STUDY OF THE BEHAVIOR OF LIP SEALS IN PNEUMATIC ACTUATORS

The simulation of pneumatic actuators needs a knowledge of friction force under changing of the operating conditions. Friction force depends on a number of factors, including operating pressure, seal running speed on the cylinder barrel and road, barrel material and surface roughness, seal dimensions and profile, seal material, lubrication conditions, cylinder distortion during assembly, and operating temperature of actuator components. This paper shows a system for measuring the friction force caused by a lip seal used in pneumatic cylinders. Measurements are made in order to assess the influence of seal material and dimension, barrel material and surface finish, and operating conditions on friction force. Results of experimental tests show that seal friction forces for grease-lubricated service are clearly dependent on speed and pressure and are less sensitive to other parameters, i.e., barrel material and roughness, seal material, and profile. Finally a comparison among different kinds of seals is made by means of proper sensitivity coefficients.