Increased Efficiency for Steel Mills with NSK Innovations

23 August 2019

NSK Ltd. has developed a four-row sealed tapered roller bearing with water resistant grease. The tough environments found in steel mills require components that can withstand the challenging conditions as well as contribute to keeping cost and energy consumption down. New work roll bearings for rolling mills1 from NSK offer greater reliability and longer service life.

NSK work roll bearings are packed with a newly developed grease that extends service life even under severe conditions, including water inclusion. The new grease composition offers a thicker oil film and protective layer between the raceway and rollers. Grease additives also inhibit corrosion which boosts the service life in conditions where water has potential to enter the bearing.  Increased service life equates to reduced maintenance costs and increases operational efficiency. In addition, with reduction in need for replacement, CO2 emissions and resource consumption are also reduced.

1Rolling mills typically use pairs of work rolls to roll slabs of steel or other metals into specific shapes such as sheets.

Development Background

In addition to contending with extreme environments, work roll bearings carry heavy loads at high speeds and temperatures while under constant exposure to water sprays and metal particles. These severe conditions can lead to premature bearing failure due to damage conditions such as flaking. Flaking occurs when fatigue causes small pieces of bearing material to break away from the smooth surface of the bearing raceway, creating coarse regions within the bearing that can eventually make bearing inoperable. Failures can also result from rust and water, used for cooling, entering the bearing and potentially causing seizure. In effort to increase reliability and ensure long service life, NSK has designed a special seal that helps to keep out water and other particles.

The newly designed sealed bearing offers two benefits. With an optimized internal design, an increase in load rating is achieved. Additionally, the improved seal design inhibits water from entering the bearing which can reduce contamination of the grease and improve bearing performance.

With these two significant improvements, real world test validated dramatic gains in bearing service life. For example, bearings in a specific mill are now achieving 16 months service life compared to conventional bearings typically lasting less than 8 months.

Product Benefits

Increased service life equates to higher operational reliability, fewer replacements and reduced downtime for repair. Longer service life also reduces material and energy consumption (including CO2 emissions) relative to the replacement cycles of conventional models.

NSK continues to develop and produce new products geared toward realizing a sustainable society. For more information please contact [email protected]

Established in 1916 and headquartered in Tokyo, Japan, NSK is a world-class manufacturer of motion and control products. NSK produces and distributes a wide range of rolling element bearings, linear motion and automotive component products for a variety of industries and applications.

Operating in the Americas, NSK Corporation is a member of the NSK Ltd. group and is headquartered in Ann Arbor, Michigan. For more information, visit