Flame-retardant PC/ABS has a narrower processing window than many standard ABS grades. Moisture, excessive residence time, high shear, poor venting, and over-packing can quickly create appearance defects or mechanical-property loss.
Control moisture before molding
Drying conditions must follow the supplier data sheet and should be verified with dew point, hopper residence time, and material throughput. Simply setting a dryer temperature does not prove that the resin is dry.
Moisture can contribute to silver streaks, hydrolytic degradation, unstable viscosity, and reduced impact performance.
Use the lowest stable thermal load
Set barrel temperature high enough for stable filling but avoid unnecessary overheating. Long residence time and repeated material recirculation can degrade the polymer and flame-retardant package.
Mold temperature should support surface quality and weld-line strength without making the cycle or demolding unstable.
Balance filling pressure, packing, and venting
Use a staged injection profile and transfer before the cavity is over-compressed. Excessive packing can increase flash and residual stress without improving a gate-frozen region.
Clean and correctly sized vents are essential. Poor venting often appears as burns, short shots, unstable weld lines, or a false need for higher injection pressure.
