Reliability assessment of multiple NC machine tools based on three-parameter Weibull Process model

In order to accurately evaluate the reliability of multiple NC machine tools, a method on reliability assessment of NC machine tools based on three-parameter Weibull Process model is proposed. The calculating formula for the optimal maximum likelihood point estimation of model parameters and reliability index are all derived, a mathematical model for solving the model parameters with an optimal method is given, and the model parameters are solved by using the immune clonai selection algorithm. An example of real failure data from multiple NC machine tools is taken to prove the proposed method, the result of goodness-of-fit show that the fitting accuracy of the model is high and it is suitable to describe the failure process of NC machine tools.