Distribution of Time Between Failures of Numerical Control System Based on Censored Data

The calculation of mean time between failures (MTBF) is of significance in reliability engineering. The precondition before calculation of MTBF is to make sure what failure model the numerical control (NC) system follows. For different distributions, the corresponding calculation methods of MTBF are always different. Undertaken a 2 year period of timing censored test with replacement of NC lathe, authors apply a type I censored likelihood function to make the distribution fitting of time between failures of NC system. The tests of goodness-of-fit applying Hollander's method demonstrate that the time between failures of NC system follows the Weibull distribution. The conclusion not only deeply analyzes the NC system failure law, but also establishes the basis of calculation for the mean time between failures of NC system based on censored data with replacement.