Fatigue fracture investigation of cemented carbide tools in gear hobbing, Part II: The effect of cutting parameters on the level of tool stresses - a quantitative parametric analysis

Gear Hobbing is a complex gear manufacturing method, possessing great industrial significance. The convoluted geometry of the cutting tools brings on modeling problems and is the main reason for the almost exclusive application of HSS as cutting material. However, despite its complicated kinematics, gear hobbing is sufficiently described by well-established software tools, which were presented in the first part of the present paper. Experimental investigations exhibited the cutting performance of cemented carbide cutting teeth, which were expected to be potential alternatives for massive hob production. In these cutting experiments, hardmetal tools exhibited in several cases early and unexpected brittle failures, which were interpreted by the FRSFEM model in the first part of the paper. This analysis indicated that the occurring dynamic stresses are the reason for the observed fatigue failures on the cemented carbide tools. The occurring stresses are highly dependent on the selection of cutting parameters and on the tool geometry. Therefore, the proper selection of the cutting data may prevent the early tool failures, as the dominant parameters for tool wear, allowing it to be worn out by the conventional abrasive mechanisms. Thus, the doubtless dominance of cemented carbide over the HSS tools, may be rendered. The present work illustrates a parametric analysis, which describes quantitatively the effect of various cutting and technological parameters on the stress level occurring in gear hobbing, with cemented carbide cutting teeth. Hereby, the optimization of the tool life is enabled, allowing the maximum exploitation of modern gear hobbing machine tools. Optimized gear hobbing with cemented carbide tools may be used, in order to introduce higher cutting speeds in massive gear production.