<![CDATA[The six-unit Open Top Roller (OTR) system at the milling station of PT Perkebunan Nusantara IV Regional IV Unit Usaha Danau Kembar recorded 43 failure events and accumulated 519 machine-hours of downtime, yet its effectiveness and performance losses had not been comprehensively measured. The objective of this study was to measure the effectiveness of the OTR system using Overall Equipment Effectiveness (OEE), identify losses through the six big losses framework, establish priority causes, and develop maintenance improvement proposals. A quantitative descriptive method was employed by calculating machine-hour-based OEE, analyzing six big losses, identifying causes through fishbone diagrams, and establishing priorities using Failure Mode and Effects Analysis (FMEA), critical values, and cross-functional validation. The results showed an average OEE of 66.75%, comprising 96.52% availability, 69.18% performance efficiency, and a 100% quality rate for OTR outputs accepted for subsequent processing, while reduced speed losses constituted the largest measurable loss at 29.77%, with nine priority causes identified. These results indicate that high operating-time availability has not been accompanied by output achievement at the ideal capacity because process speed, machine-condition recording, maintenance activities, initial inspections, and workplace cleanliness have not been controlled consistently. The findings demonstrate that improvements to the OTR system should focus on controlling reduced speed losses and equipment failure losses through five proposed improvement instruments: an OTR component inspection and maintenance interval standard, an OTR operational readiness checksheet, an OTR machine and workplace cleaning checksheet, a standard operating procedure for raw material preparation and cleaning, and an OTR speed and stability monitoring checksheet.]]>
