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An international steel manufacturer was experiencing bearing failures on a rotary coal valve in their ore preparation plant. Failures were occuring twice per year resulting in significant lost production costs and damage to associated components. An application review identifying the current bearing design was inadequate for the applications high temperatures. NSK recommended a customized HLT bearing insert within a Self-Lube cast iron FC housing and a special heat isolating spacer. Testing of the NSK recommendation was conducted with NSK Applications Engineers overseeing the correct fitting of the bearing units within the application. The NSK bearings ran for over 12 months with no bearing failure resulting in a large overall cost saving.

Key Facts

  • Rotary Coal Valve
  • High temperature application resulting in overheating of bearings
  • Incorrect lubrication amounts and frequencies
  • NSK Solution: HLT bearing inserts with a Self-Lube cast iron FC housing, with NSK custom designed adaptor plate
  • Additional heat resisting material ring
  • Downtime avoided
  • Rotary Valve
  • HLT Self-Lube bearing insert

Value Proposals

  • NSK engineering conducted an Application Review including a Temperature Survey and a Bearing Condition Report
  • NSK engineers recommended HLT bearing inserts with a Self-Lube lube cast iron FC housing, with NSK csutom designed adaptor plate and additional heat resistant material ring.
  • Suggested changes in the lubrication amount and intervals
  • Bearings were tested, with NSK Engineering overseeing the installation and implementation of NSK recommendations
  • Reduced maintenance and lost production costs resulted in significant cost savings

Product Features

  • Special internal geometry; C5 internal clearance
  • High performance Klueber grease
  • Durable silicone rubber seals
  • Steel cage material
  • Interchangeable with standard Self-Lube® inserts
  • High performance grease and effective lubrication at extreme temperatures, with upper and lower limits of –40°C/F and +180°C/356°F
  • Efficient sealing and protection at extreme temperatures (–40°C/F and +180°C/356°F)
  • Steel cage and special internal features designed for use in high temperatures. Increase radial clearance (C5) between balls and raceways to help prevent radial preload

Cost Saving Breakdown

Before Cost p.a. NSK Solution Cost p.a.
Replacement costs x 2 times per year $135 Replacement cost once a year $68
$95/hr x 7 hours per breakdown for 2 engineers x 2 times per year $1330 $95/hr x 7 hours fitting for 2 engineers once a year $665
$9,581/hr x 7 hours per breakdown x 2 times per year $134,134 Downtime eliminated € 0
$2,738 per month for shutdown to relubricate $32,856 $1,051 per month for shutdown to re-lubricate $12,612
Total Costs $168,449 $13,345



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