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
.
machinerylubrication.com
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
