Product category:
Bearings
News Release from: Igus UK | Subject: Iglidur UW
Edited by the Engineeringtalk Editorial
Team on 29 October 2004
Plain bearings for underwater
applications
New polymer materials promise to outperform graphite bearings in underwater applications.
According to extensive tests performed approximately 2 years ago by an independent pump manufacturer, at that time there was no serious alternative to the large-scale use of graphite bearings In a direct comparison in terms of wear, all plastic plain bearings achieved poorer results
This article was originally published on Engineeringtalk on 9 May 2005 at 8.00am (UK)
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Even when the advantages of polymer bearings were taken into account, replacing graphite bearings was not an option.
Igus has now introduced a completely new bearing that is clearly superior to the wear resistance of graphite bearings.
The new bearing has a minimal wall thickness, with easy assembly and is very robust.
It is also cost efficient, resistant to chemicals and has a good thermal stability compared to graphite bearings.
Its test results were good enough for Igus to launch an extensive development programme with an ambitious aim: find a material that is clearly superior to graphite bearings in terms of resistance to wear under water.
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Determining a suitable location was the first step.
But several preparations had to be carried out in advance: a test bench had to be developed that could be used to test several bearings under water, while simultaneously subjecting the bearings to different loads.
For the duration of the test, which could amount to several months, it was necessary to ensure a constant flow of water around the bearings at all times.
The bearings had to be accessible and easy to replace.
It also had to be easy to check and top up the water level.
All known materials with a good chance of success were then tested.
The results were then used to draw initial conclusions about the structure of the planned, water resistant bearings.
The development of new materials then began: various basic polymers were combined with suitable fillers.
Initially, all new materials had to compete against one another in a long-term endurance test, run over a period of 100 hours, to establish their wear resistance.
Igus discovered a material that reduced the degree of wear found with graphite bearings by a factor of 10.
It was also proven to be extremely abrasion resistant.
The tests had an interesting side effect: in the course of developing this underwater bearing, two types of material performed equally well.
The material Iglidur UW is characterised not only by excellent wear resistance, but also the fact it is very inexpensive.
A cost advantage of more than 50% versus graphite bearings can be achieved for applications in which bearings are required in large quantities.
However, the second material can also be an interesting option for some applications: with this material, the thermal stability is significantly higher, which means that it is appropriate for use on automotive applications, close to an engine.
This material continues to be tested at Igus.
Iglidur UW plain bearings are manufactured as ready-to-install bushes, in almost any size, and comply with pump manufacturer requirements.
However, the test trials still have some way to run.
Now that the endurance tests have been successfully completed, the next step involves researching special features, such as the performance of the plain bearings in saltwater and waste water.
According to Dr Ralf Selzer, Materials Developing Engineer at Igus in Germany: "Trial tests in conjunction with a customer are just as much a part of the test programme as standard tests".
"What the new material can actually achieve can only be proved in practical applications".
"This includes tests in saltwater and in contaminated environments".
"Our customers support us by providing their concrete data, which we can then reproduce in our laboratory".
The material properties of Iglidur UW were tested to analyse the following: thickness, colour, maximum absorption of water at 23C and 50% relative humidity, weight, thermal properties, upper long-term application temperature, upper short-term application temperature, lower application temperature, electrical properties, volume resistance, surface resistance.
The test results available on request from Igus. Request a free brochure from Igus UK ...
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