Lube-Tips

Don't let your focus with lubrication issues cause you to overlook other causes. We had a fan bearing that ran well, but required grease every three or four days. We knew this because of ultrasonic monitoring. After about three months running time the addition of grease started to have no effect and bearing vibration began to increase.

We had to call the vendor in on this one and we found that the roller ball bearing was under loaded. The belt tension that the manufacturer recommended was not sufficient to load the bearing adequately. Bearing failure would have occurred if we had not performed ultrasonic and vibration monitoring. The greasing protected the bearing over the time it took us to figure out the root cause of the problem. (Submitted by Bill Jacobyansky, Maintenance Manager, Guardian Industries. Thanks Bill!)

From "Total Contamination Control 98"

Estimation of contamination ingression rates and the rate of wear debris generation are required to determine the contamination level in the system. Ingression rate is the most critical parameter in contamination control. However, because the ingression rate is difficult to test using off-line methods the estimation of ingression rate has mainly been based on guessing. Ingression rate is a dynamic parameter which exists only in a running system and it is difficult to monitor. Environment contributes greatly to system contamination. Contamination enters the system via the fluid reservoir (air breathers and access covers), and any sealing pairs (cylinders seals, pump and motor seals). It is estimated that about 50-60 percent of contaminants enter via the cylinder seals and it can be expected that the amount of ingression will increase with seal wear.

More information about the book "Total Contamination Control 98"

Lube-Trivia: How Does Viscosity Change?

Test your knowledge and prepare for ICML lubrication and oil analysis certification.

Q & A: Contaminated Hydraulics Puzzling

"Sometimes our oil analysis reports show high particle counts on a hydraulic system - as high as ISO 21/18. If wear metals and silicon are low, less than 4 ppm, what are these particles?"

To fully understand the composition of the particles, a spectrographic analysis and a metallurgy assessment of your system components will tell you what the particles are and where they are coming from. At 4 ppm, the amount of wear metals is insignificant.

Retest the system on a proper frequency and trend the rate of change. Significant change in the overall amount of wear metals is cause for concern. If the value of wear metals hovers around the same ppm over each test, then you are probably looking at a product of normal operation. Keep in mind that spectroanalysis can pick up particles only 7 microns and smaller at absolute best. The accuracy can also be off by significant values on some metals.

I suggest you approach your concern with ferrous density and a patch test after a particle count. Set your target cleanliness for particle count. If the tested value is greater than the target value, proceed to a ferrous density test. Set a target for this value as well, maybe 15 percent ferrous. If the value of the ferrous density exceeds 15%, proceed to an analytical ferrography. If the value of the ferrous density is less than 15 percent, proceed to a patch test (filtergram). Keep an eye out for high rate of change in any of the tested values and you will be able catch problems before they occur.

It is also a good idea to assess the condition and effectiveness of your breathers and filters to make sure you are keeping contamination out and removing it effectively when it gets in.

Jason Kopschinsky, Technical Consultant, Noria Corporation

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