Precise, reliable sealing systems and complementing lubricants for use in wind turbines
A new, innovative collaboration will result in precise reliable sealing systems and complementary lubricants for use in wind turbines. Simrit and Klüber Lubrication, two specialists within the Freudenberg Group, have brought together their expertise to offer the wind power industry the optimal combination of lubricants and seals – the Lube&Seal package.
By Ari-Pekka Holm, Head of Business Unit, Wind Energy, Klüber Lubrication, Germany
Primary synergies for lubrication and seals in a wind turbine include the essential bearings – main bearing, yaw bearings and pitch bearings – all operating under very different operating conditions and therefore posing very different requirements regarding lubrication and seals. The main bearing rotates slowly but is subject to a high and continuously changing load and vibration. Pitch and yaw bearings are subject to high loads as well, but they also perform an oscillating motion under strong vibration.
The lubricant must meet several requirements: it should not only form a separating film in the bearing but also at the sealing lip in order to reduce damage to the friction bodies – bodies which may consist of a variety of materials. Lubricants play a vital role in ensuring that the components conform to the required operating times. Standard lubricants are often unable to keep up with the permanently increasing performance requirements. Bearing greases, for example, should be reliable/consistent to pump and so allow precise metering in centralised lubricating systems, thereby attaining a good grease distribution. Good wear protection even under vibration increases the bearings’ lifetime during periods of idleness, false brinelling is always a major cause for concern. Also, when the power station runs at low speed, wear is provoked due to the lack of a sufficient hydrodynamic lubricant film. A good lubricant must contain suitable additives to counteract these effects. Finally, it has to be ensured that the lubricant is compatible with the elastomers involved and covers the entire operating temperature range of a turbine (–40°C to +60°C).
The technical requirements for the seal are clearly defined: it is expected to ensure tightness reliably for a long time, even while subject to severe physical, tribological and chemical stress. Seals must be designed with special wear-resistant materials for large bearings and rotary assemblies. The form-pressed seals can cover diameters up to 3,000 mm and are distinguished by their high sealing function thanks to integrated tension springs.
A critical factor for the durability of a seal is the reaction of the sealing material to the lubricant used, however, this has often received little attention in the design phase. To reduce friction and wear to a minimum, and maximise component life, the seal and the lubricant must form a functional unit. Lube&Seal offers the first opportunity to use an accurately tuned and tested seal-lubricant system.
Tested Comprehensive Solution Offers High Reliability
Once a particular combination of seal and lubricant has been developed, it is tested in the lab or in components provided by the manufacturer. These tests include standard tests as well as dynamic tests specifically designed for the expected operating conditions (especially time and temperature). 240 h DIN tests, low-temperature tests, low-temperature torque tests, friction or temperature measurements can be performed directly at the seal lip. Of course the duration of long-term tests depends on the requirements in practice, and lubricant condition analyses are also made.
All this ensures that the solution that is eventually chosen offers the user a maximum of reliability and durability. Since this approach looks at the system as a whole, development times are reduced, which in turn results in a competitive edge for the manufacturer. Due to their systematic development, these solutions enable much more accurate estimates for warranties.
Conclusion
All in all, we feel that Lube&Seal can offer better reliability due to longer equipment life, less failure, and a higher quality for the manufacturer. An additional, but equally important advantage for the wind operator and OEM is that we are now talking of a complete system – lubrication and seal, rather than individual, and separate, components.{/access}
A new, innovative collaboration will result in precise reliable sealing systems and complementary lubricants for use in wind turbines. Simrit and Klüber Lubrication, two specialists within the Freudenberg Group, have brought together their expertise to offer the wind power industry the optimal combination of lubricants and seals – the Lube&Seal package.By Ari-Pekka Holm, Head of Business Unit, Wind Energy, Klüber Lubrication, Germany
{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}Experience has shown that lubricants can dramatically influence the elastomer and sealing lip. The extreme requirements put upon equipment components are not easily met as the two separate worlds of lubrication and elastomers collide. Still, both lubricants and elastomers are only regarded as C components by purchasers and designers. The reliable function of this tribo-system, however, is a vital factor in the overall performance and service life of the combination as a whole: these C components of the tribological system have, in fact, an A function!
SynergiesPrimary synergies for lubrication and seals in a wind turbine include the essential bearings – main bearing, yaw bearings and pitch bearings – all operating under very different operating conditions and therefore posing very different requirements regarding lubrication and seals. The main bearing rotates slowly but is subject to a high and continuously changing load and vibration. Pitch and yaw bearings are subject to high loads as well, but they also perform an oscillating motion under strong vibration.
The lubricant must meet several requirements: it should not only form a separating film in the bearing but also at the sealing lip in order to reduce damage to the friction bodies – bodies which may consist of a variety of materials. Lubricants play a vital role in ensuring that the components conform to the required operating times. Standard lubricants are often unable to keep up with the permanently increasing performance requirements. Bearing greases, for example, should be reliable/consistent to pump and so allow precise metering in centralised lubricating systems, thereby attaining a good grease distribution. Good wear protection even under vibration increases the bearings’ lifetime during periods of idleness, false brinelling is always a major cause for concern. Also, when the power station runs at low speed, wear is provoked due to the lack of a sufficient hydrodynamic lubricant film. A good lubricant must contain suitable additives to counteract these effects. Finally, it has to be ensured that the lubricant is compatible with the elastomers involved and covers the entire operating temperature range of a turbine (–40°C to +60°C).
The technical requirements for the seal are clearly defined: it is expected to ensure tightness reliably for a long time, even while subject to severe physical, tribological and chemical stress. Seals must be designed with special wear-resistant materials for large bearings and rotary assemblies. The form-pressed seals can cover diameters up to 3,000 mm and are distinguished by their high sealing function thanks to integrated tension springs.
A critical factor for the durability of a seal is the reaction of the sealing material to the lubricant used, however, this has often received little attention in the design phase. To reduce friction and wear to a minimum, and maximise component life, the seal and the lubricant must form a functional unit. Lube&Seal offers the first opportunity to use an accurately tuned and tested seal-lubricant system.
Tested Comprehensive Solution Offers High Reliability
Once a particular combination of seal and lubricant has been developed, it is tested in the lab or in components provided by the manufacturer. These tests include standard tests as well as dynamic tests specifically designed for the expected operating conditions (especially time and temperature). 240 h DIN tests, low-temperature tests, low-temperature torque tests, friction or temperature measurements can be performed directly at the seal lip. Of course the duration of long-term tests depends on the requirements in practice, and lubricant condition analyses are also made.
All this ensures that the solution that is eventually chosen offers the user a maximum of reliability and durability. Since this approach looks at the system as a whole, development times are reduced, which in turn results in a competitive edge for the manufacturer. Due to their systematic development, these solutions enable much more accurate estimates for warranties.
Conclusion
All in all, we feel that Lube&Seal can offer better reliability due to longer equipment life, less failure, and a higher quality for the manufacturer. An additional, but equally important advantage for the wind operator and OEM is that we are now talking of a complete system – lubrication and seal, rather than individual, and separate, components.{/access}
