I am in the process of testing a new air blower. The impeller is injection molded with glass filled Ultem. After about 10 hours of testing with air temperature around 65C there is a noticeable increase in the material brittleness.  

Do you think these low temperature could increase brittleness in Ultem? I plan on doing some additional testing but I'm curious if there is any experience or advice out there with Ultem brittleness and heat cycling.

Thanks.

Ultem should be OK for a very long time at 65 deg C.

Polycarbonate, polyester or nylon along with a lot of other plastics are all OK for a lot longer or higher temps, even PP would be OK

if it is brittle there must be a cause other than temperature, like chemical attack or fatigue, or you have the temp dramatically wrong

Regards
pat

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

Hello,

I have been reading about plastic pipe and I have to admit to be confused. I would like to know if someone can help me to answer these couple of question.

1.- What does test qualify fiber glass piping for long time service for oil and field fluids?

2.- What additional testing would be needed if frequent pressure fluctuations were expected?

Best wishes,

Howard.

sdk,

Without knowing anything about your part design it is pretty hard to give direction.

But a for good overall fix (and mind you I am shooting from the hip here) I would try using the glass filled PP as Pat is suggesting.

Ultem is very good for use in High Heat and in areas where it may come in contact with automotive liquids.  But the stresses that you are applying are not very good for Ultem.  Such as spinning the part like an impeller.  I would also suspect that the fact the Ultem is glass filled is not helping your situation either.