Uprated bearings reduce downtime in steelworks

A continuous annealing process line at a major UK steelworks was experiencing unplanned downtime of around 17 hours/year, on average, at an hourly cost of EUR21,915 - equating to EUR372.558 per year. The stoppages also meant that heavy lifting gear had to be hired, and additional maintenance personnel employed for the duration of the downtime periods.

NSK has worked with leading global steel makers to develop a package of high-performance bearings that address downtime problems in all areas of steelmaking. This experience was decisive in the company being asked to visit the steelworks, determine the problem on the annealing process line accumulator sheave, and then come up with a solution.

After analysing failed bearings on the annealing process line, NSK redesigned the assembly to accommodate a more robust bearing arrangement using crane sheave bearings. As the name implies, crane sheave bearings are usually employed in crane sheaves, in quarries, ports and building sites. However, the high load capacity and advanced levels of sealing provided by these bearings means that they also suitable for applications in the demanding conditions prevailing in steelmaking environments.

Bearing trial

An initial trial of the crane sheave bearings was undertaken on the annealing process line to determine their effectiveness. The new bearings performed successfully, providing a maintenance-free operating life that was over three times longer than that of the original bearings. On the basis of this performance, NSK has calculated an operating life of at least five years for the bearings.

An NSK spokesman commented: "We knew from previous steel industry experience that crane sheave bearings would deliver the optimum solution in this application. They are essentially full-complement cylindrical roller bearings offering an advanced sealing system that minimises grease leakage and increases resistance to the entry of water and other foreign substances. Their ability to provide reliable life in arduous environments is enhanced by machined holes, which are provided on the inner and outer rings of the bearings to allow grease replenishment, even while the bearing is in place. In addition, the bearings are supplied with a phosphate surface treatment to improve their resistance to corrosion."

Free publication

NSK has detailed its innovative bearing products for the steel industry in a new publication. Running to 40 pages the free booklet provides a wealth of information regarding the choice of bearings for plant and equipment used in steelmaking processes. Free copies are available from NSK's Marketing Department by telephoning +44 (0)500 2327464.