LONG-LIFE SUPER-TF SPHERICAL ROLLER BEARINGS
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LONG-LIFE SUPER-TF SPHERICAL ROLLER BEARINGS FOR WIND TURBINE MAIN SHAFTS STAY IN MOTION. STAY IN CONTROL.

SUSTAINABLE SOLUTIONS ROLLING BEARINGS FOR WIND ENERGY Modern turbines are immense structures, typically weighing over 200 tons with each rotor blade spanning 120 feet or more. Operating in high and frequently changing winds, the mass of these systems, the staggering kinetic forces, and the uniquely challenging operating conditions place significant demands on a wind turbine’s components - particularly the bearings. Reliability is essential. With remote and restricted access onshore and offshore, service and maintenance on these machines are complex and costly and scheduled sparingly – with...

LONG-LIFE RELIABILITY: SUPER-TF BEARINGS Wind turbine main shaft bearings work under immense and continuous dynamic wind loads while rotating at ultra-low speeds, a fraction of those at which they typically operate. The interaction of these conditions and the resulting mechanical stress on power train components presents challenges to bearings for wind turbine main shafts that can result in excessive wear and unattainable requisite life requirements. That is, for conventional bearing solutions. NSK’s Super-TF (STF) spherical roller bearings for main shafts are anything but conventional....

DESIGN AND OPERATING ADVANTAGES Super-TF (STF) series bearings are designed to deliver outstanding durability in operating environments subject to contamination, or conditions that instigate severe wear. Utilizing advanced material engineering and heat treatment technology, they provide the longest bearing life for the wind turbine industry. Long-life Super-TF steel inner and outer rings High-capacity internal design Controlled raceway surface finish Diamond-like wear resistant coating (DLC) Precision machined brass cage Lubricating groove and holes DESIGN FEATURES › Ultra-large spherical...

HIGH PERFORMANCE FACTORS 1 ADVANCED MATERIAL TECHNOLOGY › Super-TF steel promotes longer life with dramatically increased resistance to wear and seizure 2 MACHINED BRASS CAGE › Heavy-duty two-piece cage design delivers superior performance in applications subject to heavy and/or impact loading › Cage pocket geometry and finger length provide superior roller guidance and controlled roller skew › Precision-machined contours optimize lubricant flow to rolling contact surfaces 3 WEAR-RESISTANT ROLLERS › Diamond-like coating (DLC) increases roller surface toughness with extremely low friction...

HIGH PERFORMANCE FACTORS: SUPER-TF STEEL SUPER-TF (STF) MATERIAL TECHNOLOGY FAILURE MECHANISMS IN MAIN SHAFT With the expectation to operate successfully for 20 years or longer, durability is crucial for the spherical roller bearings used in wind turbine main shafts. During their operating life they must endure immense radial and axial loads while operating at ultra-low speeds. Effective lubrication of rolling Ultra-low speed contact surfaces is compromised, and rollers are prone Uneven load distribution Heavy loads to differential slip - initiating inordinate stress, wear and potential...

Life test: Result under boundary lubrication (∆=0.3) 1 Catalogue life General carburized steel Super-TF steel * tapered roller bearings Life test: Result under foreign contamination General carburized steel Super-TF steel * ball-rod rolling contact fatigue test

DEVELOPMENT OF SUPER-TF STEEL SUPER-TF LONG-LIFE STEEL Fig. 2 - Average diameter of carbide and carbonitride Average diameter of carbide and carbonitride particles, Super-TF bearing particles, Super-TF bearing r/c value r/c value number of particles or casting sand in the lubricant create dents in the rolling contact surfaces, and stress concentrated around these dents eventually leads to cracking and to surface-originating flaking. Reducing the concentration of stress around the shoulders of surface dents is directly related to achieving longer service life from the bearing. NSK research...

OPERATING CHARACTERISTICS Service life under contaminated lubrication Service life under contaminated lubrication Fig. 5 - Servicelife under contaminated lubrication Service Life Under Contaminated Lubrication Conditions Bearing service life is generally impacted by the conditions contamination in the lubricant. Under contaminated Percent failed, % % Percent failed, in which the bearing is used and by the amount of lubricated conditions, service life may fall to as little as 1/5 of the catalog life. Designed specifically to deliver longer service life in such conditions, Super-TF Bearings...

DESIGNATION SYSTEM SUPER-TF SPHERICAL ROLLER BEARINGS FOR MAIN SHAFT Special Material Bore Reference Number Dimension Series Surface Treatment Internal Design DESIGNATION Special Material Designation Cage Type Lubrication Features Internal Clearance long-life Super-TFTM steel Internal Clearance Process Control Spec. lubrication groove and holes in the outer ring custom radial clearance, in microns Surface Finish Specification wide series 240 most commonly used in main shaft applications advanced raceway surface finish to promote reduced wear Process Control Specification special process...

ACCUMULATED EXPERTISE Optimum engagement with our global technology network and design solutions. Intensive project management. Comprehensive engineering support. For main shaft, gearbox and generator applications alike, NSK deploys our accumulated expertise in collaboration with turbine builders and operators to achieve: › advanced design and material technologies for high-capacity, long-life performance › innovative solutions to negate unique phenomena such as white etching cracks (WEC) and electrical erosion › undeterred equipment performance with condition monitoring › control measures...

NSK AMERICAS United States NSK Corporation Ann Arbor MI 1.888.446.5675 Canada NSK Canada Inc. Mississauga ON 1.888.603.7667 Mexico NSK Rodamientos Mexicana, S.A. de C.V. Silao Guanajuato MX 52.472.500.9500 Brazil NSK Brasil Ltda. Sao Paulo SP 55.11.3269.4700 Argentina NSK Argentina SRL Buenos Aires 54.11.4762.6556 Latin America NSK Latin America Inc. Miami FL 1.305.477.0605 Website: www.nskamericas.com NSK Global: www.nsk.com Every care has been taken to ensure the accuracy of the data contained in this brochure, but no liability can be accepted for any loss or damage suffered through...