By Shesby Chabaya, HOD, WearCheck Zimbabwe Ops.
The road construction industry is naturally a high-dust environment that requires regular monitoring of all machine components to identify possible threats or risks before they negatively affect equipment.
Recently, the WearCheck team tested an oil sample from a client in the road construction industry. Below, are the details of the findings and lessons learnt with regards to the effects of dust contamination on machine health, as well as how these lessons can be utilised to re-model the oil sampling regime for greater success.
Laboratory findings at the 2,000 hour service were as follows: Iron 639ppm, Chromium 21ppm, Nickel 18ppm, Copper 147ppm, Lead 180ppm, Silicon 156ppm and particle quantifier reaching 12 995MgFe/L. The microscopic particle examination revealed the image below:
|An interpretation of these findings pointed to evidence of a severe wear situation and a critical silicon (dust) level in the oil. The laboratory assigned critical severity status to the engine, and recommended immediate checking of the air intake system, among other checks.|
An interpretation of these findings pointed to evidence of a severe wear situation and a critical silicon (dust) level in the oil. The laboratory assigned critical severity status to the engine, and recommended immediate checking of the air intake system, among other checks.
Customer feedback revealed that the engine failed shortly after the service was done. The root cause of dust ingress was discovered to be a torn air induction hose. The tear was not easily visible with the naked eye, as it was located on the inner side of the air induction hose close to the engine block.
Evaluation - the tear on the air induction hose resulted in cement dust bypassing the air filtration system and being sucked directly into the engine, thus accelerating the rate of component wear. This scenario is that of correlation between a cause and effect as illustrated in the diagram below:
The road construction industry involves the application of cement during road construction, and any opening on the engine components will result in severe contamination, which poses a huge risk to component failure.
The torn air induction hose is the root cause of dust ingress, and the effect is severe wear (dust being the catalyst) and consequent engine failure. When an air induction pipe cracks after the air filter, dust enters the air intake manifold and finds its way into the engine. The dust mixes with lubricating oil and is carried through the engine via the lubrication system, acting like a “grinding paste” and wearing out components. The engine may fail to last longer than 300hrs depending on the intensity of dust ingress.
Unfortunately, this engine had not been sampled since the machine was commissioned. Only a single sample came through at 2,000hrs. Had the machine been sampled every 250hrs, the problem could possibly have been picked up earlier and rectified, avoiding a catastrophic failure.
A more regular and systematic oil sampling regime following set oil sampling intervals results in huge cost savings and increased equipment reliability. With a properly set up condition monitoring programme in place, specific parts can be ordered, and maintenance can be planned, thus avoiding interruption to business.