Service Temperature of Plastics

I'm making an assumption that you mean thermoplastics.

Heat deflection (or heat distortion)temperature is a good indicator. Usually two numbers are given, one at low stress and one at higher. I recall that 264 PSI is the higher stress number, don't remember the lower number. These are widely published ASTM test numbers.

Ask the technical department of your plastics supplier for help. Upper service temperature limits of thermoplastics is not always straight forward. Molded parts may have built-in stresses caused by the molding process and tool/runner design that influence practical service temperature limits. The properties obtained by the supplier are from carefully molded test specimens designed to reduce internal stresses that would contribute to lower heat deflection temperatures in your molded part.

Mat-web (disclaimer) is a good source and searching for "thermal properties of plastics" and "heat deflection temperature" both produce some good web hits, too.

Thanks lyn,

Yes, I do mean thermoplastics.

I've tried to use the Heat Deflection Temperature as a guide, but in practice it is not a true reflection of the Sevice Temperature(s), no matter how you use it. Comparing figures of various plastics where the figure are known reveals a lack of uniformity/consistency of end result.

Manufacturers seem to be loathe to state the figures, presumably for the reasons you state, and mat-web does not specify temperatures at all. Furthermore, google searches of similar nature to your suggestion came up with nothing of any help.

The reason for my question is that one of our suppliers is claiming that it uses a Nylon 66 - Radilon A HSX - which is suitable for use at 150C continuous and my history tells me that only filled (glass or other) nylons can achieve this. The supplier has no written evidence of the performance claim and I would hate our customer to have deformed parts in the near future and blame us for it. I would expect Nylon 66 to have a continuous service temp. of around 85-100C.

Ozzb,

You're a star!

The "radiciplastics.de" link told me all I wanted to know and confirmed my suspicions.

Neither myself or our Technical Manager located this - probably as it's from a German site?

The "gw" site was another one of those with no information regarding service temperature.

Objective achieved, though.

Thanks again.

Malcolm