Wear-resistant elastomer gives seals improved run-in behavior.
WITTENSTEIN, a specialist in mechatronics and drive technology, has been conducting a decade-long analysis on the impact of seals on the reliability of industrial gearboxes.
The seals in the investigation are manufactured from a wear-resistant elastomer and are used on the drive and output ends of high-end planetary and angular gearboxes. Over a time frame of more than 10 years, WITTENSTEIN installed more than 1 million Simmerrings from Freudenberg Sealing Technologies in gearboxes.
With the help of automated evaluation and forecasting software, WITTENSTEIN engineers are analyzing the real-life failure performance of these seals. According to the company, field data on the seals’ reliability show that the number of seal-related malfunctions has declined by a factor of 10 compared to traditional seals composed of a standard material.  Since that point, the proportion of malfunctions due to leakage has been 0.025 percent, and a large share of these malfunctions can be attributed to premature failures rather than wear.
WITTENSTEIN and Freudenberg Sealing Technologies jointly developed the new seals as part of a technological partnership. The Simmerrings were manufactured from the elastomer material 75 FKM 170055, which has a high wear resistance—an especially advantageous trait for run-in behavior. This is because seals made of the standard FKM material tend to increase friction and wear under high dynamic stresses and can entrench themselves even in hardened counter-surfaces.
This in turn leads to leakage in the event of axial perturbing movements. On the other hand, the characteristics of the 75 FKM 170055 material allows the seal lip’s contact pressure to be less and the lip to be narrower, greatly reducing wear.
“Users of our high-end gearboxes expect high reliability, especially in their seals,” said Michael Schmidt, an expert in sealing technology at WITTENSTEIN.
Reliable sealing is especially important for applications in the food sector. Low-backlash planetary gearboxes are frequently used in these cases because they fulfill high requirements for precision and dynamic characteristics particularly well.
(Image courtesy of Freudenberg Sealing Technologies.)
The motion sequences for creasing and closing milk cartons, for example, must be adjusted precisely to the filling process. The packaging must also be precisely positioned and not oscillate during individual stops. Fluids must not spill over during further transport. This must all take place under strict hygienic conditions at very high speeds. There is also the fact that only certain food-grade lubricants that contain only limited amounts of additives are permitted in these applications.
“We are now taking advantage of our experience based on the field use of radial shaft seal rings – documented with the evaluation and forecasting software – to jointly develop special applications with WITTENSTEIN,” said Erich Prem, product developer for industrial applications at Freudenberg Sealing Technologies.
It is not just the productivity requirements that increase with the increasingly complex and technically demanding applications – but also the reliability of individual components. With other industries in mind, the partners are currently developing wear-resistant sealing solutions with substantially longer operating lives for gearboxes, many fewer disruptions and much reduced downtime.
For more information, visit the websites for WITTENSTEIN and Freudenberg Sealing Technologies.