Plastic ring: ID vs. temperature 1

[Indicator1]

I have a plastic ring with a certain ID value at room temperature.
How can I estimate ID at -65 deg C? at 125 deg C?
Do I need to run FEA, or calculations, please?
Thanks.

 

[patprimmer]

You need the co-efficients of thermal expansion over the temperature range involved, then do the very simple mathematics.

The co-efficient of thermal expansion will change over that temperature range. If the currently undisclosed plastic is fibre reinforced, the co-efficient of thermal expansion will vary considerably according to direction of flow when moulded.

Regards
Pat
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[Indicator1]

Patprimer,

Thank you for explanation.
The plastic is ULTEM 1000, and I was lucky to get a single value of CTE.
I am currently using a simple formula, assuming it expands in both directions along the radius.
I wonder whether there are better ways to estimate ID.

 

[ivymike]

Yes, it would be better to use a temperature-varying CTE.

 

[patprimmer]

The CTE will vary significantly over that temperature range.

The biggest changes will be as it passes through second order transition points such as GTT.

I do not personally have data on Ultem 1000. Ask Sabic for more detailed data.

Regards
Pat
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[Indicator1]

Patprimer,
Sorry, I dont know how to get to Sabic.
Thank you.

 

[patprimmer]

I was just astounded to find google gave me 700,000 hits on the word Sabic. You should try it. It is quite amazing.

Regards
Pat
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[Indicator1]

Sabic did return "0" to ULTEM 1000...

 

[MintJulep]

assuming it expands in both directions along the radius

That's not a good assumption to make.

thread391-246558

 

[telecomguy]

patprimmer, here's one for you...

http://lmgtfy.com/?q=Sabic

And yes MintJulep, I saw that and was curious if he meant what it sounded like.

-tg

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[patprimmer]

http://www.matweb.com/search/datasheet.aspx?matguid=578c0713b95d4db4a8d8c0c53a872ffb&ckck=1

This gives along and across the flow over a fairly wide temperature range, but not so wide as you require.

YOU will need to contact Sabic directly if you hope to get more detailed information

Regards
Pat
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[TVP]

Sabic Innovative Plastics is the new name for the former GE Plastics. Here is a link to the Sabic IP site for Ultem:

http://www.sabic-ip.com/gepapp/Plas...ries=Unreinforced&search=Search#searchresults

 

[Indicator1]

To TVP:

Thank you for this link!