provide eco-friendly cutting fluid approaches to turn AZ91/5SiC. The cutting force, energy consumption, surface roughness (Ra) and chip breakability index (Cin) have been analyzed for MQL, cryogenic and CryoMQL techniques with variation in process parameters. By considering the average value of all turning tests, 64.65% and 40.39%; and 11.49% and 7.13% higher value of cutting force and energy consumption is found correspondingly for cryogenic and CryoMQL machining respectively as compared to MQL technique respectively. Overall, 25.59% and 18.35% lower values of Ra have been observed for CryoMQL technique as compared with MQL and cryogenic machining respectively. The powder type chips with comparable higher values of Cin have been found in all three cooling and lubrication techniques.