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© 2016 - H-T-L perma USA

LP

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www.permausa.com

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5

ROLLER

BEARING

FAILURES

Unsuitable

lubricant

Insufficient

lubricant amount

Solid

contamination

Other

failure

causes

Liquid

contamination

Aged

lubricant

Bearing damage

Over-lubrication

Insufficient lubrication

Source:

Calculation leading bearing manufacturers: Material cost and time,

maintenance runs / roller bearing industry

To maintain competitiveness, mining and heavy industry

operations such as steel mills must maximize production output

while minimizing long-term operating costs. A key component to

achieve this is the implementation of preventative maintenance

strategies which extend equipment service life and minimize the

downtime required for maintenance, repair and overhaul. Success

in this area reduces the total cost of production assets and

ultimately improves business performance.

Cost and downtime due to premature wear is significant. For

grease lubricated bearings, well considered lubrication strategies

have a dramatic effect on extending bearing service life and

therefore reducing costs and improving equipment reliability.

The chart provides estimates of the causes of premature bearing

failures. Major causes are poor lubrication practices and conta-

mination.

In recognition of this, industry leading businesses invest in

automatic lubrication systems for the purpose of bearing

relubrication and contaminant exclusion because they deliver

superior reliability results compared to manual lubrication.

Benefits of short relubrication intervals

Introduction

Bearing relubrication addresses the need to maintain sufficient

fresh grease around the working components of bearings as

they rotate. Insufficient or infrequent relubrication leads to

deterioration of lubrication conditions, lubricant starvation, and

premature wear. Meanwhile, for high speed bearings, the rapid

supply of excessive amounts of grease can cause over-lubrication

which leads to degradation of grease condition and threatens

the service life of bearings.

The longest bearing service life is achieved when grease is added

in small amounts at short intervals. When implemented correctly,

this regime of grease delivery maintains a steady state of

lubrication protection where over-lubrication and lubricant

starvation do not occur.

Factors which reduce the service life of grease include high speeds,

elevated operating temperatures, vibration and high loads. When

operating conditions such as these prevail, the benefits of delivering

small amounts of grease at short time intervals are at their greatest.

The diagram to the right demonstrates the differences between

re-lubrication methods which deliver small amounts of grease at

short intervals and those which deliver large amounts at extended

intervals.

Too much grease

Potential for elevated operating

temperature and rapid degradation

of grease for high speed bearings

Less efficient use of fresh grease

Potential to damage contact type seals

Too little grease

Starvation causing premature wear

Under-lubrication leads to accelerated

degradation of remaining grease

Increased potential for contamination

entry due to lack of lubricant purge