Product category:
Bearings
News Release from: NSK UK | Subject: SWR bearings
Edited by the Engineeringtalk Editorial
Team on 05 November 2003
Novel bearings have twice the life
The new SWR super-wear-resistant bearing boasts more than twice the life of conventional bearing types.
NSK has succeeded in developing a longer life spherical roller bearing for use in the guide rolls of continuous casting machines The new SWR super-wear-resistant bearing has more than twice the life of conventional (SUJ2) bearing types
This article was originally published on Engineeringtalk on 5 Jun 2006 at 8.00am (UK)
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Bearings boast maximum wear resistance
Designed for use in the guide rolls of continuous casting machines, Super Wear-Resistant bearings have more than twice the life compared with conventional (SUJ2) bearing types.
Guide helps users avoid bearing failures
Free publication deals with all aspects of bearing procedures, including handling of bearings, mounting, maintenance and inspection, dismounting and bearing storage.
In field tests the SWR bearing has proven to be superior not only in wear resistance, but also in surface originated flaking life characteristics and core toughness.
As a result, NSK plans to develop SWR technology for use in other industries, in addition to steel, where low rotational speeds result in high levels of bearing wear.
The spherical roller bearings used in the guide rolls of continuous casting machines operate under some the most severe conditions imaginable: heavy load, ultra-low-speed rolling (only a few rotations per minute), and an environment of water and scale contamination.
As a result of these conditions, the bearings often suffer from uneven wear on their outer ring raceways, leading to the development of cracks and flaking.
In some cases the flaking results in outer ring fracture, causing the bearing to fail, sometimes with very serious implications for continuous steel production.
Further reading
Positioning technology allows microscopic handling
NSK's micro-manipulation system features a three-axis (XYZ) positioning stage that facilitates the attachment of measuring devices, micromanipulators and microscopes for examining a preparation.
Guide eases bearing changes
The guide provides replacement part numbers for metric bearings in bore diameters from 2 to 220mm and imperial sizes from 1/8in bore to 57.15in.
Bearing replacement saves money for fish processor
NSK's Silver-Lube bearings are designed specially for use in industries where hygiene considerations and corrosion and chemical resistance are important.
A number of countermeasures have been tried in an attempt to overcome the above problems of wear and premature failure.
Improved lubrication via oil-air systems is one, but this method is not practical due to the prohibitive cost of making modifications to existing equipment.
Another is the use of cylindrical roller bearings, specially designed to avoid differential slide.
However, this type of bearing is applicable only to one side of the roll since it cannot carry the axial load.
The inherent drawbacks with these measures led NSK to take a newer and more radical approach to the problem: to develop a bearing whose life could be extended by means of the latest materials and heat treatment technologies.
The advantage of this approach was not only the promise of longer wear life and higher resistance to failure, but also that the newly developed bearing would conform to industry standard dimensions and would therefore fit existing equipment and housings without modification.
The development of the new longer life bearing involved NSK in producing a new type of steel, one which provides superior wear resistance under severe lubrication conditions and also high resistance to surface originated flaking.
NSK was the first in the world to prove that an increase in retained austenite is the most effective solution for improving the surface originated flaking life characteristics of bearings under such severe lubrication conditions.
Further research then revealed that even more effective results were achieved when increases in the level of austenite in a material were matched by increased levels of hardness.
This knowledge was first applied successfully to producing NSK's unique life extension TF technology, and now this same technology has been applied in the development of a new material for SWR bearings.
The second key element in the development of the new longer life SWR material is NSK's carbo-nitriding technology.
NSK was the first bearing company to successfully apply this technology to rolling bearings.
The benefit of carbo-nitride technology is that produces large amounts of fine, hard particles in a material, which provide superior resistance to wear.
The newly developed steel being case hardened, has a toughness about five times that of SUJ2 through hardened steel.
The benefit of this operation is that it allows the compressive residual stress in the surface layer of the SWR bearing material to function effectively, providing high resistance to flaking, and helping to prevent outer ring fractures.
In view of the fact that the main area of damage for bearings used in continuous casting machines is the bearing outer ring, NSK has applied the newly developed SWR exclusively to this area.
Application of the material to the bearing inner ring and rollers was avoided, the reason being that the use of different materials for parts that come into contact with each other is key to the effectiveness of SWR bearings.
In water contaminated lubrication wear tests the combination of the newly developed SWR bearing steel and conventional steel provided the best results, proving that a material combination is of extreme importance when the entry of water is expected.
SWR material also demonstrated superior performance under debris contaminated lubrication conditions using a thrust type life tester.
When compared on the basis of the 1L10 life, at which the cumulative damage probability becomes 10%, the life of the newly developed SWR steel is about five times longer than that of conventional steel.
Following the excellent results obtained from in-house testing, NSK undertook field evaluations of SWR bearings on continuous casting lines in co-operation with several major steelworks.
The results of these evaluations showed that SWRTM bearings provided two to three times more life when compared with conventional bearings.
As a result of this success SWR bearings are set to make a real contribution to the extension of maintenance cycles on continuous casting machines, and to promote greater efficiency of production through the superior characteristics of flaking resistance and ultimate fracture resistance. Request a free brochure from NSK UK ...
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