Moisture Control
Polycarbonate belongs to polyester plastic. Polyester Plastic will be easy to occur hydrolysis and broken bond, decreasing molecular weight and substance intensity phenomena under high temperature, even if it’s in low moisture. So before processing to shape, dry first to avoid deducing shaped products’ mechanical strength or air bubble, craze and other surface defects. It’s suggested to bake for 2 to 4 hours in the temperature of 120℃, if it is added reuse material, please prolong the dry time. And if the dried particles are settled in air for more than 15 minutes, please redry.

Table 1: Injection Molding Suggested Temperature

	6170	807S	907S	Fire-retardant ABS	PC/ABS	Strengthen PC
Mould Temperature	60-90	80-90	60-80	40-60	50-60	50-80
fusant	265-270	260-275	255-275	200-210	210-220	240-245
Nozzle	210-240	200-220	210-225	200-210	210-220	210-230
Forepart	265-280	260-285	260-275	220-225	235-240	255-260
Mid-part	260-270	255-270	255-270	210-220	225-235	250-255
After-body	250-265	250-265	250-265	200-210	210-230	245-250

Molding Processing
Injection Molding Processing
Normal injection molding machines can all be used for processing polycarbonate, while the choice of injection machine lies on capacity of mould cavity. Generally speaking, when mould cavity capacity equals to 20% to 75% of material bucket quantity, the effect will be better, meanwhile, the best one is between 40% and 60%; the L/D of screw should be at least 15:1, and the best is 20:1; the compression ratio should be1.5:1 to 3.0:1.
If the injection moulding pressure is bigger, the internal stress will be reduced more during the process, and quickly fully fill mould cavity, but when the pressure dwell and dwell time is shorter, it is better. Injection is determined by the design of sprue, If sprue is too small, causing higher velocity and air lines. Normally we use the slow velocity at the beginning, then changes to free one.
During the process of molding, the rotate speed of screw is set 50-70RPM, and the back pressure of screw can improve exhaust functions, it will make the melt and mix of plastic more equally and stable when using toner or color masterbatch. The temperature of cylinder and mould are all related to the fusion index of polycarbonate, please see Table 1 for details.