A Polish steelmaker is saving nearly 3 million euros per year after switching to Germany-based NSK’s KVS four-row tapered roller bearings at one of its roll mill. With the decision proving to be so effective, the company is now adopting this solution for all of its tandem cold mills.

The steel mill started production in the 1970s, and after many successful years of operation, the management team decided that a refurbishment was necessary. To help reduce costs, the mill consulted with a local technical university on the potential for changing the original mill bearings from oil mist to oil bath lubrication.

However, switching to oil bath lubricated bearings did not result in the expected improvements, so the mill then turned to NSK (www.nsk.com) and its Added Value Programme AIP. Specialist NSK engineers then reviewed the mill design and proposed the adoption of sealed-clean KVS bearings with grease lubrication.

Four-row, tapered roller bearings were duly installed and, after one year of operation, were still providing excellent performance and productivity. As a result, the customer adopted these bearings for all of its tandem cold mills, where they are now delivering superior operating life and reduced maintenance costs compared with the previous solution.

NSK KVS bearings offer two- to four-times longer life than standard bearings as they have a special type of bore seal which averts the build-up of negative pressure that can cause the entry of water through the main seals.

Other design attributes include a special helical groove that prevents creeping on the roll neck shaft, while innovative internal bearing geometry and a special seal help provide higher load capacity.

Pre-lubricated with the recently developed AQGRD water-resistant grease, KVS bearings are available in different material specifications and in open or sealed designs.

At the Polish steel mill, thanks to the reduction in the number of bearings required, plus less downtime, fewer service hour requirements and the elimination of lubricating oil, the mill is currently saving an estimated 2,997,568 euros per annum.