When converting from one grease to another, it may be helpful to determine how much soap residue is in the bearing housings and estimate how much flushing will be necessary to eliminate the old material. If the amount of old material is low and the residue is soft and pliable, then you may be able to simply increase the relube frequency, perhaps doubling the cycle for a while to flush out the old grease.

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Book Bits: Rate-of-Change Based Alarms

From the book "Oil Analysis Basics"

Rate-of-change alarms are typically set to measure properties that are being progressively introduced into the oil, such as wear debris. The add rate (change) can be calculated per unit of time, hours, cycles, etc. For example, a 100 ppm increase in iron over a period of 100 operating hours could be stated as one ppm per hour of operation. When the parameter is plotted against time, the rate-of-change (add rate) equals the current slope of the curve.

Unlike level limits, rate-of-change limits ignore the absolute value of the data parameter, emphasizing instead the speed at which the level is changing. Rate-of-change limits are effectively applied to particle counting (unfiltered systems), elemental wear metals, ferrous density, acid number (AN) and RPVOT. It can also be effectively applied to monitor abnormal degradation of additives with elemental and FTIR spectroscopy.

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"We alternate between having mechanics perform machine lubrication in their respective work areas versus having designated lubrication technicians assigned to do just this work. What is the current trend in industry? Has either approach proven to be better at supporting machine reliability?"

The first question to answer is this: What is the purpose for the plant lubrication program? Do you schedule lubrication rounds because they are in the computer, or do you schedule the rounds to drive reliability?

Many lubrication programs exist because management understands that lubrication is a necessary part of maintenance. Within this strategy it is likely that supervisors would argue to maintain departmental control of available labor (resources) – which inevitably leads to mechanics performing lubrication activities when nothing else requires their attention. Unfortunately this also leads to a poorly performing lubrication program.

If the lubrication program is created as a critical path to drive reliability, and management has recognized that there are special tasks to be done, and which require specialized knowledge, then supervisors would argue to maintain dedicated technicians to perform the tasks. Additionally, when personnel are designated to a specific task, there is ownership for the results. This can be a strong and positive motivational force.

Mike Johnson, Noria Corporation

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