Roller seals are generally non-contact seal, that a labyrinth, an axial labyrinth seal the best, non-metallic roller price, resistance is also small. Some radial labyrinth, non-metallic roller, and some use double sets of rollers, better, non-metallic roller mill, but more cumbersome. Idler model selection the following factors: the size and characteristics of the load, the working width and speed of the conveyor belt system, conditions of use, the conveyor, the nature of the material sent predetermined bearing life, maintenance system, etc., in ensuring the strength Under the premise of weight rollers as small as possible. Assembly and welding of roller: assembly Huan idler rollers then determines the quality of the manufacturing process roller which is the most important of a process, which determines the relative position of the rollers of the parts, coaxial roller bearings error, roller shaft and the roller tube concentricity error, the finished roller runout parameters embodied in this procedure in.