Oil sampling and analysis as a condition monitoring program has been around for many years as part of operating and maintaining heavy mining equipment. The program and photos cited in this case study were from an open-cut coal mine that kicked off their oil sampling program in the 70’s. However, after some time this site reflected on the experiences of theirs and other mines. They began to realise they did not initially achieve the benefits of improved equipment reliability that were desired from the program. It took 10 years before they got it right and it required them to ask themselves, are we getting value from this program?
When asked about their oil sampling program, this is the feedback from the mine for how the program ran in the first 10 years.
When the site realised the program wasn’t effective they implemented an improvement program. The program included the following.
The supervisors were engaged first so they understood what the program was meant to do and how it was going to happen. As part of this program, supervisors were sent to the lab to understand the oil analysing procedures and factors that can influence interpretations.
Tradespeople were formally trained to enable them to understand the results. A simple “Understanding of Oil Analysis” awareness training was started. It was developed and delivered in-house with the only cost being the trades person’s time.
One key element of the training was the concept of contaminated oil hiding impending failures, which was explained as part of the training. This is where the oil in the equipment is not clean enough to allow the early increases in wear metal in the sample to be visible during the oil analysis process. The excess contamination, that has been left over from historical wear, creates a high level of “background noise” in the measurement of the wear metals. This elevates the “normal” wear metal levels above the levels you would see in an early onset of a failure so the early onset of failure is hidden until the failure has progressed closer to its ultimate failure point. This concept is represented in the graphic below and can apply to any of the wear elements used to identify failures.
The graphic shows that good signal detection range (early failure detection) is achieved when the oil contamination is low at ISO -/13/10. If the oil contamination is high at say ISO -/19/16 then the time to failure from detection will be much less.
Led by the supervisors the tradespersons took ownership of the process and its outcomes.
To aid the interpretation of the oil analysis, the lab was asked to provide trends of the last five sample interpretations on one report which gave more insight to the analysis. It also highlighted where samples were missing or not taken correctly.
These are the benefits stated by the mine now that the program is working for them.
By Gerard Wood