Advances in renewal decision making utilising the proportional hazards model with vibration covariates

Increased competitiveness in the production world necessitates improved maintenance strategies to increase availabilities and drive down cost. The maintenance engineer is thus faced with the need to make more intelligent preventive renewal decisions. Two of the main techniques to achieve this are Condition Monitoring (such as vibration monitoring and oil analysis) and Statistical Failure Analysis (typically using probabilistic techniques). The present paper discusses these techniques, their uses and weaknesses and then presents the Proportional Hazard Model as an solution to most of these weaknesses. It then goes on to compare the results of the different techniques in monetary terms, using a South African case study. This comparison shows clearly that the Proportional Hazards Model is superior to the present techniques and should be the preferred model for many actual maintenance situations.