Support
An induction bearing heater.
The bearing is placed over a bar of laminations, which is then
positioned correctly over other laminations of the induction heater
unit. The unit will have electronic control of induced temperature.
A contact-type electronic thermometer may be used to
read the temperature of the bearing inner ring (or outer ring, in
the case of an interference fit to the housing). Disconnect the
inductive heating field before taking a reading.
When the bearing is up to the fitting temperature, lift it, using
clean, heat-resistant gloves or a clean, lint-free cloth to hold
the bearing. Slide the bearing into place on the shaft. Hold it in
position until it cools sufficiently to take a grip on the shaft.
Note: Always use a thermometer; never take a guess at the
temperature. Permanent damage will be caused to the bearing if
it is overheated to beyond the 125°C limit.
operating range. Use a lithium grease as standard, unless you are
re-lubricating bearings you know to be lubricated with another
grease. In that case, re-lubricate with the grease of the type
already in the bearing.
Never leave an opened can of grease lying about. This is
certain to collect harmful dirt. If you are filling a grease gun,
do so only from a can of grease you know to be completely
clean. Do this task in clean surroundings. However, when you
are filling a bearing with grease, do so from a tube. Provided
you first clean the tube end, you are sure in this way of having
contaminant-free grease.
If you are handling grease from a drum, do not use wooden
paddles or spatulas to help with the job. They are sure to carry
dirt. Only use metal items, which have been completely
wiped clean.
Only just before you fit the shaft and bearing into the housing,
completely pack the bearing with grease. Fit the greased bearing
on its shaft into the housing and add grease to the housing until
the bearing is between 30% and 50% filled with grease.
Note that petroleum products can cause skin allergies. Use
disposable gloves or other protection to keep your hands from
becoming covered with grease.
Do not mix greases. When cross-lubrication takes place, the
mixed grease is softer than either of the original greases.
If in doubt when re-lubricating, open the bearing housing
and remove as much of the original grease as possible.
Then re-lubricate with lithium grease or the manufacturer’s
recommend grease.
Moses, I hope this assists you with the basic procedures for
bearings and that this helps you to minimise repeat failures. RACA
LUBRICATION
If bearings are fitted to applications such as many pumps that
run in an oil bath, then naturally this lubrication method will stay
in operation.
Grease lubrication is by far the most common lubrication
system for rolling element bearings. Bearing greases employ
thickeners to ensure good adhesion to the important surfaces.
You could find bearing grease in use with calcium, sodium, or
lithium thickener. Lithium has all the advantages of the other two
without their disadvantages, such as limitations of temperature
64
RACA Journal I January 2019
Thank you for all your questions. Send your problems (and
sometimes your creative solutions) to acra@netactive.co.za
with “Solutions Page” in the subject line.
You may include pictures.
REFERENCES
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ACRA
FAG Bearings
SKF Bearings.
www.hvacronline.co.za