Material selection question
Material selection question
(OP)
Howdy all,
I'm trying to select a plastic, but am having a heck of a time. Here are the required properties:
1. Weldable ultrasonically
2. Low moisture absorption (< .03% )
3. UV stable
4. LIght in color
5. SErvice temperature up to 80 deg. C
6. Injection moldable
I have looked at UHMW (not UV resistant except in dark colors), PP (won't take the heat), and PS (terrible weather resistance). These all have low moisture absorption, but fail in the areas mentioned. Any suggestions?
David
I'm trying to select a plastic, but am having a heck of a time. Here are the required properties:
1. Weldable ultrasonically
2. Low moisture absorption (< .03% )
3. UV stable
4. LIght in color
5. SErvice temperature up to 80 deg. C
6. Injection moldable
I have looked at UHMW (not UV resistant except in dark colors), PP (won't take the heat), and PS (terrible weather resistance). These all have low moisture absorption, but fail in the areas mentioned. Any suggestions?
David






RE: Material selection question
That would open up the posibilities of PBT, PET, PC, and ASA
Although the all absorb some moisture, it has negligable effect in dimensions and dimensional stability
Regards
pat
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Material selection question
RE: Material selection question
The plastics I have listed above will not change dimension enough from water absobtion to stress any joints, although the polyesters listed are virtually unglueable, as is PE and PP.
I would be looking seriously at Polycarbonate, or maybe high heat Acrylic.
PC is much tougher and has somewhat better heat deflection temperature, but Acrylic (PMM) has much better UV resistance.
Both are easy to glue, and both absorb a little moisture, but don't change dimensions enough to be a bother.
Regards
pat
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Material selection question
David
RE: Material selection question
RE: Material selection question
Ernst
RE: Material selection question
Sincerely,
Jay Rogers
American Tool & Engineering, Inc.
Visit our website at:
http://www.atemold.com
RE: Material selection question
On thinking about the <.03% moisture requirement, the stress from the "swelling due to moisture" will be so insignificant compared to the stress from thermal expansion differences, that it really is not worth considering. The closest analogy I can think of is that it is like trying to measure to the nearest micron with a wooden rule.
Regards
pat
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Material selection question
RE: Material selection question
It will take the heat. It is very expensive.
Regards
pat
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Material selection question
Mike Glynn
763-428-6180
RE: Material selection question
there is no optimal material just good enough.
Engineering is the science of possible. You have to design
by finding compromisses between cost and material properties
etc.
<nbucska@pcperipherals.com>
RE: Material selection question
absorption limit. Colour might be a problem, there are limited choises for colour, but it should work with your other demands.
Eliassen