Adding info as I find it for others who may be interested.
The contractors who do most of out LEXAN guards & such have a series of long, straight rods that resemble electric oven heater elements. They simply lay the LEXAN on the element, turn it on, and wait for it to bend right on the line from gravity. Don't know what temp they use, but a few scraps would probably get you very close.
THERMAL PROPERTIES:
Melting point : 310° F
Heat deflection at 66 psi (ASTM D 648) : 285° F
Heat deflection at 264 psi (ASTM D 648) : 270° F
Maximum serving temperature for short term : 275° F
Maximum serving temperature for long term : 240° F
Polycarbonate sheet must be dried before thermoforming because polycarbonate absorbs moisture at a high rate. Trapped moisture forms vapor above 250°F, and the vapor expansion creates bubbles in the sheet. Sheets of polycarbonate should be placed in a dehumidifying air circulating oven for predrying with approximately 1" separation between sheets. Oven temperature should be 250°F and monitored with controls. Recommended predrying time periods are shown below. A note of caution-polycarbonate sheet begins absorbing moisture immediately upon removal from the predrying oven. The rate of absorption is dependent upon the ambient dew point. For this reason, it is crucial to transfer the sheet directly to the forming machine as quickly as possible.
Gauge
Drying Time (Hours)
.093" 4
.125" 6
.187" 14
.250" 24
San Diego Plastics, Inc.
http://www.sdplastics.com/polycarb.htmlTAP Plastics
http://www.tapplastics.com/shop/category.php?bid=11&Port Plastics
http://www.portplastics.com/architect/page22.htmlhttp://www.trivalleyautoglass.com/custom_cut_glass.cfmsign manufacturers
2005 X? spoke with a polycarbonate representative from GE (the company that manufactures Lexan) and they have all sorts of experts who will help you with this project. In fact, a person included on my conference call was a thermoforming expert.
One very unhappy boatbuilder I know had to replace all of his installed windows because he cleaned up a bit of caulking around the windows with some acetone.
Geo