Bearings for Steel & Metallurgy

Typical duty

• Very high radial load from rolling force, often with a heavy axial component.
• Working temperature from 60 to over 200 degrees C on the roll neck.
• Cooling water and mill scale washing the lubricant out of the bearing.
• Shock load at the bite, and reversing duty on reversing mills.
• Very long campaigns, with bearing life measured in months of continuous operation.

Installation & maintenance notes

• Water and scale ingress is the dominant failure cause - seal design and the lubrication system matter more than rating.
• Allow for thermal expansion between the roll neck and housing with a floating position.
• Specify the bearing for the mill's actual temperature, not the ambient figure.
• Use oil-mist or circulating-oil lubrication where the operating temperature demands it.
• Inspect roll neck surfaces and re-condition them; damaged necks destroy new bearings quickly.

Common mistakes in this industry

• Using a standard spherical roller bearing on a hot roll neck and finding it preloaded once it warms through.
• Letting cooling water into the bearing housing because the seal glands are worn.
• Setting four-row tapered clearance by feel rather than according to the manufacturer's measured procedure.

Further reading

• Temperature Effects on Bearing Fit, Clearance and Life
• Oil Lubrication Systems: Bath, Circulation, Jet and Mist
• Roller Bearing Internal Geometry: Ribs, Flanges and Guideways