Open-pit mines rank among the most demanding environments on Earth. At Colombia’s El Cerrejón coal mine, which faces periods of extreme heat and humidity, a Hitachi EX3600-6 Excavator has surpassed expectations, clocking more than 100,000 hours of operation—far exceeding its anticipated lifecycle. Achieving this milestone is rare, with less than 1% of machines reaching such limits, yet El Cerrejón accomplished it through a robust preventative maintenance strategy.
Assembled in December 2008, the EX3600-6 was selected for a life extension trial. The mine’s “annual shutdown” strategy was pivotal, focusing on thorough monitoring and evaluation of key structural components. This included critical areas like the bases of all beds, the main frame, the track frame, and the side frames. Components identified with a 20% margin remaining on their average life expectancy were scheduled for major shutdowns every 6,000 hours.
Aligned with this established maintenance strategy, a robust path of predictive techniques is also being implemented for the excavator. These techniques are scheduled at frequencies determined by Reliability-Centered Maintenance (RCM) methodologies and defined through data analysis, enabling the maintenance of a proactive scheme for timely detection and intervention.
The predictive techniques include structural inspection of all principal components, ultrasonic testing at critical points based on historical data from the front attachments, finite element analysis simulations, vibration tests on power transmission components, and the application of thermography techniques as per the inspection strategy.
To enhance this approach, new technologies are being integrated, such as the use of drones to observe the operational behavior of components. These drones generate data that help predict component failure by monitoring temperature trends in hydraulic systems.
Throughout its more than 100,000 hours of operation, the EX3600-6 maintained an impressive availability rate, averaging between 84.7% and 86.5%, excluding the months designated for major shutdowns. Additionally, over the last 36,000 hours of operation, the excavator has demonstrated a reliability metric of 63.3 hours of Mean Time Between Failures (MTBF), further highlighting the effectiveness of the maintenance strategies in place.
The most significant finding from this study is that ensuring the extension of the equipment’s useful life has relied heavily on the creation, monitoring, and execution of specific maintenance activities defined through RCM. These activities have been enriched by various maintenance methodologies, with Lean Manufacturing standing out, a methodology widely used by El Cerrejón. The application of these methodologies is encapsulated in the operation chart known as the “maintenance strategy,” which is periodically adjusted and improved based on the fleet’s or specific assets’ failure history.
Furthermore, a taxonomic analysis of the failure hierarchy has allowed for the clear identification of asset vulnerabilities. This process has enabled the establishment of targeted actions to ensure sustainability in performance during the equipment’s operation.
Over its lifecycle, the EX3600-6 required complete replacement only of its side frames, a testament to the effectiveness of El Cerrejón’s maintenance regimen. During the annual shutdowns, significant repairs were carried out in the excavator’s internal workshop, including routine reconstruction and car body repairs. Non-structural components were continuously monitored and replaced as needed, ensuring the machine operated at peak performance throughout its extended life.
