LOW PROFILE CONVEYORS
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LUBRICATION OF LOW PROFILE CONVEYORSLow Profile Conveyors utilizing out-dated lubrication technology can have a drastic effect on maintenance and lost production costs. Conveyor Technologies high capacity sealed for life units are still operating on a 24/7 basis after more than (4) years, without re-lubrication. Bearings,
and reducers of the proper type and size, utilizing sealed for life technology,
are providing maintenance free operating life far greater than many systems
requiring routine re-lubrication. Frequently
these routine re-lubrications are neglected, resulting in production disrupted
with an un-anticipated failure. When
this occurs, it is possible that additional components such as pulleys and
shafts that are utilized as the bearing inner race, must also be replaced.
Routine re-lubrication can also expose bearings to harmful contamination,
since this is not performed under the “Clean Room” conditions of the sealed
unit. The
following information was derived from a common manufacturer’s maintenance
manual, and addresses lubrication of bearings on their low profile conveyors.
They recommend removing, flushing, and re-lubricating their driver
bearings every 1,000 hours of operation. A
chart also indicates the lubrication interval based on belt speed. This 1,000
hr. lubrication interval, would require extensive dismantling of drive, and
pulley assembly on a routine basis in order to accomplish this lubrication
procedure. Because of the cost in
time and labor, it is unlikely that many would follow this recommendation.
After reviewing the chart, it becomes apparent that it differs with the
recommended 1,000 hr intervals. At
this point the customer must determine the “interval time” and procedure,
and hope he made the right decision. It is
suggested that these bearings can be lubricated while the conveyor is running.
However, this does not appear to be very prudent, or practical.
This would require holding, and activating a manual grease gun on a
fitting which is only 1/8” of an inch outside the “belt path”.
The closing instructions to wipe off any grease that may have been forced
through the seals, neglects one important issue. Referring to
figure #1, each of these bearings has (2) seals, if grease was forced past the
outer seals, one could assume it may also have been forced past the inner seals,
which are under the belt. Since
this grease cannot be wiped off, it can accumulate and contaminate the belt, and
both pulley surfaces. This has the
potential to cause belt slippage and tracking problems.
Unfortunately the amount of grease forced past these inner seals, and
normally the drive side outer seal, is not externally evident.
This condition is mentioned under the trouble shooting section of their
service manual. Removal of this
lubricant may be difficult, and could require replacing the belt. Because the bearings of the tail pulley are not easily removed, and would normally have to be replaced if they were, the customer appears to have (2) choices. They can replace the entire tail assembly every 1,000 hrs, or select a routine re-lubrication interval, and wait for later replacement. Due to these
greater overall cost that re-lubrication can inflict on the end user, CONVEYOR
TECHNOLOGIES had no hesitation when selecting high capacity, self-aligning,
sealed for life ball bearing units to meet their 2 year warranty. Ball
bearings can normally function twice as long as roller type needle bearings
before re-lubrication is required. The
larger ball bearing used by CONVEYOR TECHNOLOGIES, also has a lubricant capacity
many times that of the needle bearing, and operates at only 70% of the R.P.M. of
these needle bearing units to produce the same belt speed.
The lubrication limitation on needle bearings, plus the lack of axial
load capacity, and self-aligning ability to contend with miss-alignment and
shaft deflection, appears to make them a less desirable choice for a low profile
drive pulley. This may be part of
the reason that bearings are not included in this competitor’s 2,100 hour
warranty. |
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