Dirt Stays Outside - Lubricant Stays Inside

The examined seals are made of a wear-resistant elastomer and are used on the drive and output side of high-end planetary and angular gears. There they ensure that no lubricant escapes from the gear unit and that no dirt or product residues can penetrate the gear unit. Over a period of more than ten years, Wittenstein has installed over a million high-performance Simmerrings from Freudenberg Sealing Technologies in these gearboxes. With the help of automated evaluation and forecasting software, the engineers at Wittenstein analyze the real failure behavior.

The field data on the reliability of the seals clearly show that the number of seal-related failures has decreased by a factor of ten compared to the seals used previously made from a standard material. Since then, the proportion of failures due to leakage has been only 0.025%, a large part of which is due to early failures and therefore not to wear. The new seals were developed together in a technology partnership between Wittenstein and Freudenberg.

The Simmerrings are made of the elastomer material 75 FKM 170055, which has good wear resistance. The material behaves good-naturedly when running in. Because seals made from a standard FKM material tend to increase friction and wear under high dynamic loads and can also dig into hardened mating surfaces. This can lead to leakage in the event of axial interference. The properties of the 75 FKM 170055 material allow the contact pressure of the sealing lip to be reduced and the lip to be made narrower, which significantly reduces wear.

Sealing in the food sector

Reliable sealing is particularly important for applications in the food sector. The low backlash planetary gears are often used here because they meet the high demands on precision and dynamics particularly well. The movement sequences when folding and closing milk cartons, for example, must be precisely coordinated with the filling. In addition, the packaging must be positioned exactly and must not swing back during individual stops. Liquids must not spill over during further transport. All of this should take place under strict hygienic conditions and at a very high speed. In addition, these applications only allow certain food-grade lubricants that contain only a limited amount of additives.The premium Simmerrings from Freudenberg Sealing Technologies also guarantee significantly less wear than standard FKM seals and thus significantly increase the service life.

Basis for special applications

"We are now using the experience from the field use of radial shaft seals, documented with the evaluation and forecasting software, to develop new special applications together with Wittenstein," reports Erich Prem, product developer for industrial applications at Freudenberg Sealing Technologies. Because with the increasingly complex and technically demanding applications, not only the demands on productivity increase, but also on the reliability of the individual components. The two partners are currently developing wear-resistant sealing solutions for other industries with significantly longer service life for the gearbox and significantly fewer malfunctions and less downtime. (br)