Tool Reliability Modeling Based on Gamma Process in Multiple Working Conditions

Tool reliability is the key factor to ensure the machining quality of CNC machines. Considering the variety of machining conditions in NC machine tool machining process, a Gamma-based tool reliability model considering various cutting conditions is proposed in this paper. Based on the reliability model of Gamma process, Taylor tool life equation is applied to change the form of shape parameter of Gamma process, and the shape parameter is modified to be related to spindle speed, feed speed and cutting depth. On the basis of maximum likelihood estimation, the complexity of the model is simplified, and the parameters of the model are obtained by genetic algorithm. According to the data about tool wear and machining parameters obtained by orthogonal test, the feasibility of the method is verified. Experiments show that the tool reliability model based on multiple working conditions can well fit the tool reliability under different machining conditions.