Cylindrical roller bearings mounted on a continuous caster were only last for 1-2 months before a major European steel mill failed.To remedy the situation, the plant invited NSK’s team of experts to review application and operating conditions, a process that culminated in the adoption of NSK’s sealed spherical roller bearings.The result: EUR 14,850 in downtime and maintenance costs saved per year.The machine produces I-beams using a series of rolls to maintain pressure on the profiles as the molten steel solidifies.Bearings mounted on the shaft support each set of rolls.In steel plants, cylindrical roller bearings are lubricated with oil through complex piping systems.Unfortunately, high maintenance costs are the norm due to the time it takes to disconnect and reconnect piping after each bearing failure.Due to the harsh nature of the application (high temperatures, contamination, high loads) – and machine design constraints that prevent the installation of heavy-duty bearings – cylindrical roller bearings have a service life of only 1-2 months. To provide improvements, NSK summarizes the analysis , proposed to install a segment of rollers with sealed spherical roller bearings (60 in total).Due to the high sealing performance of the seal, NSK’s solution doubled the maintenance interval to 2-4 lunar spherical roller bearings, resulting in significant cost savings of €14,850 (for only one part of the caster).Rather than the single lip concept of standard sealed spherical bearings, NSK’s design utilizes a special outwardly extending spring loaded lip seal made of nitrile rubber that provides strong protection from contaminants.Savings of EUR 14,850 are only related to reduced downtime and maintenance costs.In reality, however, the steelmaker is enjoying many additional savings.Another key factor, for example, is that NSK’s sealed spherical roller bearings use long-life, high-temperature grease, which eliminates oil bills.In addition, the solution is more environmentally friendly as there is no need to deal with the contaminated oil, which saves another expense.Most notably, however, no re-grease is required for the life of a sealed NSK bearing, which means the oil piping system does not need to be dismantled and reinstalled after a bearing failure, greatly reducing the time required for maintenance.Overall, the time it takes to replace the sectors is now 10 hours instead of the previous 20 hours.In terms of bearing design, NSK’s sealed spherical roller bearings feature symmetrical rollers and raceways to prevent edge load issues at the contact point under high operating conditions.In addition, the special chamfer configuration ensures smooth axial movement of the bearing at the free end.Such was the success of the steelmaker’s project, NSK received an order for 900 bearings to replace all parts of the existing cylindrical roller bearing caster, with corresponding multiplied cost savings.The standard range of NSK sealed spherical roller bearings is now available from 50 to 130 mm inner diameter (90-280 mm outer diameter).According to industry standards, the maximum allowable deviation is 0.5°, while the maximum operating temperature is 80ºC, although this can be increased depending on the seal material and grease type used.As a final note, NSK sealed spherical roller bearings have a maximum limiting speed of 8 m/s (determined by the allowable linear speed at the point of contact with the sealing lip), ensuring their suitability for other applications involving higher operating speeds continuous casting.
For further information please contact: NSK Deutschland GmbH Harkortstraße 1540880 RatingenGermany Tel: +49 2102 4811280 Email: pilath-m@nsk.com Website: https://www.nskeurope.com
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Post time: Jan-20-2022