WEINHEIM, Germany, Nov. 14, 2023 /PRNewswire/ -- Flexible and wear-resistant with minimal frictional losses for the versatile robotic arms of cobots – that was the challenge presented to Freudenberg Sealing Technologies that became the driver for a complete redesign and development of a new seal.

It began when a manufacturer came to Freudenberg Sealing Technologies looking for a new sealing solution to reliably protect its cobots' joints from dust, spraying water and other contamination over the long haul.

Up until this point, simple PTFE rings had been used so that efficiency, energy consumption and the robotic arms' speed of motion were not overly compromised. However, the rings were not able to guarantee the required IP54 protection class. High travel speeds and the forces generated in the robot arm create an environment with temperatures as high as 60° C (140 °F). A seal not only has to withstand these temperatures long-term but extremely low material elongation is important as well to guarantee functionality in each operating mode and at all temperatures.

Due to its outstanding reputation and development expertise, the manufacturer turned to Freudenberg for a solution. As a first step, Freudenberg's experts presented a u-ring made of polyurethane (PU). But in practical tests, the frictional forces proved to be too great due to its relatively large surface. Those forces were not supposed to exceed 1 newton meter. This extremely low value made it necessary to significantly reduce the radial forces and the contact stresses on the dynamic seal lip.

A New Development Meeting Stringent Requirements

For the next step, the sealing experts changed the overall geometry to a z-profile and integrated a second groove. This greatly reduced the contact pressure and met the requirement for a frictional force of less than 1 newton meter. In the practical test, however, the level of wear was still far too high. This was mainly due to the cobots' lightweight, largely aluminum construction. The surface of the material is relatively rough due to the methods used during its processing and its basic characteristics. As a solution, Freudenberg developed a three-component solid film lubricant coating with high carbon content. The coating made it possible to further reduce the amount of wear.

SOURCE Freudenberg Sealing Technologies