Simulation of the tribological behaviour of tools for cutting ductile materials

Abstract

Cutting tests are very costly when expensive materials are to be cut. Therefore model tests are required which allow a preselection of materials or coatings to increase the lifetime of cutting tools. The wear of indexible inserts for milling a soft magnetic highly ductile nickel - iron alloy is simulated by means of a modified pin-on-disc system. For the simulation a detailed systems analysis of the tribological processes during cutting and model wear testing is necessary. Cutting tests revealed that flank wear is the wear-determining process. Therefore the flank of an original indexible insert was pressed against the flat surface of a rotating disc which was made of the nickel - iron alloy. By reversing the direction of rotation in comparison to the cutting process only sliding took place. The flank wear - distance curves of the model wear tests resembled the wear curves of the cutting tests. In both tests nickel - iron was transferred to the flank of the indexible inserts. By physical vapour deposition (PVD) of TiN, friction, adhesive transfer and wear were considerably reduced. These tests give valid information on the tribological behaviour of uncoated and coated indexible inserts for milling highly ductile nickel - iron alloys, but real lifetimes of the tools can only be determined by milling tests.