The life of conventional spherical roller bearings for head, tail, drive, and tensioning pulleys on mining and quarrying conveyors is relatively short. These bearings are subject to contamination from hard particles (dirt, dust) and water penetrating housing seals and entering the bearings. This shortened life has cost the mine thousands of dollars in down time and repetitive maintenance costs.
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Avoid Conveyor Downtime with NSK Tough Bearings
Extend operating life in Mining Conveyor Pulleys by up to 10x with the NSK HI-TF tough steel bearings
Serious Bearings for Serious Applications
NSK offers reliable, predictable, and cost-effective bearing solutions to mining application
Success Story
Bearings in Mining Conveyor Pulleys
Bearings in mining conveyor pulleys endure some of the harshest conditions
30+ OEM Customers
Grit and contamination
Compromised lubrication conditions
Xm in customer Savings
High load
Tought Steel, HPS, High-capacity design
Download Bearing for Mining Brochure to learn more about NSKs offering for mining applications
Frequent Bearing Failures
Grit and Contamination
Shock and Vibratory Loads
Compromised Lubrication Conditions
High Load
Misalignment
The life expectancy of conventional spherical roller bearings for head, tail, drive, and tensioning pulleys on mining and quarrying conveyors is relatively short. These bearings are subject to contamination from hard particles (dirt, dust) and water penetrating housing seals and entering the open bearings. In the absence of a better solution, this costly replacement cycle has prevailed for many years.
Bearings in Mining Conveyor Pulleys
30+ OEM Customers
Grit and contamination
Compromised lubrication conditions
Xm in customer Savings
High load
Tought Steel, HPS, High-capacity design
Download Bearing for Mining Brochure to learn more about NSKs offering for mining applications
Grit and Contamination
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Compromised lubrication conditions
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Misalignment
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High load
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Shock and vibratory loads
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Bearings in mining conveyor pulleys endure some of the harshest conditions
Contamination is the leading cause of premature bearing failure. Severe contamination in mining and quarrying conveyor application results in frequent bearing failures costing businesses millions in repairs and downtime.
Bearing inner ring
Bearing raceway (catastrophic failure)
Contamination Failures
Bearing raceway
Bearing rollers
NSK Tough Steel solves your contamination problem!
Heat Treatment
- NSK developed carbonitriding heat treatment to extract a greater amount of fine-size carbide and carbonitride particles
- Increased compressive strength of the material is achieved compared to ordinary carburized bearings
Resilient, long life steel
Resulting Tough Steel material structure achieves both greater hardness and higher toughness through higher retained austenite levels
Retained Austenite
- A high level of retained Austenite reduces stress concentrated around the shoulders of dents preventing cracking and Flaking
- However, Austenite itself has a soft microstructure, and reduces the hardness despite increasing the toughness of the bearing material
Material Composition
In order to achieve greater hardness and higher retained austenite, a new steel was developed with specific additions of chrome and molybdenum.
Life Test: Result Under Contaminated Lubrication
In cases where lubricant particle contamination leads to raceway dents, crack formation and ultimately surface-originating flaking damage, Tough Steel reduces the concentration of stress around the shoulders of surface dents to defer damage and achieve longer service life.
Approx. life extension vs. ordinary carburized steel:
Hi-TF: 7 times, Super-TF : 10 times
Bearing: tapered roller bearing L44649/10
P/C=0.43. Oil bath, speed: 4 000min-1
Debries: hardness 870hv, size 74 to 147 Um, amount 150ppm
Test Conditions:
Life Test: Result Under Boundary Lubrication
In cases of insufficient EHL film and metal-to-metal contact, Tough Steel defers peeling damage by reducing the concentration of stress around the projections of the contact area.
Approximate life extension versus ordinary carburized steel:
Hi-TF: 4.7 times, Super-TF : 5.5 times
Pmax= 4400 MPa, Oil Bath, Ʌ= 0.3
Speed: 7800 min-1:
Test Conditions:
Super TF
Hi- TF
SUJ2
Ordinary carb. steel
Durability test: Wear and seizure resistance
In a Sawin test to measure the degree of wear and the seizure limit, Tough Steel material integrity reduces rate of wear to 1/3 and significantly increases seizure resistance.
Seizure resistance versus SUJ2 steel:
Hi-TF: 20% higher, Super-TF : 40% higher
Super TF
Hi- TF
SUJ2
Result under high temperatures
In cases of extremely high operating temperatures, Super-TF outperforms standard bearing steel with conventional high temperature specification.
Approximate life extension versus SUJ2 steel:
Super-TF : 4 times
Super TF
Hi- TF
SUJ2
Test Condition
Bearing: Deep groove ball bearing 6260
P/C = 0.71, clean oil bath
N= 3900 min-1
Test temperature: 160oC
NSK’s Hi-TF Steel (HTF) and Super-TF Steel (STF) series bearings are designed in a way that virtually eliminates the contamination problem and dramatically extends bearing service life in contaminated operating environments like mining. Utilizing the company’s Hi-TF Tough Steel™, NSK engineered a bearing with a removable seal that is dimensionally interchangeable with standard spherical roller bearings and requires no modification of shafts or housings.
How is NSK's Tough Steel different?
Vibrating Screen
Heavy contamination in a coal mining head pulley was causing bearing failures every 18 months leading to lost production and increased maintenance time. NSK Tough Steel bearings were installed and extended the bearing life to over 6 years.
Application: Overland Conveyor Head Pulley
NSK Solution: NSK Tough Steel bearings
Saved Cost: $5,050,880
Stage 1: Surface Denting
Stage 2: Crack Formation
Stage 3: Flaking Development
Stage 1:
Denting caused by foreign debris contamination
Stage 2:
Stress concentration around debris dents develop into cracks
Stress Concentration
Stage 3:
Cracks propagate under the load of each passing roller and develop into flaking
Dent
Cracks
Flaking
Identification of Failure Mechanisms
Success Story
Application
Overland Conveyor Head Pulley
Problem
Descriotion of the client
Solution offered
Descriotion of the client
Solution offered
Descriotion of the client
Case Study
Heavy contamination in a coal mining head pulley was causing bearing failures every 18 months leading to lost production and increased maintenance time.
Success Story
Mineral: Coal
Application: Head Pulley
Location: Western USA
Case Study
Heavy contamination in a coal mining head pulley was causing bearing failures every 18 months leading to lost production and increased maintenance time.
Customer documented savings
USD 5,050,880
Extended bearing life:
6 Years Plus
Background
Conditions
Abrasive particle contamination
Issues
Bearing Failure: approximately every 6 months due to contamination ingress
Downtime: lost production, increased maintenance cost
Solution
Upgrade: bearing material to NSK Hi- TF Tough Steel
Cost Savings: USD 5,050,880
Heavy contamination in a coal mining head pulley was causing bearing failures every 18 months leading to lost production and increased maintenance time.
Mineral: Coal
Application: Head Pulley
Location: Western USA
Background
Issues
Bearing Failure: approximately every 6 months due to contamination ingress
Downtime: lost production, increased maintenance cost
Abrasive particle contamination
Conditions
Upgrade: bearing material to NSK Hi- TF Tough Steel
Solution
Extended bearing life:
6 Years Plus
