Polycarbonate (PC)

(1) Barrel Temperatures

Feeding Zone: 70–90°C (80°C)
Zone 1: 230–270°C (250°C)
Zone 2: 260–310°C (270°C)
Zone 3: 280–310°C (290°C)
Zone 4: 290–320°C (290°C)
Zone 5: 290–320°C (290°C)
Nozzle: 300–320°C (290°C)

The temperatures in parentheses are recommended as baseline settings, with a stroke utilization of 35% and 65%, and a flow-length-to-wall-thickness ratio of 50:1 to 100:1.

(2) Melt Temperature: 280–310°C
(3) Barrel Constant Temperature: 220°C
(4) Mold Temperature: 80–110°C

(5) Injection Pressure:
Due to poor material flowability, high injection pressure is required, typically 130–180 MPa (1300–1800 bar).

(6) Holding Pressure:
40–60% of the injection pressure. Lower holding pressure results in lower internal stress in the part.

(7) Back Pressure: 10–15 MPa (100–150 bar)

(8) Injection Speed:
Mainly depends on flow length and cross-sectional thickness. Thin-walled parts require fast injection. For better surface quality, use multi-stage slow injection.

(9) Screw Speed:
Maximum linear speed: 0.6 m/s. Match plasticizing time with cooling time. High torque is required for the screw.

(10) Metering Stroke: (0.5–3.5)D
(11) Cushion: 2–6 mm, depending on metering stroke and screw diameter.

(12) Pre-drying:
Dry at 120°C for 3 hours. Maintain moisture content below 0.02% to achieve better mechanical properties.

(13) Regrind Ratio:
Up to 20% regrind can be added. Higher regrind ratios maintain better thermal resistance but reduce mechanical properties.

(14) Shrinkage: 0.6–0.8%. For glass-reinforced grades, shrinkage is 0.2–0.4%.

(15) Gating System:
Gate diameter should be at least 60–70% of the maximum wall thickness, but not less than 1.2 mm. Pin-point gates can be used for small parts with uniform wall thickness.

(16) Machine Shutdown Procedure:

If production is interrupted, run the machine like an extruder until no more plastic is extruded, and reduce temperatures to around 200°C. Clean the barrel using high-viscosity PE. Retract the screw from the heated barrel and clean residual material with a wire brush.

(17) Barrel Equipment:
Standard screw, non-return valve, and open nozzle.