A major steel producer was not satisfied with the performance of the four-row tapered roller bearings that were installed in its cold rolling mill: steel shavings from the production process were getting into the bearings and having a detrimental effect on reliability. NSK performed a detailed analysis of the bearings on site together with a failed bearing and lubrication review. This prompted a recommendation to utilise NSK’s Tough technology steels which have a far better resistance to damage caused by debris ingress.

Key Facts

  • Cold rolling mill
  • Damage of the bearings due to ingress of steel shavings from the production process
  • NSK solution: Bearings of WTF steel
  • More than 3× longer life-time
  • Reduced downtime
  • Cost savings for bearings and maintenance
  • Steel foil
  • 4-row WTF (water tough) bearing

Value Proposals

  • Analysis of the bearings, the grease, the structure and the design of the billet mill
  • NSK bearings made of WTF steel are designed for extreme operating conditions such as those involving solid and liquid contamination
  • Technical support including on site engineering consultancy and lab based bearing analysis

Product Features

  • Steel material technology
  • Special NSK heat-treatment technology
  • Optimum chemical composition design technology
  • Available for four-row cylindrical and four-row taper roller bearings
  • Bearing life is 3 times longer than that of conventional bearing
  • Reduced non-metallic inclusions on raceway surface inhibiting generation of surface cracks
  • Grain boundaries have been strengthened to help prevent the propagation of cracks

Cost Saving Breakdown

Before Cost p.a. NSK Solution Cost p.a.
Bearing Life of the previous bearings: 4 months

Lost production costs: € 1.000/h downtime × number of replacements × 4 unexpected downtimes per year

€ 44.000 Bearing Life of the new bearings: 12 months

Lost production costs: € 1.000/h downtime × number of replacements × 1 unexpected downtime per year

€ 17.600
Total Costs € 44.000 € 17.600



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