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Overview

Lube Procedure

Lubrication: the single most important factor in machine performance, Ron Jonkers, Jonker Machine Condition Engineers

Bearings lubricated on a time based schedule are more prone to premature failure than bearings that follow a condition based schedule.  In a time-based scenario lubricant is rarely added at the exact time it is needed; allowing the bearing to run “dry” for extended time frames.  When the bearing is finally greased the amount of lubrication can be too little or too much.  In either case the implications for bearing life are negative.

A condition based schedule involves frequently monitoring the bearing to establish normal baseline friction levels.  As the job of lubricant is to reduce friction, it stands to reason that increased baseline readings would indicate a need for re-lubrication.  Monitoring friction levels while lubricating serves as a guide to prevent over lubrication.

A simple and common approach to monitoring and setting baseline friction levels is with an ultrasonic data collector.  These portable instruments use high frequency piezoelectric sensors to detect, measure, and trend ultrasonic signals from rotating equipment.  Friction from the bearing excites the sensor which in turn produces a micro volt charge which is accurately measured and referenced to a decibel log scale.  This data is displayed onscreen and stored to the internal data collector.  It can then be transferred to PC where for further analysis.  As a rule any bearing with a measured ultrasound value 8-10 dBµV over its baseline should be greased using the acoustic lube method.

Using an ultrasonic data collector to predict greasing schedules is part of the task.  Using the same instrument during the greasing phase helps the lubricator add the correct amount of grease, without over greasing the bearing and causing more problems.  This is normally performed by coupling the ultrasonic sensor to a standard grease gun via an acoustic lube adaptor (fig. 1).  These adaptors are made to fit a variety of fittings including zerk and button head styles.