leaking seals

[solidworkswell]

I have a 1/4" seal seated onto a TGP 1/4"shaft. The seal is a double lip with a spring and is pressfit into a housing. we never had any problems with leaking.

But this one assembly that has been assembled is leaking. One or two them, may be a bad piece. But all fifteen out of fifteen are leaking where the mate occurs from the shaft. The pressfit holes are measured and all are within spec.

The max temp of the seal is 180°C and 8000RPM. The temperatures i measured are 100-120°F running at 1500rpm.

now whats making it leak....hmm...well the whole assembly as a gear - bearing - then seal.

 

[bogiedreamer]

It is hard to imagine the setup that you are describing without looking at some simple sketches.

What type of seal is it? U-cup, or Lip-seal? How are the lips configured?

If they are U-cup or lip seal then the leakage might be due to bad installation. During installation, the seal might be damaged by a sharp edge bad or installation technique. Also, the mating surface must be better than 16 RMS.
What about pressure?

if you have a sketch or Autocad drawing of the setup I might be able to help you more. Send it to bogiedreamer@gmail.com

 

[scalleke]

What does the shaft surface look like?

If the initial seals have been operating for a longer time on the same position on the shaft the shaft position might have gotten erroded.

In that case reface the shaft surface or position the seals in a slightly different unaffexted area of the shaft.

Best regards.

scalleke

 

[BowTied]

I have had shaft surface finish as an issue, and also seal material change by supplier (durometer, use of regrind in raw material, shipped different material by accident) and also a seal that measures ok with quick caliper inspection, but an optical comparator showed the average ID was to large overall.... some ideas.

 

[svanels]

Maybe too much lubrication oil?

 

[lostbutfound]

Could be several things, here are only a few. I am assuming that the elastomer is rated for the application. And the sizes on everything are correct....

1. Could possibly have some shafts that are not plunge ground therefore creating a leak path similar to threads on a screw.
2. Do shafts have a small burr on the lead in chamfer that could be cutting the seal as you slide the seal onto the shaft? You should be using a bullet to assemble the seal if at all possible.
3. Can you see wear on one side of the seal (possibly misalignment problem) or are they failing instantly?
Good Luck,
bdlong@johncrane.com

 

[Engr777]

Inspect surfaces of seal housing and shaft at the fit locations.