LOW PROFILE CONVEYORS
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WHY
Often when
reviewing low profile conveyor literature I am confronted with tantalizing
statements such as, “OUR CONVEYORS ARE
BUILT TO LAST” “OUR
PRODUCTS ARE BASED ON THE VOICE OF OUR CUSTOMER”
“CUTTING EDGE TECHNOLOGY” “FASTEST
BELT CHANGE ON THE MARKET” “DESIGNED
TO VIRTUALLY ELIMINATE MAINTENANCE”. After
reading this, one might assume that
these companies have obtained perfection. Why then would a
conveyor manufacturer continue using needle bearings to support a
drive pulley, when they should realize the limitation of these bearings?
Instead they recommend keeping replacements on hand, and exempt bearings
from their warranty. Needle bearings
have no self-aligning feature to prevent non-uniform loading, nor do
they have any practical axial load capacity.
They have a minimal lubrication capacity
and on average, require twice the lubrication frequency of ball bearings.
Even if lubrication were not a factor, this application could result in a
reduced bearing life due to excessive needle loading, induced by pulley
miss-alignment, deflection, and creep. Because
this is not a self
contained sealed bearing element it can be subject to contamination during
assembly and maintenance. Integrity
of the bearing inner race (pulley) may also present a problem since it is not a
product of the bearing manufacturer. This
doesn’t appear to be CUTTING EDGE TECHNOLOGY. WHY would this manufacturer claiming “THEIR
PRODUCT IS BUILT TO LAST” not
use a totally self-contained sealed bearing unit?
Using the pulley shaft as a wearing bearing element can be expensive for
the end user. Bearing failure may
require replacement of not only the bearings, but also the more expensive pulley
which acts as the bearing inner race.
Not replacing the pulley means the new bearings may
be installed on a worn inner race, which
can have a negative effect on their life. WHY do these conveyor manufacturers utilize
pulley diameters close to the minimum recommended for much of the belting used,
when it has a negative effect on belt, and cleat
fatigue life, and a drastic effect on bearing life?
Is this really “THE
VOICE OF THEIR CUSTOMER”? WHY would a conveyor manufacturer’s “CUTTING
EDGE TECHNOLOGY” require
re-lubrication of bearings, and oil changes on gear reducers when sealed for
life bearings, and reducers have, on average, demonstrated improved life over
these out dated systems for years? WHY would a conveyor manufacturer claiming
their product is “DESIGNED
TO ELIMINATE MAINTENANCE”, equip
their pulleys with a sharp diamond knurl when
it is well known this can cause belt abrasion, and is not recommended by most
belting manufacturers? They then
reveal in their service manual that residue can build up
on the knurl causing miss-tracking and belt slippage, and recommend cleaning the
knurl, (which requires removing the
belt or pulley). They also suggest
if the knurl is worn, the pulley
should be replaced to avoid belt slippage. Then,
depending on the age of the conveyor,
new bearings, and bearing plates, may be required. This company also
advocates stocking complete drive and idler kits. WHY would a conveyor manufacturer utilize a
small conveyor resting on a bench or installed in a non-functioning position in
a demonstration fixture, not encumbered with being bolted to stands or a machine
base, and free from any obstructing side rails, or functioning drive, and then
claim a one to five minute belt change? Do
they really think their customers,
who take up to 60 to 90 minutes to change a belt on their real world conveyor
installation, are going to accept this statement of
“FASTEST BELT CHANGE ON THE MARKET”? WHY would anyone not offer a “crowned
pulley” which is recommend by all belting producers, and
provides an automatic wear resistant tracking system?
The use of only a bottom vee guide which adds a major wear point to the
belt, and offers no non-contact corrective action, can result in reduced life of
a more expensive belt. Does this
really ELIMINATE MAINTENANCE? WHY are all these items which have such a
negative effect on performance, reliability and cost, being camouflaged with
these tantalizing statements? The December 2006 issue of a Popular Publication contained an article relating to “IMPLIED QUALITY” that offers a possible explanation for this camouflage. The author states that many Companies put more effort into creating an “IMAGE” of quality, rather than trying to achieve this quality. He goes on to say that sadly, this makes sense because saying you have “HIGH – QUALITY” is easier, and cheaper than actually achieving this “IMPLIED QUALITY”. Maybe now we have one answer to “WHY.” |
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