Bushing for 100C, 212F, replace PEEK with cheaper polymer?

[mailtrams]

Hello.

I am thinking of if there is a cheaper polymer than PEEK for a bushing.
The max surface pressure is 20Mpa 2.9psi.
The motion can be described as slightly pivoting.
And the shape of the bushing is:
Inner diameter = 15mm , 0.6 inch
Thickness = 1.5mm , 0.06 inch
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They are going to be injection moulded.
We will do around 300 000 pieces but the most will done in POM for lower temperature applications.

Thanks

 

[patprimmer]

Have you tried nylons 66 and 4.6

Regards

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[mailtrams]

Thanks for the answer.
I forgot to say that they must be food grade.
I don't think they are food grade?

 

[patprimmer]

I am sure they can be. They can even be medical implant grade.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[mailtrams]

Thanks again, can the nylon 66 be used in this temprature in water? The application is a steamer.

 

[patprimmer]

Ummm what temperature.

What expected life.

Pure water, typical water supply water or something else.

Nylon 66 will degrade in water at 100 deg C

I would need to look up some tables to determine the rate.

Unfortunately the best heat and hydrolysis stabilisers loose the food contact status.

Life would be a lot easier if you stated most of the requirements up front instead of bringing them out one at a time.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[kiwinjuneer]

There are special grades of Nylon that absorb less water but still need to watch clearances or the bush will grab the shaft/axle. Also use a resin with Aramid or Carbon fiber to aid stability. Carbon will cause premature wear of the other surface though, where the Aramid (Kevlar) will not.

We use this in down-hole (oil/gas) drilling situations where there is oil, water, gas etc at temperatures up to 140 C without problems but the fiber is important.

Cheers Geoff

PS I'm assuming that the 2.9 psi is the correct pressure?

 

[Pud]

Some cheaper alternatives to consider:

PPA (LNP and others)
PPS (Glass and PTFE filled) - e.g. Ticona Fortron
Partially aromatic nylons such as Grivory made by EMS Chemie.

PPA has a narrow processing window but any half-decent moulder should be able to run it.

PPS needs 135 Deg C tool temp so unless tool is insulated and/or elecrtically heated choose last...

Grivory has potable water approvals in the EU - you will have to check with manufacturers for the others.

Cheers


Harry