|
|
|
|
|
Manufacture
|
UK
|
South Africa
|
|
Material
|
UHMW1
Polyethylene
|
Polyester
base
|
|
Fillers
|
Unknown
|
Teflon
fibres
|
|
Lubrication
|
Not required though advised by gomog
|
Not required,
water is good lubricant
|
|
Hardness
(Shore D)
|
80
|
82 (slightly
better)
|
|
Linear
thermal expansion (mm/mm/oC)
|
1.42 x
10-4
|
6 x 10-5
(better)
|
|
Water absorption
|
0.1 %
|
0.5 % (same)
|
Ultra High Molecular Weight. Could also be a manufactured Nylon with unknown filler. The are many Nylon grades and it is not possible to determine the exact nature of this type.
At this stage, I believe that both materials would be suitable for the bush application but without further confirmation from Devol, I believe that the Vesconite is more suitable for the application. This material is specifically formulated for dirty environments, is able to take shocks, water-resistant, is used in bearings, ship propellor shaft bearings, mining and transport applications, can be machined and welded.
I have used the Vesconite Hi Lube material in the front suspension beshes, as wear blocks between the rear springs and chassis rails and in the sliding rear spring mounts (Series 1 rear suspension).
A bit of
information found at various sources on the Internet, including Dow Chemicals,
has been added for reference and further confusion.
2.Thermoplastic materials can be remelted and cooled time after time without undergoing any appreciable chemical change.
Abrasion Resistance of Selected Thermoplastics table shows typical abrasion resistance values for a number of selected thermoplastics. Lower values equate with greater abrasion resistance.
1 Grams removed after 100 cycles|
Material
|
Abrasion Resistance %1
|
|
PE Polyethylene)
|
4.5x10-3
|
|
PP (polypropylene)
|
4.3x10-3
|
|
PC
|
4.3x10-3
|
|
Aceta
|
4.0x10-3
|
|
Nylon 6/6
|
1.6x10-3
|
|
PU
|
1.5x10-3
|
The Ranking of Selected Thermoplastics
by Hardness table shows the relative ranking of major thermoplastics from
softest to hardest.
|
Ranking
|
Material
|
|
Softest
|
HDPE (high density polyester)
|
|
|
ABS (Acrylonitrile Butadiene Styrene)
|
|
|
Polysulfone
|
|
|
PBT
|
|
|
PC
|
|
|
GPPS
|
|
|
PET (Polyethylene Terephthalate)
|
|
|
Acrylic
|
|
|
Nylon 6
|
|
Hardest
|
Thermoplastic Polyimide
|
3.Coefficient of Friction: -
The coefficient of friction, determined by ASTM D 1894, numerically represents the resistance to movement when moving against another surface. Values are given for both static friction (the limiting friction between surfaces just before motion occurs) and kinetic friction (the friction after motion has occurred). The coefficient of friction is the ratio of the limiting friction to the normal reaction between the moving surfaces.
The Typical Coefficient of Dynamic Friction of Selected Plastics vs. Steel table lists the dynamic coefficient of friction of selected thermoplastics against steel surfaces. The lower the value, the "more slippery" the material.
|
Material
|
Coefficient
|
|
PC
|
0.55
|
|
ABS
|
0.5
|
|
SAN
|
0.5
|
|
Nylon
|
0.4
|
|
PMMA
|
0.4
|
|
PS
|
0.4
|
|
PPE
|
0.35
|
|
PP
|
0.33
|
|
HDPE
|
0.26
|
The Devol site can be located at - http://www.devol.com/material/Fdev.htm
Click Design Criteria above and then bushes and bearing and then "properties".
The Vesco site can be located at – http://www.vesco.com.au/vescoplastics.html
About Plain Bearings, P max, V max, and PV max
Sleeve Bearing
P max- The maximum load a bearing can carry at 0 rpm.
Formula: Maximum bearing load (psi for inch sizes; N/mm2
for metric) = P max x bearing length x shaft diameter
To convert psi to N/mm2 , multiply psi value by 0.006894757. To convert N/mm2 to psi, multiply N/mm2 value by 145.032.
V max- The maximum velocity or speed (based on the maximum
shaft rpm) that a bearing can carry at light loads. For inch bearings,
maximum velocity is stated in surface feet per minute (fpm). For metric
bearings, it is meters per second (m/s). To convert fpm to m/s, multiply
fpm value by 0.00508. To convert m/s to fpm, multiply m/s value by 196.8504.
PV max -Once you've selected a bearing based on
P max and V max, use PV max (shown with product listings) as the final
check to ensure that the bearing can sustain your combined load and speed
requirements. If actual PV is less than PV max, the bearing should fit
your application.
Bronze Sleeve Bearings
For Shaft Dia. Tolerance
For
Shaft Dia. Tolerance
SAE 841
1/8"-1 1/2" +.000" to -.001"
1 3/4"-2 1/2" +.000" to -.0015"
3" +.000" to -.002"
SAE 660
All ±.0010"
Metric SAE 841
All +.006 to +.024mm
Metric SAE 660
All ±.0254mm
OD Tolerance
OD Tolerance
SAE 841
1/4"-1 5/8" +.000" to -.001"
1 3/4"-2 3/4" +.000" to -.0015"
3"-3 1/2" +.000" to -.002"
4" +.000" to -.003"
SAE 660
1/4"-3" +.002" to +.003"
3 1/2"-4" +.003" to +.005"
Metric SAE 841
15-18mm +.028 to +.046mm
19-22mm +.035 to +.056mm
Metric SAE 660
All +.0508mm to +.0762mm
Length Tolerance
Length Tolerance
SAE 841
1/8"-1 1/2" ±.005"
1 3/4"-3" ±.0075"
4" ±.010"
5"-6" ±.015"
6 1/2" Not rated
SAE 660
All ±.005"
Metric SAE 841
All ±1%
Metric SAE 660
All ±.1270mm
SAE 841 Bronze- Similar to Oilite-style bushings with
an alloy of copper, tin, and carbon, these porous sintered bronze bearings
are vacuum-impregnated with 18-20% SAE-30 oil. Heat created by shaft movement
draws the oil to bearing surface. The oil acts as a cushion between the
shaft and bearing, reducing wear and increasing resistance to shock loads.
SAE 660 Bronze- An alloy of
copper, tin, lead, and zinc, these nonporous bearings resist shock loads
and wear. High-temperature lubricants are recommended over 250° F.
Bearing Material Temperature Range For Shaft
Hardness Pmax Vmax PVmax
SAE 841 10° to 220°F Medium and up
2,000 1,200 50,000
SAE 660 10° to 450°F Medium and up
4,000 750 75,000
Metric SAE 841 10° to 220°F Medium and
up 13.79 6.10 1.75
Metric SAE 660 10° to 450°F Medium and
up 27.58 3.81 2.7