Unique
Urethane Instant Rollers |
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A
new concept for manufacturing rollers, wheels, and casters
from stock size rollers. Available in 20" standard
lengths with several I.D.'s and O.D.'s, the Dual
Durometer design provides the user with the most economical
"Custom roller" from stock.
Durollers are produced by bonding together two High Performance
PPC urethane compounds. The inner hub is a very hard urethane
(P575 Black) with special additives to produce a self-lubricating
bearing. This is securely adhered to a tough, wear resistant
resistant urethane tire (90A
Red/and 7OA Blue), thus providing superior cut resistance
and shock absorption. For
special applications several other durometers of color-coded
urethanes are available. |
| TYPICAL
APPLICATIONS |
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Car Wash
Rollers |
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Conveyors |
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Wire Guide Rollers
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Conveyor System Drive
Rollers |
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Diverter Rollers on
Package Handling Systems |
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Rollers on Paper and
Plastic Slitting Equipment |
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Equipment |
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Cloth Feed Rollers
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Labeling Machine Rollers
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Driver Rollers in Lumber
Cutting Machinery |
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Glass |
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| ADVANTAGES
OF USING PPC DUROLLERS |
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Lower
Cost - Durollers can be stocked on the shelf
and cut as required, they can be machined on the O.D.
or bored on the I.D. (keyed, grooved etc.) |
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Impact Resistance
- by using urethane elastomers throughout Durollers can
take impact and shock loads without deforming. |
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Dry Running
- in many low PV (Pressure Velocity Co-efficient) applications
no lubrication is needed. In other applications where
a lubricant may contaminate the end product, the use of
Durollers eliminates the problem. |
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Lightweight
- no metal hub and Durollers have been found to be lighter
in weight than aluminum rollers. |
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Ease of Installation
- band or lathe cut to length and insert shaft through
hub and roller is ready to roll. Because of internal lubrication,
there is no need for bearing or grease fittings, or the
worry of scheduled maintenance. |
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Noise Reduction
- since there are no metal components, Durollers are quiet
running and in material handling applications, noise is
significantly reduced especially where metal contacts
metal. |
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Oil and Chemical
Resistance - generally superior to rubber, but
see chart below for more details. |
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Non-Marking
- whereas most metallic and rubber rollers will mark or
scratch surfaces. Durollers will not. |
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Flat Spotting
- Durollers, if left stationary under load tend to recover
more quickly and to a greater extent than rubber. Plastics
and metallic rollers will not recover and will result
in permanent damage. |
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Out-Standing
Temperature Range - Durollers are manufactured
from High Performance urethane elastomers which stand
up to temperatures ranging from -60° to +212°F. |
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| Part Number |
Bearing (Hub) I.D |
Bearing (Hub) O.D |
Roller ( Tire ) O.D |
| 371015 |
3/8" |
1" |
1-1/2" |
| 371520 |
3/8" |
1-1/2" |
2" |
| 501015 |
1/2" |
1" |
1-1/2" |
| 501520 |
1/2" |
1-1/2" |
2" |
| 501525 |
1/2" |
1-1/2" |
2-1/2" |
| 501530 |
1/2" |
1-1/2" |
3" |
| 501540 |
1/2" |
1-1/2" |
4" |
| 621520 |
5/8" |
1-1/2" |
2" |
| 621525 |
5/8" |
1-1/2" |
2-1/2" |
| 621530 |
5/8" |
1-1/2" |
3" |
| 751520 |
3/4" |
1-1/2" |
2" |
| 751525 |
3/4" |
1-1/2" |
2-1/2" |
| 751530 |
3/4" |
1-1/2" |
3" |
| 751540 |
3/4" |
1-1/2" |
4" |
| 102050 |
1" |
2" |
5" |
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| TECHNICAL INFORMATION
AND DESIGN CONSIDERATION |
| Depending on the
pressure (P.S.I.), the coefficient of friction(µ),
is .20 to .30 of its bearing material. Higher pressure relates
directly to a higher µ value. The
nature of the shaft material as well as lubrication will reduce
this value. A Steel that is highly polished (10 RMS finish),
to use an example, will halve the coefficient or friction when
compared to that of a finish of 125 RMS. Reduction in hardness
will cause an increase in the co-efficient of friction of the
tire. Roughening up of the O.D., with an emery cloth or a grinding
wheel can achieve a "grab" to it, to a certain extant,
if the Duroller is required to be a drive wheel. |
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| PRESSURE-VELOCITY
CALCULATIONS (PV) |
| The PV value relates
to buildup of frictional heat and the consequential failure
of the bearing. This is caused by thermal expansion capturing
the shaft, or reaching its melting point. The bearing material
does not serve as a good conductor of heat and is a major constraint
to the Duroller. Use of lubricants, either conventional like
grease or oil, and unconventional such as water, can help greatly
in dissipation of heat, which in turn allows the use of higher
PV values, The PV calculation is based on : |
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If
a given PV value is maintained below 10,000 with maximum pressures
at 600-800 PSI, in full rotation, and with the use of non-lubricated
application, operation should occur problem free.
Surrounding conditions
in the environment may influence this result, wherein PV values
may need to be reduced as temperature increases. All applications
that are intended should first be proven on a trial basis,
since the limits previously shown are only to serve as guidelines.
Load capacities that are outlined by
Polyurethane Products Corporation in this,
should not be exceeded for application with individual Durollers.
Problems may occur with excess deflection. The capacity graphs
should be used and followed as a general rule prior to the
calculations of PV values.
For duro meters other than the
ones shown in the graphs, selection should be based on interpolation
and trials.
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| LOAD CARRYING
CAPACITY |
| As previously
mentioned, the load carrying ability must be determined both
prior to and in addition to the PV limits. The given table shows
three different tire durometers (Hardnesses). The relationship
is based on the deflection that is permissible and the modulus
(PSI) of the tire material. Deflection can be varied by reducing
or increasing load. This can also be achieved by changing the
hardness of the tire material. This may vary upon the application
and whether deflection is desired due to the Duroller conveying
items over the rollers by friction, or for rolling over irregular
surfaces. The opposite holds true to lower durometer materials
causing greater deflection of the tire. |
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| LOAD CAPACITY |
| PV values must
be considered with the loading of Durollers. These are different
from the load capacities of casters and wheels which have metal
hubs and bearings. Once the PV value is in line, you may calculate
load on a particular size of a Duroller with the use of the
chart. This chart may be used to determine the optimal size
Duroller. The chart shows the diameter on the X-axis and the
load capacity on the Y-axis. The load is per inch of face length
at the specified diameter as related to various deflections.
In general, you wouldn't want to design greater than 10% deflection,
because the loads that are required to deflect Durollers to
such an extent, most likely will result in excessive PV values.
Only if bearing grease is supplied to it, or it is used in very
slow application this may be possible. Once again, the chart
serves only as a guide and each application be treated individually
by trial to determine the appropriate load capacity. |
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| OPERATING TEMPERATURES |
The operating
temperatures for the Durollers are suggested in the range of
-60°F (-76°C) to 212°F (1 OO°C). In general
practice, it is recommended that continuous use below -40°F
(-40°C) and above 180°F (82°C) be verified by trial.
Urethanes often become brittle with temperatures below -6Q°F,
as well as, increasing the chance that physical properties may
begin to degrade with temperatures that are at a constant level
above 200°F. However, intermittent exposures up to 225°F
can be tolerated.
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Die-Thane Tooling 
