Special Issue; Products for Industrial Machinery - NTN

NTN TECHNICAL REVIEW No.742006
New Product
The Rust Guard Bearings
of Highly Corrosion-resistant Bearings
Takashi YAGI
The environment of bearings for steel mill machinery has
recently become more severe. For example, the time intervals
between machine maintenance has increased and the
composition of the water used in the rolling process varies. Lastly,
there is a growing demand for long-life bearings for the steel mill
industry. To combat these tough conditions, NTN has developed
the Rust Guard bearings of highly corrosion-resistant bearings.
This publication describes the Rust Guard bearings in detail.
1. Introduction
The steelmaking industry worldwide has recently
been undergoing a strong restructuring drive to ensure
the availability of iron resources, including iron ores,
and to prevent the oversupply of steel products in the
future. To accomplish this, the production lines in
present-day steel mills are being used to their full
capacity, while extending maintenance intervals for
steel mill machinery in order to improve productivity.
The durability of the bearings used in various
applications in steel mills, such as the production and
transportation machinery for raw materials and steel
products, directly affects the productivity of such
machinery. If a bearing failure occurs in an
unexpectedly short time (hereafter referred to as
“premature failure”), a long time is necessary for
restoration and significant monetary loss results. NTN
has developed the RustGuard bearing line of highly
corrosion-resistant roll neck bearing products for
rolling lines where damaged bearings can greatly
affect the operability of production lines. The goal in
developing the RustGuard line is to prevent the
premature failure of bearings.
2. Background for Developing
RustGuard
Flaking, which is a typical bearing failure, can be
categorized into flaking that starts internally, in which
fissures start inside immediately below the raceway
Photo 1 View of a Rolling Mill in the Rolling Process
Fig. 1 Cross-sectional View of a Roll-neck Bearing
on a Rolling Mill
surface, and flaking that starts from the surface, in
which flaking begins at damage on the outermost
raceway surface. Many cases of premature bearing
failures result from flaking that starts on the surface.
Therefore, flaking that starts on bearing surfaces must
be actively inhibited to ensure reliable operation of the
rolling lines in steel mills.
Industrial Engineering Dept. Industrial Sales headquarters
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