Oct. 16, 2025 – Trelleborg Sealing Solutions launches the Stefa Mini portfolio of seals optimized for the demands of next-generation robotics.
Lighter with smaller cross sections, Stefa Mini seals perform at increased speeds and accelerations while remaining highly robust and effective, making them ideal for use in machines designed for complex, accurate and fast movements.
Reflecting the increasingly challenging demands of various industries requiring smaller and lighter robots with faster acceleration, the range is targeted at robotic joints, servo and direct drive motors, gearboxes and speed reducers, and general industrial automation applications.
David Kaley, Global Segment Manager Industrial Automation, said: “With over four million robots across the globe, and the expectation that number will increase by half a million a year, the industrial automation market is thriving. Stefa Mini seals are designed specifically to excel in meeting the demands of today’s smaller, lighter robotic applications that operate at higher speeds and accelerations.
“It goes without saying they provide excellent, durable sealing, while extending maintenance intervals and cutting energy usage through reduced friction, making them more efficient in both power and cost terms. For today’s compact but complex, accurate and fast robotic applications they provide the optimal solution.”
Produced with proprietary Trelleborg fluoroelastomer (FKM) compounds for excellent chemical compatibility, the Stefa Mini range is also available incorporating food-grade stainless steel designs and in PFAS-free formulations, and comprises three seal designs.
The Stefa Mini Radial Shaft Seal’s cross-section of only 5 mm x 5 mm/0.2 inch x 0.2 inch delivers exceptional sealing performance even at high accelerations. Engineered specifically for robotic joints, servo motors and speed reducers, its unique design accommodates oscillating and bidirectional robotic motion at high acceleration, providing outstanding durability for long service life. High rotational speeds and acceleration are achieved through its low-torque design and optimal radial load. Available in diameters ranging from 10 mm to 100 mm/0.39 inch to 3.9 inch and with either a single or a double lip, it effectively seals grease and oil to prevent leakage and contamination.
The versatile and robust Stefa Mini Cassette Seal showcases a small 5 mm x 6.5 mm/0.2 inch x 0.26 inch cross-section comprising a radial shaft seal preassembled in a metal sleeve for enhanced protection against leakage and contamination. Its innovative design eliminates the need for shaft hardening and grinding and other expensive shaft surface preparation, significantly reducing the cost and time associated with seal replacement while maintaining space, weight and energy saving benefits.
The Stefa Mini Cassette Seal excels in robotic joints with grease and oil media, effectively supporting forward and reverse rotation, back-and-forth oscillations and high rotational speeds and acceleration in servo motors and speed reducers. Engineered to withstand pressure washing, it is available in diameters ranging from 25 mm to 100 mm/1 inch to 3.9 inches.
As its name suggests, the Stefa Nano Radial Shaft Seal features a very small 3mm x 3 mm/0.12 inch x 0.12 inch cross-section with a double lip, making it ideal in components with extreme space and weight limitations. With low torque, high sealing performance, enhanced durability and compatibility with grease, it effectively prevents lubrication leakage while excluding contaminants even in high-acceleration and high-speed applications. Requiring a split groove fitting for retention, Stefa Nano is ideal in robotic joints with oscillating and forward and reverse rotational movements. It is available in diameters ranging from 10 mm to 50 mm/0.39 inch to 2 inches.
In tests the Stefa Mini range proved its performance and durability over 5,000 running hours in typical application conditions, and even under extremely accelerated cycles, a significant challenge combining speed and longevity with high acceleration.
Testing was undertaken by the Trelleborg Sealing Solutions Rotary Process Development Center located in Turin, Italy. The facility brings product development, prototype production, validation testing and manufacturing together under one roof. With a focus on customer service, the facility integrates advanced simulation tools with innovative testing capabilities and places automation and efficiency at the heart of the manufacturing process.
