Influence of Kinds of Cemented Carbide Hob Materials in Hobbing with MQL System

Abstract

This paper investigates the influence of kinds of cemented carbide hob materials coated with fully TiN and (Ti, Al)N coatings, in hobbing with minimal quantity lubrication (MQL) system compared with dry cutting in cutting performance, in terms of flank wear (tool life), crater wear and finished surface roughness. Experiments were carried out by simulating hobbing by fly tool cutting on a milling machine. The results obtained are summarized as follows. (1) When changing the kinds of hob materials, P10, P20 and P30, as a substrate, the P30 hob material showed a longest tool life, even if the kinds of coating films were changed. The tool life obtained with the Fully (Ti, Al)N-coated tools is longer than that obtained with TiN-coated tools. The flank wear reduction effect by MQL system, which prolongs the tool life compared with the dry cutting, was recognized. (2) Although the reduction effect was recognized in the crater wear, the thermal cracks occur on the rake face of both fully TiN-and (Ti, Al)N-coated P30 tools. (3) The MQL system decreases the surface roughness with all of the cemented carbide hob materials and the coating films tested. (4) From the viewpoints of the tool life, the crater wear and the surface roughness, the use of MQL system for the fully (Ti, Al)N-coated P30 tool is effective.