Influence of Tool Tip Temperature on Crater Wear of Ceramic Inserts During Turning Process of Inconel-718 at Varying Hardness

The present study investigates the effect of Tool Tip Temperature on crater wear of cutting inserts of ceramics in the machining of Inconel 718 with varying hardness ranges from 26 HRC to 45 HRC respectively. The effect of cutting speed on the tool-tip- temperature and crater wear has also been investigated. A series of tests were conducted to measure the tool-tip temperature during the turning process, under controllable process parameters. Aluminum - oxide ceramic (620), mixed - oxide ceramic (6050) and silicon- nitride ceramic (6190) Sandvick triangular cutting inserts were used under dry conditions of machining. It was observed, that the temperature of cutting rises monotonically due to an increase in cutting speed. Further, temperature built up on the surface near to the tooltip leads to crater wear. The significant difference was observed in crater wear for (i) varied hardness of work-piece (ii) different cutting speed and (iii) several ceramic turning inserts with fixed machining time. The al-oxide insert has shown better cutting performance low crater wear, in comparison with silicon nitride, and mixed oxide turning inserts irrespective of the hardness of work piece and also cutting speed. Further, with the increase of work piece hardness from 26 HRC to 45 HRC, i.e. 58 % of increase of hardness has a strong influence on higher temperature rise 71% at the tooltip. Further, 26 HRC possess gave better crater wear resistance.