Careful specification and regular quality inspections are recommended if SSID tube is to be used. In certain circumstances however, SSID finishes, just like its rougher finish relative DOM tube, can lead to premature wear of the seal through flow erosion.
Special Smooth Inside Diameter (SSID) DOM: With the advent of improved manufacturing processes, SSID tubing is more commonplace than it was years ago.Drawn Over Mandrel (DOM) tubing as produced, can be either adequate or inadequate depending on the actual surface texture achieved and the application.The typical methods of achieving bore finishes are summarized in the figure below and bulleted details: Bore surface finishes can be more problematic. The optimum surface finish may also depend on the seal material. This gives an excellent tribological surface, and provided the rods are produced by an established supplier within a surface finish range of 0.1 to 0.3 μm Ra (4-12 μin Ra), no major problem should ensue. The hardness target should be at least 67 Rockwell C (900 HV/10). Piston rods are generally hard chrome plated. Though the surface finish requirements are not as severe, it is critical to ensure surface finish recommendations are met to maximise seal performance and life. The static sealing and housing surface also has a significant influence on the operation and service life of a seal. Proper surface finish is critical in assuring maximum seal performance and life within a given application. If the surface is too coarse, premature seal failure may occur due to the roughness of the surface, hence causing small cuts or scores in the sealing lip. If the surface is too smooth, it will not properly retain lubrication and will cause excessive seal wear due to frictional heat.
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