Combination of high feed turning with cryogenic cooling on Haynes 263 and Inconel 718 superalloys

Abstract The machining of heat resistant superalloys (HRSA) is one of the most challenging tasks for machinists. Unfortunately, the turning of these difficult-to-cut materials is very common in the manufacturing of cases for gas turbines components due to their excellent mechanical properties. Traditionally, these operations are very time consuming. In order to avoid failure and part rejection, very conservative cutting parameters are selected; so, there is a great margin to optimize cutting conditions in aerospace applications. Besides, the minimization or avoidance of coolant is day-to-day a shared practice. All these factors make the turning of HRSA a very complex problem. Lately, high-feed turning technique has emerged as an alternative to traditional turning for a faster, more productive, manufacturing. It is based on moving the tool from the jaws towards the tailstock in reverse mode with a very low side cutting edge angle. It is a promising process but rather unknown. This paper presents an experimental investigation of the cutting forces and their prediction in high feed turning of Nickel-Chrome based superalloys. Besides, the effects of using oil emulsion and CO2 cryogenic coolant were also studied. Straight turning tests on different aerospace materials, Inconel 718 and Haynes 263, were compared against AISI 1055, using comparable cutting conditions. After the tests, surface roughness was also examined with both types coolants. The results indicated a good agreement between model predictions and experimental results for the three tested materials. It was also shown that while oil emulsion was the best option for Inconel 718, cryogenic cooling with CO2 can open the path towards a more efficient and cleaner turning in the case of Haynes 263.