In order to assess the operational reliability of the horizontal machining center (HMC), field failure data for 14 HMCs over one year are collected from an engine plant of a large automobile manufacturing company in China. In contrast with the usual approach, which just pools the data from all copies under the assumption that each copy is modeled by the same power law processes (PLP), a new model based on the generalized linear mixed model (GLMM) is proposed for analyzing the failure data from all copies of HMC. A basic idea of this method is to assume heterogeneity among all copies of HMC; it is also found that the underlying model for each individual copy is a PLP model with different shape parameters and scale parameters in the GLMM model. This method can make inferences about both the population and each individual copy. Meanwhile, the modified Anderson–Darling test is adapted to the goodness-of-fit test of the model. The results of the analysis suggest that this method is effective to analyze reliability of HMC. Copyright © 2010 John Wiley & Sons, Ltd.