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Frequently Asked Questions - FAQ
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- What is the UV Resistance of Vesconite?
- Does Vesconite have FDA or USDA approvals for use with food?
- Can Vesconite be used immersed in oil? Will Vesconite swell in oil?
- Do you provide warranties?
- How does Vesconite compare with phosphor bronze?
- How does Vesconite compare with Nylon?
- How does Vesconite compare with Acetal (POM) ?
- How does Vesconite compare with Ultra High Molecular Weight Polyethylene, UHMWPE?
- How does Vesconite compare with phenolic laminates?
- Can Vesconite be used instead of polytetrafluroethylene, PTFE?
- How does Vesconite compare with PTFE, acetal and bronze coated steel strip bearings?
- How does Vesconite compare with underwater cutless bearings (rubber, nitrile)
- How does Vesconite Hilube compare with Vesconite?
- How does Vesconite Hilube compare with glass filled PTFE?
- How does Vesconite Hilube compare with lubricated nylons?
- How does Vesconite Hilube compare with acetal and PTFE / Teflon filled acetals?
- How does Vesconite Hilube compare with oil filled bronze?
- How does Vesconite Hilube compare with PTFE, acetal and bronze coated steel strip bearings?
- Can Vesconite Hilube be used instead of PTFE?
1.
What is the UV Resistance of
Vesconite?
The UV resistance of Vesconite is excellent.
Many pieces of Vesconite have been exposed to tough sunlight and
environmental conditions for over 30 years, and remain in excellent
condition.
2.
Does Vesconite have FDA or USDA approvals for use with food?
Vesconite and Vesconite Hilube are
manufactured from materials and ingredients that have no known health
effects. Further, neither material contains asbestos.
Both materials as a result of a series of stringent tests have been approved for direct contact with drinking water in potable water applications in terms of the UK Water Regulations Assessment Scheme. See Approval for Drinking water applications for full details.
T
hese drinking water approvals extend to both ambient and hot drinking water applications for both materials.It may be noted that the hot drinking water tests represent a much more challenging test, one which is far harder to meet than the cold water test.
When considering the question of food contact approval for Vesconite and Vesconite Hilube, one should ask is there going to be any direct contact between the Vesconite or Vesconite Hilube and the foodstuffs concerned?
In many applications there is no specific foodstuff contact, because of the nature of the design of the equipment. This often means that the need for approval may fall away.
A major advantage of Vesconite and Vesconite Hilube bearings in food processing applications is that they usually do not require greasing. This greatly simplifies maintenance, allows for much cleaner and simpler operation, and reduces costs as food approved greases tend to be expensive.
Vesconite and Vesconite Hilube also represent a major advantage over metallic bearings such as those made from bearing bronzes, which often contain lead and tin, a concern in food processing applications.
It should also be considered that Vesconite and Vesconite Hilube may often replace metallic or polymer wear parts which did not have any specific foodstuff approval for the application.
To date one specific approval for a food contact application was required, namely for ice making machinery (yes, ice may be considered a food!). Approval was granted by the regulatory authority concerned.
3.
Can Vesconite be used immersed in oil? Will Vesconite swell in oil?
Vesconite has excellent resistance to a wide range of chemicals
including oils and fuels, hydrocarbons, gasoline (petroleum), many
acids, organic chemicals and solvents.
Vesconite remains hard in a wet environment. Its performance in water and other liquids is unrivalled. Vesconite absorption of oil, the above chemicals or moisture is negligible and it does not soften.
Vesconite has been used in hundreds of oil, fuel and water immersed applications with great success.
Vesconite remains hard in immersed conditions and keeps its compression strength and excellent resistance to creep. Vesconite maintains its excellent long life wear characteristics whether wet or dry.
Many synthetic bearing materials, like those based on elastomers and
nylons, absorb these chemicals, soften and lose their compression
strength in immersed conditions.
Vesconite Consultant.
4.
Do you provide warranties?
Our conditions of sale include a limited warranty that goods
are supplied on the express condition that the Company's liability is limited to
the replacement of defective goods or materials.
We do not provide more extensive warranties as we do not have any control over the way our materials are used, where the following factors amongst others are important:
a) How the materials are installed
b) The condition of the journal counter surfaces that they run against
c) The specific alloys used for metal journals
d) The relative bearing surface speeds
e) The bearing pressure
f) The extent or frequency of lubrication provided
g) The type of lubricant
h) The level of dirt or abrasives that are present at the bearing interface
i) The clearances or press fits provided.
All of these aspects can dramatically affect the performance of Vesconite
bearings. The years of experience of VescoPlastics gives us the ability to
advise on these aspects in order to maximise performance.
Many materials give excellent results under laboratory
conditions, but these results are not as good under actual conditions. A feature
of Vesconite is that it performs well under actual conditions.
Our materials are used successfully in thousands of different applications,
including in the commercial marine industry, in railways, in heavy duty
transport, in earth moving plant, in pumps, in manufacturing, in deep level
underground mines.
Our material are used in over 50 countries on every continent. We are of the
view that there could be endless disputes if we were to provide warranties, as
warranties could so easily be abused in many situations far beyond our reach
where we do not have any control over so many factors.
5. How does Vesconite compare with
phosphor bronze?
Vesconite shows half the friction of bronze,
is able to operate without grease oil and operates very effectively under water.
Vesconite can give up to 10 times longer life under dirty conditions.
The cost of Vesconite has become increasingly competitive against bronze.
Vesconite cannot handle as high speeds, as lower heat dissipation can result in overheating.
Bronze can handle higher operating temperatures, whereas Vesconite is typically limited to 100-120°C Back to top
6. How does Vesconite compare with Nylon?
Vesconite has much higher wear resistance, higher
load carrying capacity and higher surface speed limits than nylon, owing to Vesconite's
greater compression strength, higher hardness and lower friction.
Vesconite is dimensionally stable, so tight clearances are maintained.
Vesconite's water absorption is negligible compared with 9% for nylon, which causes up to 3% swell of nylon.
Vesconite's thermal expansion is nearly half that of nylon. Vesconite does not swell and soften like nylon, due to moisture absorption from its atmosphere or wet environments. Thus seizure caused by swelling due to moisture, which is often a problem with nylon, is not experienced with Vesconite.
Vesconite can be used with much finer tolerances and clearances, owing to much better dimensional stability.
Vesconite's chemical resistance to acids and solvents is much better.
Vesconite machines more easily.
Vesconite causes less wear to shafts and pins than nylon.
Vesconite does not have as good resistance to alkalis and to hot water/steam as nylon.
Some data on nylon 6 vs Vesconite:
| Design loading: | Nylon 20 MPa / Vesconite 30 MPa |
| Thermal expansion: | Nylon 10 mm/mm/°C x 10-5 |
| Vesconite 6 mm/mm/°C x 10-5 | |
| Water absorption (saturated): |
Nylon 9% / Vesconite 0.5% |
| Maximum recommended continuous operating temperature: | Nylon 80-100°C / Vesconite 100-120°C |
7. How does Vesconite compare with Acetal (POM) ?
Vesconite has much higher wear resistance.
Vesconite has
higher load carrying capacity and higher surface speed limits and hence PV
limits than acetal.
Vesconite has better dimensional stability and lower friction.
Vesconite can be used with much finer tolerances and clearances, owing to much better dimensional stability.
Vesconite's chemical resistance to acids and solvents is much better.
Vesconite machines more easily.
Some data on polyacetal (POM) vs Vesconite :
Tensile yield strength = acetal 65MPa / Vesconite 80 MPa
Design loading = acetal 25 MPa / Vesconite 30 MPa
Thermal expansion = acetal 10 mm/mm/°C x 10-5 / Vesconite 6 mm/mm/°C x 10-5
Water absorption (saturated) = acetal 0.8% / Vesconite 0.5%
Maximum operating temperature continuous = acetal 100°C / Vesconite 100-120°C Back to top
8. How does Vesconite compare with
Ultra High Molecular Weight Polyethylene, UHMWPE?
Vesconite has much higher load limits and
much greater dimensional stability due to its much greater compression strength and much
lower thermal expansion
Vesconite is suitable for higher speed operation and high load applications.
Vesconite is available in a much wider range of bushings, bushes and moulded semi- or finished parts.
Vesconite has lower impact strength and flexibility.
Some data on UHMWPE vs Vesconite:
Maximum design loading = UHMWPE 10 MPa / Vesconite 30 MPa
Thermal expansion = UHMWPE 20 mm/mm/°C x 10-5 / Vesconite 6 mm/mm/°C x 10-5
Maximum operating temperature continuous = UHMWPE 50°C / Vesconite 100-120°C Back to top
9. How does Vesconite compare with
phenolic laminates?
Vesconite has a longer wear life.
Vesconite has lower friction and is better able to operate without lubrication, with lower wear.
Vesconite is not subject to delaminating, which is often a problem with underwater bearings.
Vesconite costs less.
Vesconite is limited to temperatures of 100 to 120°C.
Vesconite has a higher thermal expansion coefficient.
Some data on Phenolic laminates vs Vesconite:
Maximum design loading = phenolic laminates 40 MPa / Vesconite 30 MPa
Thermal expansion = phenolic laminates 2 mm/mm/°C x 10-5 / Vesconite 6 mm/mm/°C x 10-5
Water absorption (saturated) = phenolic laminates 1% / Vesconite 0.5%
Maximum continuous operating temperature = phenolic laminates 130°C / Vesconite 100°C Back to top
10. Can Vesconite be used instead of
polytetrafluroethylene, PTFE?
Vesconite is a far superior bearing material. It can take very
much greater loads, and is far more resistant to wear, and in particular resistant to
dirt.
PTFE is often used in aggressive chemical environments, which Vesconite may not be able to withstand. Back to top
11.
How does Vesconite compare with PTFE, acetal and bronze coated steel
strip bearings?
Vesconite has much longer wear life, especially in the
presence of dirt.
Vesconite is better suited to underwater operation, and for speed and
dynamic applications.
The wear of Vesconite is not limited to a thin superficial wear layer
0.05 to 0.3 mm thick. Once this layer on a metal strip bearing is worn, there is
steel to steel contact which results in high wear and possible shaft damage.
Vesconite can be machined to any size and shape, as required, as it is
available in a wide range of stock shapes in rod, bushing and plate.
Vesconite generally is price competitive, especially for larger bearings.
Vesconite has lower heat transmission and is generally not suited to
applications >120°C. Back to top
12. How does Vesconite compare with underwater cutless
bearings (rubber nitrile)?
Vesconite gives a longer service life than
cutlass bearings at a lower cost
in clear/blue water conditions.
Vesconite results in lower wear on the shaft.
Vesconite has a much lower friction.
In dirty conditions, for example rivers, Vesconite has given promising long life results when used together with hardened shafts or shaft sleeves. Contact us for more information. Back to top
13.
How does Vesconite
Hilube compare with Vesconite?
The friction of Vesconite Hilube is nearly 50% lower than Vesconite,
similar to glass filled PTFE.
Vesconite Hilube's wear in unlubricated and underwater conditions is 75% lower
with double the PV limit of Vesconite.
Vesconite Hilube has no slipstick effects. Back to top
14.
How does
Vesconite Hilube compare with glass filled PTFE?
Vesconite Hilube is priced lower, and has better wear resistance
particularly in dirty conditions.
Vesconite Hilube can be injection moulded and extruded instead of being pressed.
Vesconite Hilube cannot withstand corrosive chemicals.
PTFE has excellent chemical and high temperature resistance. Vesconite Hilube is
resistant to fairly high concentrations of acids, but is not resistant to
alkalis. The typical maximum operating temperature in non-immersed applications
is 100° to 120°C. Back to top
15.
How does
Vesconite Hilube compare with lubricated nylons?
Vesconite Hilube has much lower friction, higher PV limit and is
better suited for dry or underwater operation.
Vesconite Hilube has a much higher load bearing capacity, negligible water
absorption and much better dimensional stability.
Vesconite Hilube has much higher chemical resistance to acids, but lower
resistance to strong alkalis and steam, and lower impact strength.
Back to top
16.
How does Vesconite Hilube compare with acetal and PTFE / Teflon filled acetals?
Vesconite Hilube has a lower dynamic friction and superior wear
performance. Vesconite Hilube's lower thermal expansion means that it is more dimensionally
stable and tight clearances can be held over a wider temperature range.
Vesconite Hilube has a higher loading strength and higher melting point.
Back to top
17.
How does
Vesconite Hilube compare with oil filled bronze?
The built in lubrication in Vesconite Hilube remains effective
indefinitely, whereas oil filled bronze bearings tend to "dry out" and lose
their lubricity with time.
Vesconite Hilube is very suitable under water.
Vesconite Hilube has a lower wear rate and longer wear life.
Vesconite Hilube has a lower PV limit due to its higher thermal expansion.
Vesconite Hilube requires slightly larger clearances. Back to top
18.
How does Vesconite Hilube compare with PTFE, acetal and bronze coated steel
strip bearings?
Vesconite Hilube has much longer wear life, especially in the
presence of dirt.
Vesconite Hilube is better suited to underwater operation, and for speed and
dynamic applications.
The wear of Vesconite Hilube is not limited to a thin superficial wear layer
0.05 to 0.3 mm thick. Once this layer on a metal strip bearing is worn, there is
steel to steel contact which results in high wear and possible shaft damage.
Vesconite Hilube can be machined to any size and shape, as required, as it is
available in a wide range of stock shapes in rod, bushing and plate.
Vesconite Hilube generally is price competitive, especially for larger bearings.
Vesconite Hilube has lower heat transmission and is generally not suited to
applications >120°C. Back to top
19.
Can Vesconite Hilube be used instead of PTFE?
Vesconite Hilube is a far superior bearing material. It can take very
much greater loads, and is far more resistant to wear, and in particular resistant to
dirt.
PTFE is often used in aggressive chemical environments, which Vesconite Hilube may not be able to withstand. Back to top
Updated Feb 19 2004
