[simpits-tech] Forming polycarb..

[Darren Beaumont]

Sean,

Temperature depends on the material used and the type of forming you are
doing.

Material = "Regular" acrylic plastic - MIL-P-6886
Sheet Thickness 0.125"
Simple curve = 113C or 245F
Stretch forming, Male & Female moulding, Vacumum forming without form = 140C
or 284F
Vacuum forming with female mould = 145C or 293F

Sheet Thickness = 0.250"
Simple curve = 110C or 230F
Stretch forming, Male & Female moulding, Vacumum forming without form = 135C
or 275F
Vacuum forming with female mould = 140C or 284F

Material = Heat Resistant acrylic plastic, MIL-P-5425 and craze-resistant
acrylic plastic - MIL-P-8184
Sheet Thickness 0.125"
Simple curve = 135C or 275F
Stretch forming = 160C or 320F
Male & Female moulding = 180C or 356F
Vacumum forming without form = 150C or 302F
Vacuum forming with female mould = 180C or 356F

Sheet Thickness = 0.250"
Simple curve = 135C or 275F
Stretch forming = 150C or 302F
Male & Female moulding = 170C or 338F
Vacumum forming without form = 145C or 293F
Vacuum forming with female mould = 170C or 338F


Get hold of the FAA Acceptable Methods, Techniques and Practices manual,
free download from FAA site, but a massive document.  I've got the book,
which is about 1 and a half inches thick.  It tells you in there how to form
acrylic amongst other things.

Weblink to the AC website =
http://av-info.faa.gov/dst/ACreference/acindex.htm
Link to the FAA Acceptable Methods, Techniques and Practices manual =
http://av-info.faa.gov/dst/43-13/ - You want chapter 3, Section 3.

Darren

-----Original Message-----
From: simpits-tech-admin@simpits.org
[mailto:simpits-tech-admin@simpits.org]On Behalf Of Sean Galbraith
Sent: 12 June 2002 19:19
To: simpits-tech@simpits.org
Subject: Re: [simpits-tech] Forming polycarb..


At 12:50 PM 6/12/02 +0100, you wrote:
>On Wed, 12 Jun 2002, Sean Galbraith wrote:
>
> > Well it's time to learn a new skill :)
> >
> > I have almost completed the front windscreen on the A-4 so next up is
the
> > main canopy.. complete with complex curves!
> >
> > Does anyone have ideas/suggestions for how I can achieve this?  The
canopy
> > is being framed with aluminium, so strength is not the real issue, just
> the
> > shape.
>
>Having talked to our materials guys, and perusing the materials database -
>Acrylic sheet was recommended to me since this responds well to heat in
>that once its shape is changed, it'll stay changed!

Cancel Poly, order Acrylic. Check.


>You need to uniformly heat the sheet until it becomes plyable enough to
>take up the shape you need, then allowed to cool. The big problem is
>providing the uniform heat.  I tried - and failed ;)

That's no problem,  I have access to an oven 24' x 10' x 8'..... that
should do it.  What sort of temperature are we talking, ballpark?

S.


>--
>
>Roy.
>
>
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