SKF raises performance of bearings in wind turbine gearboxes

SKF has developed a new roller bearing for wind turbine gearboxes that offers bearing rating life at the forefront of the industry and enables reduction of downtime and maintenance.

The SKF high durability gearbox bearing for wind relies on a tailored combination of steel and heat treatment process that is developed to raise fatigue resistance and robustness. A thermochemical heat treatment process improves its surface and subsurface properties.

“The heat treatment process enriches the surface layer of the bearing components and improves the material strength both at and below the surface, covering the high stressed material volume during bearing operation”, says David Vaes, manager of the Wind Gearbox Competence Centre at SKF. “Rolling bearing performance very much depends on material parameters such as microstructure, residual stress and hardness.”

This tailored steel and heat treatment process has several benefits: it increases bearing rating life and enables downsizing; and increases the new bearings capacity to resists typical failure modes in gearboxes, such as premature failures related to white etching cracks (WECs), micropitting and wear.

Internal tests and calculations show up to a fivefold increase in bearing life compared to current industry standard. Moreover, an up to 10-times higher robustness against stress induced premature failures with WECs have been proven on inhouse test rigs.

The improved performance of SKF high durability gearbox bearings mean the bearings can be downsized, helping to increase torque density of the gearbox. This is critical in the latest generation of multi-megawatt turbines.