Modelling maintenance practice of production plant using the delay-time concept

In this paper, we present a study carried out for a copper products manufacturing company, developing and applying the delay-time modelling technique to model and thus optimize preventive maintenance (PM) of the plant. A key machine in the plant is used to illustrate the modelling process and management reaction. The parameter values of the process by which faults arise and of the delay-time distribution are estimated from maintenance record data of failures and faults found at PM, using the method of maximum likelihood. A test of the model fit to data is carried out. Based upon the estimated model parameters and the failure delay time, an inspection model is proposed to describe the relationship between the total downtime and the PM interval.