Performance analysis of cryogenically treated plus tempered carbide inserts in turning of Inconel 718 using cryogenic minimum quantity lubrication cooling technique

The present study deals with performance investigation of cryogenically treated plus tempered carbide inserts during machining of Inconel 718. A novel cooling approach of combined minimum quantity lubrication with cryogenic coolant, cryogenic minimum quantity lubrication is examined to improve the machinability of Inconel 718 and compared with dry, wet, minimum quantity lubrication, and cryogenic cooling conditions. Tool wear, cutting forces, and chip morphology were analyzed to evaluate the effect of cooling under different conditions. The results revealed that minimum quantity lubrication and cryogenic conditions exhibited superior performance than wet and dry conditions. However, severe tool fracture and cutting forces were observed in cryogenic machining which is an outcome of hardened surface of nickel alloy due to cryogenic fluid. Cryogenic minimum quantity lubrication was understood to be the best machining condition generating least cutting force and tool wear. Furthermore, examining chip morphology under scanning electron microscopy revealed that cryogenic minimum quantity lubrication performed stable machining.