In late 2019, employees from the Lead Center Fluid Power (Schwalmstadt) and Oil Seals Industry (Weinheim), units of Freudenberg Sealing Technologies (FST), along with sister company Klüber Lubrication (Munich) traveled to Universal Robots in Denmark. The customer was looking for a sealing solution for its cobots. The new seal was supposed to protect the system from dirt, dust, and spraying water, and offer low friction.
Cobots are collaborative robots. They work alongside people and are not housed in an enclosed space, which exposes them to significant environmental effects. “Until now, Universal Robots used PTFE seals, but they offered too little protection against dirt, dust and spraying water,” said Engineer Steve Cowell of the Lead Center Fluid Power. The first polyurethane u-rings, which Freudenberg Xpress produced, did not satisfy the customer. “The frictional torque was too high,” Cowell said. “Then we developed a new design with a z-shaped profile.” The team reduced the size of the seal lip and put in a second groove, which made it possible to cut contact pressure and friction.
“Universal Robots was thrilled with the new design. Even the frictional torque was better, but the amount of wear was still too high,” recalled Alexander May, Design Engineer at the Lead Center Fluid Power. The team coated the seal with a lubricating lacquer to solve the abrasion problem. “That allowed us to cut the frictional torque in half again and extend the seal’s operating life.” In the meantime, Universal Robots redesigned the joint on its cobots. That meant the team had to start all over again, but it benefited from the knowledge that it had gained with the first solution. “We changed the design from exterior to interior sealing, and used the lubricating lacquer and the flexible lip again,” May said. The seal proved successful in the first tests.
The team presented the new seal in Denmark in June 2022. “Universal Robots wanted more changes, in one case involving a bead on the exterior to improve the stability of the seal,” May said. The company also changed the installation space to adapt it to the FST seal. “The customer is very satisfied and wants to head into injection-molded production. It has ordered three different dimensions for its new UR20 robot. Problem solved, and a new customer gained,” Cowell said.
