Maintenance strategy enhancement through FMEA and FTA: Ahlstrom case study.

A well-structured maintenance function is essential to remain competitive in the current industrial landscape, where maintenance has become a value-generating activity. The objective of this thesis investigates methodologies and techniques for the selection of maintenance strategies, alongside a comprehensive review of current condition-monitoring technologies, with the aim of proposing a structured approach for maintenance enhancement at the Mathi Alstrom paper mill. In the first part, a literature review is conducted to examine maintenance approaches, strategies, risk assessment tools, including Failure Tree Analysis (FTA) and Failure Mode and Effect Analysis (FMEA), and the key concepts of the Industry 4.0 paradigm. The current maintenance practices ("AS IS" situation) at the plant are analyzed, highlighting the different strategies used depending on the type of equipment and the condition assessment techniques currently in place. The proposed approach is applied to Paper Machine 8, identified as a critical asset. Through the application of FMEA and FTA, the most critical components are identified and ranked, with the gearboxes of the drives, and the bearings and gears of the dryer cylinders emerging as priority elements. Based on these findings, a combination of thermographic and visual inspections is suggested, along with a review of inspection frequencies. Additionally, the implementation of an online vibrational monitoring system is proposed to enable continuous condition monitoring. The benefits of the proposed strategy are analyzed theoretically, with an evaluation of historical failure data from 2020 to 2024. Improvements in Mean Time Between Failures (MTBF), Mean Time To Repair (MTTR), and losstime are calculated. The proposed solutions show potential to reduce losstime by approximately 10% in the case of gearboxes and over 50% in some years in the case of bearings of the drier cylinders. Finally, the technical and economic feasibility of the online monitoring system is assessed, identifying safety improvement as one of its key advantages. The thesis concludes by discussing the benefits, limitations, and possible future developments, including suggestions that emerged during the research.