Reliability-Based Preventive Maintenance Scheduling of a Multi-unit Injection Molding System: A Case Study

In industrial manufacturing, the paucity of an integrated approach for determining preventive maintenance intervals in multi-unit systems poses challenges. Achieving optimal system performance and reliability is crucial for productivity and profitability. This study proposes an integrative approach that optimizes preventive maintenance intervals for each mold unit within the multi-unit plastic injection molding system while considering reliability, availability, maintainability, and supportability (RAMS), an aspect previous studies have not considered. The objective is to enhance system reliability, reduce downtime, and improve overall performance. For the first time, the study concurrently explores reliability, availability, maintainability, and supportability analysis for an injection molding plant. The results of this investigation show that the RAMS analysis can be used to determine the prevention maintenance schedule of each subunit to achieve the desired plant reliability level. The study reveals that an 80% reliability level yields optimal preventive maintenance intervals. The mean availability of the molding unit drops beyond the 80% anticipated reliability level due to excessive maintenance, but its reliability improves as the preventive maintenance interval is reduced. Using simulation, we further examine how preventive strategies affect the injection molding unit's improvement in availability, reliability, and reduction in downtime. The insights gained from this study may assist the maintenance manager in maintenance planning and scheduling. Future research utilizing a holistic approach might reveal novel perspectives that can enhance decision-making processes for injection molding systems management.