The Pareto principle and a hazard model as tools for appropriate scheduled maintenance in a manufacturing firm

This study relates to a manufacturing firm that produces sanitary towels in Nigeria. The firm was confronted with operational challenge of high production downtime occasioned by frequent breakdown of the subsystems of the production system. This situation thus threatened its survival despite monthly scheduled maintenance. The study obtained machine breakdown records from the production unit and estimated the percentage downtime of the subsystems in hierarchical order. Pareto analysis was used to determine that 6 out of 11 subsystems were responsible for about 80% of the downtime. The hazard rates of these subsystems were determined and failure distributions obtained. A better preventive maintenance plan based on these vital subsystems was proposed. The study was conducted using obtained machine breakdown records for 18 weeks and an estimated 2592 hours of machine time. The study concluded that general scheduled maintenance is not suitable for all the subsystems that make up the production system but that each, especially the critical ones, should be maintained separately at specific times as revealed by the hazard model.