ironing board cover and pad_table top ironing board cover

Requirements of the shaft
Even more important than a correct interference fit of the Oil Seal is a perfectly smooth shaft in the region of the seal, particularly if shaft surface speed is high and the medium to be sealed is under a certain amount of excess pressure. The surface roughness of the shaft depends on the average profile depth Ra of the tool marks caused by the machining process. Oil Seals made of PTFE require, independent of the surface speed, a surface roughness of between 0,1 to 0,2 mm, because PTFE has less wear resistance than rubber seals. For normal circumstances, the shaft in the region of the seal must have a surface roughness of approximately:  To summarize, the surface of the shaft in the region of the seal should not have noticeable machining marks. For pivoting shafts and other difficult or critical sealing applications, it is recommended that Oil Seals with a helical groove hydrodynamic pattern, which has a pumping effect, be used. When grinding and polishing, an axial movement of the grindstone along the shaft must be avoided in order to prevent machine lay. 

The other way oil seals work is by stopping outboard materials that can damage the machine or contaminate its lubricant. The outboard materials that the oil seal will need to stop depend on the application. However, the most common kinds are dirt, moisture, and the particles produced during manufacturing.