One of the main development targets in the wind turbine sector is to keep turbines running for several decades, if possible without a single interruption for servicing. This demands a lot of those companies that manufacture assemblies for the powertrain and in particular those that manufacture seals, which are incredibly important elements in wind turbines because they are exposed to extreme loads and have to ensure that transmissions and generators function reliably over very long periods. In order to meet these targets, Freudenberg Simrit has refined the technology behind PTFE-impregnated nonwovens.

A key feature of its new protection seal is the sealing lip, which is made of a PTFE-impregnated nonwoven. This material is made of plastic fibers that are highly resistant to chemicals and heat. A patented process is used to impregnate the fibers with PTFE and to laminate them. The result is a nonwoven with outstanding mechanical performance characteristics.

When used in a sealing lip, the cleverly combined properties of high-performance fibers and PTFE impregnation made possible by this special production procedure mean that these nonwovens can tackle a problem that was previously almost impossible to solve: extreme sliding speeds and long service lives are now no longer mutually exclusive. What's more, the costly processing of the shaft surface is also a thing of the past.

Whereas classic seals require a ground and, where possible, hardened shaft surface, this nonwoven has a very low coefficient of friction and excellent dry running properties even at high speeds. Recent tests have shown that in individual cases, it can even be used on a varnished shaft.

Depending on the application requirements, the nonwoven can be used either directly as an individual seal (e.g. with a retaining ring) or as an additional dust lip (e.g. it can be integrated into one of Freudenberg Simrit's Radiamatic RCD labyrinth seals).

When adapted to suit an existing labyrinth or shaft seal, this protective seal does not require a special installation space. If the protection seal is used in a stand-alone capacity, it is a streamlined, cost-efficient, ready-to-fit individual seal that does not require much installation space and is easy to install.

In both versions, the innovative sealing lip material offers excellent protection against brake dust, drift sand, salt crystals, and abrasive particles in the air, as well as against splash water and spray paint.

All of this ensures that valuable main transmissions or expensive generators are protected effectively both during assembly and in tough day-to-day operation. The good chemical and thermal resistance of the material prevents the element from aging, while at the same time, the permeability of the nonwoven prevents an unwanted vacuum from building up inside the transmission.

An electrically conductive version of the nonwoven material is also available and is an alternative to expensive electrostatic work elements.

Nevertheless, the protection seal technology is not new on the market. It has already demonstrated the outstanding protection it can provide under the toughest of conditions in rally driving and in vehicles that have to pass through shallow water. It is now increasingly to be found in the engines of well-known German cars, where it provides protection against dust from the roads and splash water. In other words, the protection seal helps protect the components in powertrains both close to the ground and high up in the air.