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News Release

December 4, 2009

Development of long-life, highly corrosion-resistant bearing JHS520 for rolling mill roll necks
~First in series of JTEKT Hyper-Strong(JHS)bearings for steelmaking equipment~

JTEKT Corporation has been pursuing the creation of a JTEKT Hyper-Strong (JHS) series of bearings featuring long life and superior corrosion resistance for use in steelmaking equipment, and as a first product in this series, it has developed the long-life, highly corrosion-resistant bearing JHS520 for rolling mill roll necks.

The improvement of rolling fatigue life and corrosion resistance has been considered necessary in regard to bearings for use in rolling mill roll necks, and concerning this new product, JTEKT succeeded in significantly improving life through application of a newly developed material. In addition, JTEKT provides this new product in both standard and premium specifications to best suit the customer’s machine environment (usage conditions).

JTEKT plans to continue developing bearings for this series, including bearings for continuous forging machines and multistage rolling mills.

Features of developed product

1.Newly developed case-hardened steel

The steel’s alloy-content additive amount was optimized, resulting in significantly improved rolling fatigue, toughness, and corrosion resistance in comparison with conventional steel.

2.Product lineup suitable for various machine environments
  (heavy loads, corrosive environments). 

Suitable for general bearings for steel rolling mill roll neck applications (bearings with outer diameter sizes of φ400 and larger)
 ⇒Can be used as bearing for other applications requiring load resistance capability or superior toughness

Bearing life (*1): Twice that of the conventional product

Greater rolling fatigue life and corrosion resistance than in the case of standard specifications, achieved through application of special heat-treatment
 ⇒Mainly for bearings for the work rolls of cold forging machines for the time being; expansion to other applications planned for the future

Bearing life (*1): Four times that of the conventional product

(*1) Bearing life test
Based on the assumed actual machine operating environment, grease mixed with water is introduced to the bearing interior to induce rust generation, and life testing is carried out.
3.Sales target

 5 billion yen per year
4.Planned customers

 Steel mills and steel plant manufacturers in Japan and overseas

Appearance of developed product

Appearance of developed product