seal runner / sleeve material

[rmetzger]

Does anyone have experience with making seal runners out of a corrosion resistant (ie stainless) steel. We were looking at 304 (mentioned by a colleague) and 420 (due to its increased hardenability).

Any material and hardness suggerstions?

 

[unclesyd]

Comeback with a little more information concerning the application, sizes, speed and enviroment that the sleeve and shaft will see.
What it the type seal and material of the seal?
How are you going to install the sleeve?

304 SS is not a good riding area for most seals.

The standard is a thin carbon steel sleeve that installs in the seal area.

 

[rmetzger]

It is a lip seal manufactured from a teflon composite, surface speeds will be around 2000 in/sec max and about 800 in/s nominal.

The sleeve will be a press fit on the shaft with an o-ring seal on the joint. the materail eneds to be corrosion resistant against high humidity and salt water contamination.

 

[unclesyd]

At your speeds I've got to do a little looking as some old standbys fall from grace at this surface speed.
This is extremely fast for a non-energized lip seal to function.

I was looking at some of the PH SS steels but I've got to check the surface response to a high speed seal. 420 would work as far as hardness and possible surface finish but I am a little concerned about the corrosion aspect.

You didn't mention the dia of the shaft. This is needed to see what's needed in a sleeve.

A little more detail will help everyone in their suggestions, me especially.

 

[rmetzger]

The shaft diameter is 13mm, the OD of the sealing surface of the ring is .750 nominal. The seal was specifically designed for this application and surface speeds but its still on the outside edge of its performance so extensive testing will be completed. The sealed fluid is a aviation oil and will serve a role to transfer heat from the seal runner to help cooling and the running time will normally be fairly small (minutes) so that part of the equation may not have as high of importance as wear and corrosion.

420 seems to have the required hardness but, like you, I'm a bit concerned with its corrosion resistance. The research I've done points to acceptable properties in the environment if proper heat treatment and surface finishes are applied to the part (which should not be a problem). The machining characteristics of the material has me a bit concerned as well as one of the rings will need an internal o-ring/seal groove.

 

[sreid]

As previously mentioned in other forums, Kolsterising might be just the ticket for your application.

http://www.kolsterising.bodycote.com/

 

[unclesyd]

Your statement about intermittent service is kicker when salt water is involved. This gives one nightmares if you have a crevice.

As posted by sreid liquid nitriding is very good option.


420 SS can be ground and polished to a fine finish, < 8 RMA, needed for your application. I see your concern for machining a internal miniature O-ring grove. This could be facilitated by the use of 420 FM. I have no experience in nitriding the 420 FM material. Both materials also requires a high temperature heat treatment.

I would trend toward liquid nitrided 17/4 PH SS using the QPQ (Quench Polish Quench) process. The PH alloys use a low temperature heat treatment.

I have also used 22-13-5 for shafting if there is idle time in the presence of salt water. The only problem is that I haven’t nitrided any of it.

One other standalone alloy that I’ve had good success with is 440C. This alloy takes a very good surface finish. It takes a high temperature heat treatment.

Here is the process QPQ that I have used very suscessfully over the years

http://www.kolene.com/applications/sbn.asp

Another possibility is Electroless Nickel, probably Hi Phosphorous, on 17/4.
Contact these people about your application.

http://www.electro-coatings.com/kantech.htm

There are several alloys that could take the enviroment but I've never used them with a lip seal at your speeds.

Have you though about making the shaft and seal sleeve as a one piece affair?

 

[rmetzger]

The original design was a one piece shaft / seal runner but installation during assembly would have proved to be nearly impossible in this application.

thanks for the recommendations - I'll so some hunting on those materials