There is no single O-ring material suitable for every part of an industrial robot. The right choice depends on the function of the sealed component, the operating medium, temperature, pressure, and type of movement. An O-ring used in a hydraulic actuator may require different properties from one installed in a pneumatic gripper or a cooling circuit.
NBR is a common choice for industrial applications involving mineral oils, lubricating oils, and hydraulic fluids that are compatible with nitrile rubber. It offers good oil resistance, mechanical strength, and a practical balance between performance and cost. For hydraulic connections and many general-purpose sealing points, NBR is often a suitable starting material.
HNBR may be considered when the sealing point is exposed to higher temperatures, repeated mechanical movement, or more demanding aging conditions than a conventional NBR compound can comfortably handle. Its improved resistance to heat aging and mechanical stress can be useful in selected robotic actuators and transmission-related equipment. The actual performance still depends on the specific compound and operating conditions.
FKM is another option when higher temperatures or particular oils and chemicals are involved. It is commonly used in demanding industrial environments where resistance to heat and many hydrocarbon-based fluids is important. However, it should not be treated as a universal upgrade. Some fluids, including certain ketones, amines, and hot-water or steam environments, may require a different elastomer.
Other materials can be appropriate in more specialized parts of a robotic system. EPDM is worth considering for compatible water-based fluids and certain cooling applications, but it is generally unsuitable for mineral oils and petroleum-based greases. Silicone rubber offers good flexibility over a broad temperature range, especially at low temperatures, but its mechanical strength and wear resistance must be evaluated carefully in dynamic applications.
The type of movement is just as important as the material. O-rings are widely
used in static sealing and can also serve in suitable reciprocating applications
when the groove, surface finish, lubrication, and operating conditions are
properly designed. Continuous rotary movement creates different friction and
wear conditions. A conventional O-ring should not automatically replace a rotary
shaft seal in a continuously rotating joint.
Industrial robots contain many different sealing points, including hydraulic cylinders, pneumatic grippers, gear units, cooling connections, and other auxiliary systems. Each location should be evaluated separately. Engineers should confirm the fluid compatibility, temperature range, pressure, movement, groove dimensions, and required service life before choosing an O-ring compound.
A reliable material selection process starts with understanding what the seal actually does inside the robot. Matching the elastomer to the specific component and working environment is more important than choosing a material simply because it is commonly used in industrial automation.
