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Introduction

An Spanish Steel Mill Company was experiencing bearing life times much shorter than desired. The unexpected failure of the bearings caused production stoppages, causing lost time and money. NSK Technical Department together with the Steel Mill Technical Office analyzed the working conditions of the bearings as well as the lubrication regime. As a result of these analyses, several modifications were made such as review of the fitting, suitability of the lubricants as well as the use of HPS spherical roller bearings. With all the applied changes, the running life of the bearings was greatly extended.

Hot Mill
  • Hot Mill
NSKHPS Spherical Roller Bearings
  • NSKHPS Spherical Roller Bearings

Key Facts

  • Hot Mill Application suffering unexpected failures and high production costs.
  • Technical Root Cause Failure Analysis completed to identify the causes of failure.
  • Review of the fitting process and tolerances, supporting Maintenance Departments requests for the process improvement.
  • Review of lubrication regime to optimise running conditions and prolong life.
  • Assembly NSK HPS Spherical Roller Bearings with higher Radial Internal Clearance.

Value Proposals

  • During four years the customer experienced unexpected failure in the Hot Mill
  • NSK review all applications and define the root causes of the failure
  • High temperature originated from incorrect fitting and grease lubrication failure as a result of higher productivity requirements ( Higher Speeds)
  • Bearing failures were avoided after NSK´s recommendations were applied
  • Bearing demand was reduced, from 100 to 20 per year
  • Large cost savings were obtained from reduced maintenance and lost production costs

Product Features

  • Temperature stability: up to 200° C
  • Up to twice the operating life
  • Up to 20% higher limiting speed
  • Dynamic load rating: 25% higher
  • Lower maintenance cost and improved productivity
Cost Saving Breakdown
Before Cost p.a. NSK Solution Cost p.a.
Bearing Costs 25 400 € Bearing Costs 5 080 €
Engineering Costs 1 880 € Engineering Costs 376 €
Costs of lost production 60 000 € Costs of lost production 12 000 €
Lubrication Costs 60 € Lubrication Costs 81 €
Total Costs 87 340 € 17 537 €

Reference:SS-E-7-583