Q&A – Super Precision Bearings
Here at NSK we genuinely believe that we offer the highest quality Super Precision Bearings on the market.
In this Q&A, we sit down with Product Manager Andy Kemble, to find out what makes these components, manufactured in Newark, England, standout from the competition.
Andy has been part of the NSK engineering team for over thirty years and boasts a deep understanding not just of Super Precision Bearings, but of the industries and applications where they are found.
"What defines a Super Precision Bearing and how do these bearings differ from their more standard counterparts?"
A Super Precision Bearing (SPB) is defined simply as a product made to ISO Precision Class 5 (P5) tolerances or better. So that includes Class 4 (P4), Class 2 (P2) and various special NSK specifications such as P3. These superior tolerances give tighter control over external dimensions and running accuracy compared to a standard industrial class bearing. The benefit of this is greater bearing operational consistency, lower vibration and higher speed capability (in conjunction with tailored internal design features).
"SPBs are essential to the machine tool sector. How does NSK cater to the unique demands of this sector?"
A Super Precision Bearing (SPB) is defined simply as a product made to ISO Precision Class 5 (P5) tolerances or better. So that includes Class 4 (P4), Class 2 (P2) and various special NSK specifications such as P3. These superior tolerances give tighter control over external dimensions and running accuracy compared to a standard industrial class bearing. The benefit of this is greater bearing operational consistency, lower vibration and higher speed capability (in conjunction with tailored internal design features).
"What are the key features which make NSK’s bearings the top quality product on the market?"
The main fundamental component of SPBs is steel, and NSK has established groundbreaking technologies in its manufacture and the evaluation of non-metallic inclusions, extending life and enhancing bearing performance. Three signature steels are used in NSK SPBs: Z steel for extended life under normal conditions, SHJ steel for high reliability under heavy loads or contaminated conditions, and SHX steel for ultra-high-speed rotation. Combined with NSK’s specialist bearing manufacturing technology and extensive product design expertise, it enables delivery of bearings to the highest level of quality in the world.
"What do these bearings offer to the end user?"
High quality bearings offer high reliability. This means that, in addition to the high-performance characteristics offered by NSK SPBs, we also deliver peace of mind that they can be relied upon time and time again. This is supported by NSK simulation and testing, enabling extended machine tool service intervals and hence less downtime, which ultimately saves end-users time and money, and minimises the impact on the environment.
"How does NSK ensure we avoid and overcome common pitfalls for bearings like these?"
We employ rigorous design and supplier approval processes, both supported by many years of experience. Combined with our inhouse manufacturing expertise, this approach is used globally within NSK which ensures consistency. This means that anyone buying any type of NSK SPB can rest assured regarding its quality and performance.
"What testing or validation methods does NSK use to qualify super precision bearings for extreme-speed conditions?"
Ultra-high-speed bearing developments are validated in NSK by numerical simulation and by representative testing. Such test rigs are designed not only for ease of assembly and disassembly, but also to have the capability of the highest speed motorised machine tool spindles. This enables absolute performance confirmation and the illustration of comparative performance to previous or alternate designs.
"Are you seeing any shifts in demand towards certain types of product or for certain attributes?"
As the operating demands on machine tools have increased, the need for advanced bearing materials has also gone up. As already mentioned, NSK offers three signature steels to help meet these needs. In addition, we are increasingly utilising silicon nitride (ceramic) balls for the most arduous of conditions. Ceramic balls are lighter, have a lower coefficient of thermal expansion and a higher modulus of elasticity than steel balls. When applied to hybrid bearings, the benefits are lower centrifugal force, lower friction and higher stiffness, resulting in lower heat generation (which enables increased speed capability), improved seizure resistance and higher rigidity. This also gives the added benefit of extending bearing life with grease lubrication. The NSK manufacturing process for ceramic balls enables a higher level of accuracy than with steel materials, facilitating high accuracy machining for the end-user.
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