Prognosis of the local tool wear in gear finish hobbing

Gear finish hobbing is a method for soft finishing of external cylindrical power transmission gears. The application of this process is required when the process chain of gear production is to be set up completely free of coolant. Since this finishing technology is relatively new, there is some practical experience, but no fundamental knowledge regarding economical process design. One challenge in process design is that unbalanced tool wear typically leads to geometrical deviations of the machined gear profile. The aim of the investigations described in this paper is to develop a wear model which is capable to predict the local tool wear of gear finish hobbing tools. This model is based on analogy cutting trials and geometrical analyses of the chip geometries in gear finish hobbing. The results of the model are validated by fly-cutting trials with different local loads on the tool. The validation shows that an optimization of the local tool wear development can be achieved by means of the prediction model. Therefore, an optimization of the technological process parameters can be carried out based on this model to reach an efficient process design.