Comprehensive investigation of the effect of cryogenic process on machining of Inconel 718 superalloys with uncoated end mills

Inconel 718 is extensively used in crucial fields such as aerospace, space researches, and space stations due to its superior features such as high mechanical strength even at very high temperatures, high oxidation resistance, and resistance to high temperatures. However, this material is categorized as a difficult-to-machine material owing to its high specific strength, high tool wear, and low thermal properties leading to poor machinability and poor surface integrity during machining. In order to overcome the challenges that arise during the machining of these materials, the cryogenic process, which has been very popular in recent years, have come to the fore due to the wear resistance and hardness it provides for the tool. In this statistical and experimental study, Inconel 718 was milled with cryogenically uncoated end mill (UCC) and uncoated end mill (UC) at different cutting parameters. Surface roughness, abrasive wear, cutting forces, cutting tool wear, vibration values, hardness and Build up Edge (BUE) formation obtained as a result of machining experiments were investigated. It was determined that the values of all experimental results obtained with UCCs are lower than those of UCs. Also, the second order equations (by response surface methodology (RSM)) showed very promising values of R² (above 90%) and thus reflected the appropriate relation of the independent and dependent variables; therefore, RSM approach can be successfully implemented for predicting experimental values in milling Inconel 718 with UCCs and UCs.