Behaviour of ceramic cutting tools when machining superalloys
The nickel-base superalloys Waspaloy, INCO 901 and INCO , 718 have been machined with four different types of ceramic cutting tools. The cutting inserts were pure alumina (CC620), mixed alumina (CC650), composite ceramic (WG-300) and finally silicon nitride (Kyon 2000). Tests in the form of turning were carried out, in dry and wet conditions, in order to study the behaviour of the above mentioned cutting tools when machining superalloys. The cutting speeds employed for these tests were 90, 150, 215 and 300 m/min with feed rates of 0.125 and 0.18 mm/rev together with depths of cut of 1 and 2.5 mm. Machining in the presence of different atmospheres was also performed. In the majority of cases depth of cut notching (DOCN) proved to be the domineering factor controlling tool lives under different cutting conditions. However, flank wear, nose notch and surface roughness were the other tool failure modes. Attrition wear was predominant throughout the tests which was influenced by the cutting temperatures. The high temperatures also caused diffusion wear mechanisms to take effect.