A steelmaker based in Poland is said to be saving nearly €3 million per year after switching to NSK’s sealed-clean KVS bearings in its roll mill, and is pleased enough with the performance of the four-row tapered roller bearings that it has now adopted them for use in all of its tandem cold mills.
The mill began production in the 1970s, and after many years of operation the management team agreed that a comprehensive refurbishment was necessary. To help reduce costs, the mill consulted with a local technical university on the potential for changing the roll mill bearings from oil mist to oil bath lubrication, on the basis that misting lubrication was seen as problematic. However, oil bath-lubricated bearings did not result in the expected improvements and the mill was left with what the management determined to be a significant issue. To try and resolve the challenge, the team at the steelmaker turned to NSK, whose specialist engineers reviewed the mill design and proposed the adoption of sealed-clean KVS bearings with grease lubrication.
The four-row, tapered roller bearings were duly installed and, after a year of operation, they were still providing excellent performance. As a result, the operator has now adopted these bearings for all of its tandem cold mills, where they are said to be delivering improved operating life and reduced maintenance costs compared with the previous solution. NSK claims that its KVS bearings offer 2–4 times the service life than standard bearings and cites a number of reasons for this. For instance, a special type of bore seal 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 interesting 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 both open and sealed designs. At the Polish steel mill, thanks to the reduction in the number of bearings required, coupled with less downtime, fewer service hour requirements and the elimination of lubricating oil (NSK KRV bearings are pre-installed with grease), the mill states that it has calculated a saving of €2,997,568 per annum.
Go to www.nskeurope.com to learn more about NSK’s sealed-clean KVS bearings.