Polycarbonate (PC)

The widely quoted '250 times' figure comes from early-1970s GE/Lexan ball-drop comparisons against thin annealed glass and is not a standard test result. By modern notched Izod testing (ASTM D256), solid polycarbonate sits around 12 to 18 ft-lb/in versus a fraction of that for annealed glass, which works out closer to a 60 to 100 times difference. It is still dramatically tougher than glass and around 30 times the notched Izod impact of cast acrylic, which is why polycarbonate is the default for machine guards, bullet-resistant glazing and riot shields. Polycarbonate scratches more easily than acrylic, so for high-cleaning environments we specify hard-coated grades.

Only UV-resistant grades. Uncoated polycarbonate will yellow and become brittle after a few years of full Australian sun. UV-resistant exterior grades have a co-extruded UV protective layer that blocks degradation and carries warranties of 10 years or more. For outdoor signage we usually recommend acrylic instead, which holds up to UV better than even UV-coated polycarbonate.

Polycarbonate is sensitive to most acrylic solvents (Tensol 12 will craze and crack it) and to many common adhesives. Specialist polyurethane and silicone adhesives bond polycarbonate, but for structural joins we use mechanical fasteners (screws, rivets, captive bolts) with sealant beads. For ballistic and security work, all joints are mechanical.

Specify a hard-coated abrasion-resistant grade (often labelled AR or HC). The factory coating roughly triples scratch resistance and is essential for any panel that will be wiped down often, like sneeze guards and machine windows. Without the coating, polycarbonate scratches more easily than acrylic.

Most machine guards are 6mm to 12mm polycarbonate depending on the impact load and panel size. For impact testing to EN 1837 or AS 4024 we will size the panel to the energy of the worst-case projectile (such as a snapped end mill or thrown fastener). Send us the machine type and we will spec the right thickness.

Yes. Polycarbonate cold-bends to large radii without heat and thermoforms over moulds at around 180°C, which is why it is used for curved security screens, full-face shields and curved machine guards. It must be dried in an oven first (it is hygroscopic), otherwise bubbles appear during forming.

Yes. Standard polycarbonate carries a UL 94 V-2 flame rating; higher V-0 grades are available for electrical enclosures and rail applications. It is self-extinguishing and produces low smoke compared to acrylic.