Cracks in Wind Turbine Gearboxes: Engineers Found a Solution for Expensive Repairs

Introduction to the WEC Problem

White Etching Cracks (WEC) in bearing steels have long been a concern for wind energy specialists. These microstructural changes, observable under a microscope, signal costly gearbox repairs. The team of Mobil engineers decided to thoroughly investigate the WEC phenomenon and devise an effective solution. Thanks to precisely controlled changes in the composition of lubricant formulas, based on intensive research, a product was developed that gained recognition in the wind energy industry.

WEC Phenomenon Under the Microscope

WEC presents as white, etched areas in bearing steels. These changes are early warnings of impending cracks and gearbox repairs. WEC originates from subsurface stresses caused by contact fatigue, where hydrogen plays a key role. Przemysław Szczepaniak from ExxonMobil explains that understanding molecular-level interactions between lubricant additives and bearing materials is crucial for addressing the WEC issue.

The Role of Lubricant Additives

The Mobil engineering team identified tribochemical processes contributing to WEC formation. Research on lubricant additives, such as ZDDP (zinc dialkyldithiophosphate), revealed their potential impact on hydrogen penetration, which can destabilize the tribofilm layer. Through advanced formulations, the team succeeded in stabilizing this layer and minimizing the risk of hydrogen permeating the bearing steel.

Modern Lubricating Oils

The outcome of their work is Mobil SHC™ Gear 320 WT, an oil designed to protect wind turbine gearboxes. Laboratory tests confirmed its effectiveness in mitigating WEC. Implementing this oil on wind farms has led to reduced WEC incidents, increased gearbox efficiency and durability, and extended service intervals.

10-Year Warranty

Mobil SHC™ Gear 320 WT has received positive feedback from wind farms worldwide. Thanks to the durability and quality of this oil, ExxonMobil has extended the warranty period from seven to ten years. The extended warranty covers the lubricant and key gearbox components.

Ongoing Research and Development

Mobil’s research projects aim to further understand and mitigate the WEC phenomenon. Engineers are working on new generations of synthetic base oils and additive technology. Their efforts enhance practices in the wind power industry, reducing the risk of turbine gearbox failures. Find more information about WEC and Mobil oils for wind turbines here. Have additional questions? Contact us.