Overcoming Nature with Technology

Harnessing natural energy demands engineered innovation to overcome the challenging forces of nature.

Operating under high and frequently changing winds and uniquely challenging operating conditions, the sheer the mass and staggering kinetic forces within wind turbine drivetrain systems place significant demands on components – particularly the bearings.

For turbine builders and operators alike, reliable and cost-effective operation requires a development partner to simulate, test, and deploy advanced product technologies that deliver the highest level of performance and efficiencies.

A partner like NSK.

Durability by Design: Long-Life Super-TF Steel

Immense and fluctuating loads. Speeds that range from extremely low in main shafts to rapid acceleration and deceleration in gearboxes. Lubrication challenges, including foreign and system generated contamination.

For conventional bearings, achieving fatigue life expectations without unexpected downtime and maintenance incidents is nearly unimaginable.

NSK’s long-life Super-TF (STF) series rolling bearings are designed to deliver outstanding durability in wind turbines. Through advanced material engineering and heat-treatment technology, Super-TF steel mitigates the damaging impact of these mechanical stresses to deliver:

White Structure Resistance: AWS-TF Steel

The unique phenomenon widely known as White Structure Flaking (WSF) or White Etching Cracks (WEC) can severely and detrimentally impact the performance life of bearings in wind turbine gearboxes. In these cases, hydrogen permeates the bearing steel and instigates subsurface degradation in the form of white structure. From the boundaries of these embrittled regions, cracks form and inevitably propagate under load stress until bearing flaking damage prevails.

With our AWS-TF steel, NSK has refined alloy chemical composition and heat-treatment technology to deliver our most advanced countermeasure to decrease the diffusion rate of hydrogen and delay this microstructural change.

Tests have shown that while bearings made with AWS-TF teel do not eliminate the risk of WEC, the delay before damage appears is seven times longer compared with onventional bearing steels.

NSK Products for Wind Turbines

Resources

Contact NSK Americas

Spherical roller bearings

For main rotor shafts 

Material options:  

• Super-TF steel
• DLC coated rollers

Double row cylindrical roller bearings, full complement

For planetary gears 

Material options:  

• Super-TF steel
• black oxide coating

Integrated outer ring bearings, tapered and cylindrical roller types

For planetary gears

Material options:  

• Super-TF steel
• black oxide coating

Single row tapered 
roller bearings

For planetary gears

Material options:  

• Super-TF steel
• black oxide coating

Single row cylindrical roller bearings, full complement

For planetary carriers

Material options:  

• Super-TF steel
• black oxide coating

Double row tapered 
roller bearings

For low-speed intermediate shafts

Material options:  

• Super-TF steel
• black oxide coating

Download the 
Extra Capacity ECA  
Spherical Roller Bearings
Brochure

Download the 
Gearbox Bearings
Brochure

NSK Americas
4200 Goss Rd
Ann Arbor, MI 48105
NSKAmericas.com
NSKAutomation.com

Harnessing natural energy demands engineered innovation to overcome the challenging forces of nature.

Operating under high and frequently changing winds and uniquely challenging operating conditions, the sheer the mass and staggering kinetic forces within wind turbine drivetrain systems place significant demands on components – particularly the bearings.

For turbine builders and operators alike, reliable and cost-effective operation requires a development partner to simulate, test, and deploy advanced product technologies that deliver the highest level of performance and efficiencies.

A partner like NSK.

Immense and fluctuating loads. Speeds that range from extremely low in main shafts to rapid acceleration and deceleration in gearboxes. Lubrication challenges, including foreign and system generated contamination.

For conventional bearings, achieving fatigue life expectations without unexpected downtime and maintenance incidents is nearly unimaginable.

NSK’s long-life Super-TF (STF) series rolling bearings are designed to deliver outstanding durability in wind turbines. Through advanced material engineering and heat-treatment technology, Super-TF steel mitigates the damaging impact of these mechanical stresses to deliver:

The unique phenomenon widely known as White Structure Flaking (WSF) or White Etching Cracks (WEC) can severely and detrimentally impact the performance life of bearings in wind turbine gearboxes. In these cases, hydrogen permeates the bearing steel and instigates subsurface degradation in the form of white structure. From the boundaries of these embrittled regions, cracks form and inevitably propagate under load stress until bearing flaking damage prevails. 

With our AWS-TF steel, NSK has refined alloy chemical composition and heat-treatment technology to deliver our most advanced countermeasure to decrease the diffusion rate of hydrogen and delay this microstructural change.

Tests have shown that while bearings made with AWS-TF steel do not eliminate the risk of WEC, the delay before damage appears is seven times longer compared with conventional bearing steels.

Spherical roller bearings

For main rotor shafts 

Material options:  

• Super-TF steel
• DLC coated rollers

Double row cylindrical roller bearings,
full complement

For planetary gears 

Material options:  

• Super-TF steel
• black oxide coating

Integrated outer ring bearings,
tapered and cylindrical roller types

For planetary gears

Material options:  

• Super-TF steel
• black oxide coating

Single row tapered roller bearings

For planetary gears

Material options:  

• Super-TF steel
• black oxide coating

Single row cylindrical roller bearings,
full complement

For planetary carriers

Material options:  

• Super-TF steel
• black oxide coating

Double row tapered roller bearings

For low-speed intermediate shafts

Material options:  

• Super-TF steel
• black oxide coating

Learn more about how NSK’s
Super-TF Tough Steel can
deliver exponentially longer
service life in wind turbine main
shaft and gearbox applications.

Watch the video >>

Life test: Result under hydrogen charged lubricant

6206 special lubrication oil test   P/C=0.46; N= 3000 min-1; Oil bath lubrication

Learn more about the
mechanisms behind White
Structure Flaking.

Watch the video >>

Coating Countermeasures

NSK: Global Solutions for a Better Future

Black Oxide Coating

Recommended by NSK as an effective surface treatment for all gearbox positions, it improves run-in behavior and counteracts bearing damage due to slippage that occurs typically during start-up. It also offers protection against corrosion and hydrogen penetration / white structure formation.

Diamond-Like Coating

By increasing surface toughness with considerable hardness, DLC mitigates roller wear and damage in main shaft bearings for an extended bearing service life.

Duplex tapered 
roller bearings

For high-speed intermediate, high-speed and low-speed intermediate shafts

Material options:  

• Super-TF steel
• AWS-TF steel
• black oxide coating

Single row cylindrical 
roller bearings

For high-speed intermediate and high-speed shafts

Material options:  

• Super-TF steel
• AWS-TF steel
• black oxide coating

Four point contact
ball bearings

For high-speed intermediate and high-speed shafts

Material options:  

• Super-TF steel
• black oxide coating

Deep groove ball bearings

For pitch motors, conduit tubes and generators

Material options:  

• ceramic rolling elements
• ceramic coating

360˚ Life Cycle Reliability

Optimal engagement with our global technology network. Intensive project management. Exhaustive engineering support. NSK leverages our accumulated expertise in collaboration with turbine builders and operators to achieve:

• Advanced design solutions for high-capacity, long-life performance
• Undeterred equipment performance with holistic monitoring and data management
• Control measures and processes - the NSK Wind Standard

With NSK as a development partner, our customers embark on a critical path to realizing the highest level of reliability.

Learn more about how NSK’s Super-TF Tough Steel can deliver exponentially longer service life in wind turbine main shaft and gearbox applications.

Watch the video >>

Watch the video >>

Learn more about the mechanisms behind White Structure Flaking.

Life test: 
Result under hydrogen charged lubricant

6206 special lubrication oil test   
P/C=0.46; N= 3000 min-1; Oil bath lubrication

Black Oxide Coating

Recommended by NSK as an effective surface treatment for all gearbox positions, it improves run-in behavior and counteracts bearing damage due to slippage that occurs typically during start-up. It also offers protection against corrosion and hydrogen penetration / white structure formation.

Diamond-Like Coating

By increasing surface toughness with considerable hardness, DLC mitigates roller wear and damage in main shaft bearings for an extended bearing service life.

Duplex tapered roller bearings

For high-speed intermediate, high-speed and low-speed intermediate shafts

Material options:  

• Super-TF steel
• AWS-TF steel
• black oxide coating

Single row cylindrical roller bearings

For high-speed intermediate and high-speed shafts

Material options:  

• Super-TF steel
• AWS-TF steel
• black oxide coating

Four point contact ball bearings

For high-speed intermediate and high-speed shafts

Material options:  

• Super-TF steel
• black oxide coating

Deep groove ball bearings

For pitch motors, conduit tubes and generators

Material options:  

• ceramic rolling elements
• ceramic coating

Download the 
Main Shaft Bearings
Brochure