New Danfoss VLT® Decentral Drive E cient, reliable and powerful

Extend your chain
lives at no extra cost
Simply by looking for signs of early wear and eliminating the cause,
engineers can prolong the lives of conveyor and transmission chain without
incurring any extra costs, says Renold Chain’s marketing communications
manager, David Turner, in the first article in a series.
BEARINGS, BELTS & CHIAINS
Standard roller chain is
designed to last at least
15,000 hours. Certain
unavoidable factors may shorten a
chain’s life, but if chain is routinely
needing to be replaced before this,
then it is worth checking to see if
anything can be done to extend its
working life. Often it can.
If it were possible to get just
10% more life out of every strand
of chain on every production line
and machine in a factory, the
savings would be enormous when
extrapolated over a year – not just
in terms of reduced chain
replacement costs, but also
through reduced downtime.
Every year, our engineers come
across dozens of cases where chain
has worn prematurely due to
relatively minor problems that could
have been put right quite easily.
When you consider that some
production lines are running
hundreds – possibly thousands –
of metres of chain, it’s not difficult
to work out that if each strand
could be made to last longer, then
real savings could be made across
the whole factory. Even small
operations can benefit from
extended chain lives, especially
when all that may be needed is a
little time to investigate operating
conditions and to consider
maintenance routines.
To find out where the tweaks
and adjustments might be needed,
first undertake a thorough visual
inspection of the chain while it is
not running. Just as a forensic
pathologist can look at a dead
body and determine the cause of
death, if a chain is suffering from
premature wear, there will be visual
signs that can be spotted easily.
Although failure to lubricate chain
correctly might seem an obvious cause of
early wear, it is still the most common
Fig. 1: Fretting corrosion can result from poor lubrication
Fig. 2: Misalignments can result in side-plate wear
reason for premature failure. Checking your
lubrication regime should be a top priority.
Check that each chain is being lubricated
regularly with the correct lubricant,
referring to the manufacturer’s
lubrication guides.
Fig. 1 shows an example of
conveyor chain where scoring and
heavy red deposits are a clear sign
of fretting corrosion. This is
caused by marginal lubrication
where there is not enough
lubricant present to prevent the
asperities on the chain’s
components rubbing together. In
such a case, lubricate the chain
thoroughly to wash out some of
the oxide, and monitor it
regularly. The chain should then
be lubricated regularly and
correctly to prevent the problem
from recurring.
The transmission chain in Fig. 2
is showing signs of wear on the
face and the end of the sideplates.
The reason for this type of
wear is misalignment, which
causes abrasion with a fixed point
on the circuit. From the wear
pattern, it looks as if the chain
may have worn its guides too, so it
should be easy to spot the point of
contact. The remedy is to realign
the chain before the damage
becomes any more serious and the
chain needs to be replaced.
Renold has produced a free
troubleshooter guide, available as
a downloadable PDF from its Web
site (www.renold.com). The guide
documents dozens of examples of
the sort of conditions that will
cause premature failures, and
provides fix-it advice on rectifying
the problems. Doing this can
increase the chain’s working life
significantly, postpone
replacement costs and cut
downtime.
D&C
When chain does eventually need replacing
there are more opportunities for improving
performance. This will be examined in the
next article in this series.
www.drives.co.uk November/December 2010 37