Shaft Material

Seals perform best on a medium carbon steel or stainless steel shaft. Heat treating or nitriding is especially recommended. Hard plated surfaces such as chrome-plate or nickel can also be used satisfactorily if the surface finishes are proper. Soft metal shafts are not recommended for dynamic applications.

Bore Material

Steel and cast iron provide a good surface for both rubber and metal O.D. seals. For soft alloy housings, seals with rubber O.D. provide a better sealing capacity. (The rubber covered O.D. will provide a rate of thermal expansion greater than that of the carbon steel cans, thereby helping to ensure a positive press-fit through elevated temperatures.)

Shaft Surface Finish

To optimize seal life, a minimum surface finish of 10 to 20 Ra is required in the area of lip contact. No rifling marks or helical machine leads are permitted.

Bore Finish

The housing roughness varies depending on whether you are using a rubber O.D. or metal O.D. For rubber O.D.’s 100-200 Ra, and Metal O.D.’s should be less than 100 Ra.

Shaft Hardness

In the area where the sealing lip contacts the shaft, a minimum hardness of 45 HRc is recommended. Where lubrication is doubtful, use a minimum of 55 HRc.

Bore Hardness

There is no recommended hardness for the bore, however, if the seal O.D. will be harder than the bore, i.e. plastics, a rubber O.D. seal should be used.

Shaft Chamfer

A shaft lead in chamfer of 15 – 30 degrees is recommended.

Bore Chamfer

A bore lead in chamfer of 15 – 30 degrees is recommended.

Other factors may influence how your gland design may work in your application. For more information, contact an R.E. Purvis & Associates, Inc. representative at (952) 829-5532.