Experimental investigation on high-efficiency grinding of Inconel 718 with heat pipe grinding wheel

Grinding heat is a significant problem for grinding difficult-to-machine materials such as nickel-based superalloys, which restricts their applications. A majority of existing cooling methods ensure cooling by simply increasing the volume of coolant. However, lubricants often lose efficacy due to film boiling and have adverse health and environment effects. To dissipate grinding heat in the contact zone and guarantee workpiece surface quality, a novel cooling method that dissipates grinding heat assisted by forming rotating heat pipe inside the grinding wheel (HPGW) is proposed. Tests were performed to determine its heat transfer capacity in high-efficiency grinding of Inconel 718 alloy. The results show that grinding with HPGW leads to lower grinding temperatures and lower thermal damages to the workpiece when compared to grinding with non-HPGW. Better heat transfer capacity of HPGW is explained by heat transfer resistance analysis for both grinding wheels. The analysis proves that the value of HPGW is one order of magnitude lower than non-HPGW. Furthermore, in-depth studies of the ground surface showed no changes in microstructure or microhardness for the workpiece when using HPGW, whereas different degrees of burn were seen as indicated by different temper colors and corresponding changes in microstructure and microhardness.