NSK’s long life EP steel saves €38,400 on Sendzimir steel mill 15 May 2012

NSK's extra long life EP steel is apparently saving an unnamed operator of a Sendzimir mill €38,400 annually, by overcoming a problem of inner ring wear on mill bearings.

The Sendzimir mill, used for cold-rolling wide sheets of metal to close tolerances, has small-diameter working rolls, each backed by a pair of supporting rolls, with each pair supported by a cluster of three rolls.

NSK says that it was in the operation of these rollers that the bearing wear and premature failures were occurring – with bearing life reduced to 1,500—3,000 hours.

Operating conditions evidently meant that the inner raceways of the bearing rings were flaking, reducing the life of the roller support bearings considerably.

Failures were costing the mill operator €61,800 annually, made up of: new bearings at €42,000; six maintenance stops per year, each of three hours, at €1,000 per hour; and €1,800 associated costs.

NSK became involved through its asset improvement programme. Engineers from NSK were invited to view the mill, and recommended assembling new bearings, with the inners rings manufactured from NSK's special EP steel, which offers up to three times the life of conventional bearing materials.

NSK explains that EP steel offers significant improvements in purity and reduction of non-metallic inclusions. It also has fewer large particles than vacuum arc remelted (VAR) steel or conventionally refined steels.

Previously, bearings were lasting an average of two months. However, with the new equipment fitted, bearing life has increased by more than 5,000 hours.

Brian Tinham

Related Companies
NSK Bearings Europe Ltd

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