CUTTING TEMPERATURE OF CERAMIC TOOLS IN HIGH-SPEED MACHINING OF DIFFICULT-TO-CUT MATERIALS

This paper deals with an experimental and analytical investigation int o the different factors which influence the temperature distribution o n Al2O3-TiC ceramic tool rake face during machining of difficult-to-cu t materials, such as case hardened AISI 1552 steel (60-65 Rc) and nick el-based superalloys (e.g. Inconel 718). The temperature distribution was predicted first using the finite element analysis. Temperature mea surements on the tool rake face using a thermocouple based technique w ere performed and the results were verified using the finite element a nalysis. Experiments were then performed to study the effect of cuttin g parameters, different tool geometries, tool conditions, and workpiec e materials on the cutting edge temperatures. Results presented in thi s paper indicate that for turning case hardened steel, increasing the cutting speed, feed, and depth of cut will increase the cutting edge t emperature. On the other hand, increasing the tool nose radius, and an gle of approach reduces the cutting edge temperature, while increasing the width of the tool chamfer will slightly increase the cutting ege temperature. As for the negative rake angle, it was found that there i s an optimum value of rake angle where the cutting edge temperature wa s minimum. For the Inconel 718 material, it was found that the cutting edge temperature reached a minimum at a speed of 510 m/min, and feed of 1.25 mm/rev. However, the effect of the depth of cut and tool nose radius was almost the same as that determined in the turning of case h ardened steel. It was also observed in turning Inconel 718 with cerami c tools that, cutting forces and different types of tool wear were red uced with increasing the feed.