Machinery Lubrication

Machinery Lubrication November-December 2018

Machinery Lubrication magazine published by Noria Corporation

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Page 4 of 74

Contamination Control AS I SEE IT Jim Fitch | Noria Corporation Be Alert to Heat as Both a Contaminant and a Symptom Excessive heat is a severe contaminant. It wreaks havoc on oil (chemically and physically) and retards lubricant performance by increasing wear, corrosion and friction. Friction and wear cause more heat, which sends the machine into a cycle of despair. Heat must be controlled within the machine's operating limits. is varies considerably between machine types and applications. Lubricants have their own unique limits as well. Attempting to solve heat problems by simply adding a cooler or enlarging the cooler just masks the symptom and prolongs the solution. Abnormal heat is a telegraphed S.O.S. call that commands attention and remediation. Critical temperatures on most high-speed and high-value machines "When a bearing is running hot, the usual suspects are misalignment and impaired lubrication. Likewise, the fi rst and most pronounced symptom of misalignment and impaired lubrication is excessive heat." 2 | November - December 2018 | www . Figure 1. The No. 2 generator bearing experienced lubricant starvation due to grease cake-lock con- ditions within the housing. The slinger ring failed because of the cake backup, which led to impaired bearing lubrication and tripped the turbine. How was this observed by inspection? Grease was going into the bearing by an auto-luber. However, on the other side of the bearing, only oil was coming out and fi lling the drip pan. The thickener was logjammed in the bearing, and the oil was pressed through the porous cake (thickener) like a fi lter press. The bearing temperature rose from 65 degrees C to more than 100 degrees C when it tripped. Continued on page 4

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