Acrylic or Polycarbonate
smart51 - 5/11/08 at 10:44 AM
I'm going to be making some transparent plastic panels, some vacuum formed headlight "glass" and some side screen windows. Which stuff
is best. PMMA/Acrylic/Perspex or Polycarbonate/Lexan?
What thickness is best for these applications?
Hammerhead - 5/11/08 at 10:48 AM
I'd use polycarbonate.
If you go to amari plastics website it should have the data sheets for the properties of each plastic. Then you can decide. If not call them and they
will send you the book of properties.
I use acrylic for some things I manufacture and it's right for the application. PC is stronger and may have better clarity.
tegwin - 5/11/08 at 10:49 AM
Acrylic will shatter....so not good..
You need polycarbonate...preferably cut with an anti scratch coating on it....
Hammerhead - 5/11/08 at 10:50 AM
oh and don't forget the thickness will reduce quite a lot when vac formed. I use 5mm vac formed 250mm deep and the thickness at the highest point
is reduced to about 1mm
iank - 5/11/08 at 10:52 AM
Have a look here lots of information on how the two perform.
http://www.gcip.co.uk/FAB/boat_car_windows.htm
Polycarbonate with anti-scratch coating for flat panels but IIRC it doesn't bend/form well so the others may need something different.
smart51 - 5/11/08 at 10:55 AM
quote:
Originally posted by Hammerhead
oh and don't forget the thickness will reduce quite a lot when vac formed. I use 5mm vac formed 250mm deep and the thickness at the highest point
is reduced to about 1mm
The max draft depth is 25mm on my mould across an area aproximatly 290mm square. Thinning won't be too bad.
Hammerhead - 5/11/08 at 11:02 AM
quote:
Originally posted by iank
Have a look here lots of information on how the two perform.
http://www.gcip.co.uk/FAB/boat_car_windows.htm
Polycarbonate with anti-scratch coating for flat panels but IIRC it doesn't bend/form well so the others may need something different.
polycarb vac forms pretty well, just not as well as acrylic. I vac formed quite a complex shape in PC the trick is to get it hot enough so it forms
well, but not so hot that it creates little bubbles in the polymer. Trial and error. 
iank - 5/11/08 at 11:09 AM
quote:
Originally posted by Hammerhead
quote:
Originally posted by iank
Have a look here lots of information on how the two perform.
http://www.gcip.co.uk/FAB/boat_car_windows.htm
Polycarbonate with anti-scratch coating for flat panels but IIRC it doesn't bend/form well so the others may need something different.
polycarb vac forms pretty well, just not as well as acrylic. I vac formed quite a complex shape in PC the trick is to get it hot enough so it forms
well, but not so hot that it creates little bubbles in the polymer. Trial and error.
I agree Polycarbonate does vacuum ok, but the coating they put on for anti-scratch doesn't.
Reference: http://www.edplastics.co.uk/Polycarbonate%20Lexan%20Margard.htm
smart51 - 5/11/08 at 11:42 AM
Margard is VERY expensive. The links suggest that Acrylic is 20 times stronger than glass and more abrasion resistant than Polycarbonate, which
itself is 250 times stronger than glass.
If Acrylic is more sractch resistance, easier to vacuum form and strong enough, then its the stuff for me. Its also a bit cheaper than PC.
dhutch - 5/11/08 at 12:44 PM
quote:
Originally posted by smart51
Margard is VERY expensive. The links suggest that Acrylic is 20 times stronger than glass and more abrasion resistant than Polycarbonate, which
itself is 250 times stronger than glass.
If Acrylic is more sractch resistance, easier to vacuum form and strong enough, then its the stuff for me. Its also a bit cheaper than PC.