Note: It is recommended that an ammeter be used as a guide for controlling
the grinding operation. An ammeter monitors the amount of pressure applied
by the Grinding Roll. Excessive pressure can result in chatter marks on
the belt's surface and other undesirable effects.
Start the RB machine at a slow speed, approximately
(5) yards per minute.
Start the grinding roll. Its speed should be approximately
1750 RPM. (NOTE: As a precautionary measure, we recommend that all
subsequent starts of the RB and grinding roll be in the order described
above. Conversely, all stops should be in the opposite order, i.e.,
stop the grinding roll completely before the RB).
- Take note of the "no load" reading of the ammeter. This
varies per machine, but should be close to (5) amps.
Slowly back the compression roll towards the stationary-grinding
roll until the ammeter reads a steady (10-12) amps. Continue grinding
until the ammeter approaches its initial "no load" reading.
HINT: Although NO-TALCâ
Grinding Cloth (Rubber Belt
Maintenance Products) is designed to be used with very little
talc through the course of a RB grind, it is usually a good idea to
add ample talcum powder for the first (10-15) minutes of the grinding
operation. This prevents the grinding cloth from loading up if the
surface of the RB is sticky or gummy.
Continue feeding the RB towards the grinding roll, as
outlined in No. 4 above, until the belt achieves a "new"
Once the RB has this "new" appearance, stop
both the grinding roll and the RB machine, as outlined in No. 2 above,
in order to check the durometer or hardness of the RB.
Using an "A"-type durometer, check the RB
to see if it has reached the desired hardness. (NOTE: The desired
hardness equals the belts original durometer when new. Check the retained
copy of the "Certificate of Compliance" that was included
in the Informational Packet adhered to the belts plastic wrap).
It is very important to check the durometer across the
entire belt width in 50mm (2") increments. Pay special attention
to the hardness of the belt in the selvage area.
For a correct and complete grind, the hardness of the
RB must be returned to its original reading and should be consistent
across the entire width.
If the hardness has not been rejuvenated, continue the
grinding operation until this is achieved.
After renewing the entire surface of the belt, the grinding
roll and RB should be allowed to run with light contact for about
(10-15) minutes, without further feeding of the RB against the grinder.
(NOTE: A light dusting of talc, applied as a lubricant during this
stage, will greatly aid in obtaining a fine surface finish).
After grinding is accomplished, move the RB away from
the grinding roll. Stop both the grinding roll and the RB machine.
Check the RB edges for breaks or cracks and remove any
found. Round off the edges of the RB using a belt or circular sander.
Clean the entire machine, removing all loose rubber
particles and talc from inside and outside the RB and surrounding
Check all rolls, including the guide or stop rolls for
bearing failure. Check all water lines for proper operation and direction
of water flow. (Cross sectional Rubber Belt
unit diagram). Check felt doctor blade or brush for proper position.
Reset Rubber Belt Tension. (Procedure for Tensioning).
Adjust Shrinkage Control Plate to "0" setting.
Use calipers to determine the new thickness of the RB. Move the compression
roll this exact distance from the steam cylinder, being sure both
sides are equal-distant. Move the shrinkage control plate to "0"
Wash the RB (Procedure For Cleaning A Rubber Belt) with
a non-chlorinated soap, such as "Boraxo". (Rubber Belt Maintenance
Products). Cleaning the RB after grinding relieves surface tension,
allowing the cooling water to better adhere to the belt.
Record the RB's thickness and durometer. (Download SHIELDâ
Belt Record keeping format)
THE RUBBER BELT IS NOW READY FOR USE.