Injection molding process parameters for common plastics (PC)

Polycarbonate (PC)
Barrel temperature   Feed zone 70~90 ℃ (80 ℃)
                                   Zone 1 230~270 ℃ (250 ℃)
                                   Zone 2 260~310 ℃ (270 ℃)
                                   Zone 3 280~310 ℃ (290 ℃)
                                   Zone 4 290-320 ℃ (290 ℃)
                                   Zone 5 290-320 ℃ (290 ℃)
                                   Nozzle 300~320 ℃ (290 ℃)
Note: The temperature in parentheses is recommended as the basic set point, with a stroke utilization ratio of 35% and 65%, and a module flow length to wall thickness ratio of 50:1 to 100:1

Melt temperature: 280~310 ℃
Material barrel constant temperature: 220 ℃
Mold temperature: 80~110 ℃
Injection pressure: Due to poor material fluidity, a high injection pressure is required: 130~180MPa (1300~1800bar)
Pressure maintaining pressure: 40%~60% of injection pressure; The lower the holding pressure, the lower the stress of the product
Back pressure: 10-15MPa (100-150bar)
Injection speed: depends on flow length and cross-sectional thickness: thin-walled products require rapid injection; If good surface quality is desired, use multistage slow injection
Screw speed: maximum linear speed is 0.6m/s

Making the plasticizing time correspond to the cooling time; The screw requires a large torque
Metering stroke: (0.5~3.5) D
Residual material amount: 2~6mm, depending on the metering stroke and screw diameter
Pre drying: drying at 120 ℃ for 3h; Keeping the moisture content below 0.02% will improve the mechanical properties
Recovery rate: up to 20% recycled material can be added; Higher recycle ratio will maintain heat resistance, but reduce mechanical properties
Shrinkage: 0.6% to 0.8%, if glass reinforced type, 0.2% to 0.4%
Gate system: The gate diameter should be at least 60% to 70% of the maximum wall thickness of the product, but the gate diameter should be at least 1.2 mm
        (The gate slope is 3-5 °, or 2 ° is required for products with good surface quality); For smaller products with uniform wall thickness Point gate.

        If production is interrupted during machine downtime, operate the machine like an extruder until there is no plastic extrusion and the temperature drops to about 200 ℃: clean the material barrel, use high viscosity PE, extract the screw from the hot material barrel, and use a wire brush to remove the residual material.