CLEAN LIVING: AVOIDING
LUBRICANT CONTAMINATION
earing grease plays a
huge role in making food
processing machinery run
more efficiently, but can
be a contamination hazard
– which food processors must work hard
to avoid as Phil Burge, Marketing and
Communications Manager at SKF explains.
B
In common with other manufacturing
sectors, the food processing industry relies
on high-speed, efficient machinery to turn
raw materials into finished products. This
requires the machinery to be properly
serviced and lubricated. While this boosts
efficiency, it can also have a potential
downside: contamination.
The rest of manufacturing is largely
immune from this problem. If some stray
lubricant drips onto a die cast product,
for instance, it can simply be wiped off
before being packaged and shipped. If the
same happens with a loaf of bread, or a
ready meal, the whole batch may have to
be scrapped – or worse, recalled at a later
date.
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PECM Issue 32
Of course, machine components like
bearings must be lubricated if they are to
operate at maximum efficiency. So, it is
vital to find away around the problem of
contamination.
In general, there are three main
approaches: use food-grade lubricant; seal
components tightly, to make lubricant
leakage almost impossible; or replace
grease with some form of ‘dry’ lubricant.
Food-grade lubricants are widely used,
and are certified for food production
environments. However, intensive cleaning
processes – which are vital for hygiene –
can cause lubricant to leak out, or water to
force its way in. Even if a lubricant is food
grade, nobody wants it leaking into their
product.
G rease resistance
One way to remedy this is to seal
the bearing very tightly, to create an
impassable barrier.
One of the most difficult processes for
bearings to handle is washdown: high
pressure water jets flush away germs,
but can also penetrate bearing seals to
cause leakage. Some food processes,
such as poultry production, can require
washdowns every shift. This can mean
water, detergents and other contaminants
being forced into seals, leading to early
bearing failure.
This problem was leading one poultry
processer to replace hundreds of nickel-
plated cast iron bearings every few
months. To overcome it, the company
fitted SKF Food-Line Y-bearings – with
composite housings, stainless steel
bearing inserts and a special multi-lip seal
(called a 2RF seal) that prevented grease
displacement and water ingress.
The quality of the seal paid dividends:
after the change, bearing service life was
quadrupled, while the company also made
huge savings through the reduced need
for re-lubrication.