Precautions for PA12 Plastic Injection Molding
2026-03-12 10:46:06
Injection Molding
PA12, also known as Nylon 12, features low water absorption, good dimensional stability, low temperature resistance, good flexibility, wear resistance and oil resistance, widely used in precision pipes, pneumatic components, automotive parts and electronic sheaths.
Thorough Raw Material DryingUse a dehumidifying dryer at 80℃–90℃ for 4–6 hours, with hopper holding at 70℃–80℃. Do not replace drying with barrel heating or over-dry for too long to avoid yellowing. Seal the hopper to prevent re-absorption.
Moderate Barrel Temperature
Recommended temperatures: rear 170℃–190℃, middle 190℃–210℃, front 200℃–220℃, nozzle 210℃–220℃. Overheating causes decomposition, discoloration and brittleness; low temperature leads to poor fluidity and short shots.
Sufficient Mold TemperatureRecommended mold temperature: 40℃–80℃, 60℃–80℃ for precision parts. High mold temperature improves crystallization, reduces stress and enhances accuracy and toughness. Ensure uniform cooling channels to avoid warping.
Proper Injection Pressure and SpeedRecommended injection pressure: 60–100MPa, holding pressure 40%–60% of injection pressure. Adopt medium-high speed for smooth filling, avoid jetting and gas traps. Excessive pressure causes flash and high internal stress.
Holding and Cooling ControlHolding time is usually 5–15 seconds; too long increases stress, too short causes sink marks. Adequate cooling time (10–30 seconds) avoids deformation and ejection damage.
Mold and Product Structure Requirements
Good venting is essential with vent depth 0.015–0.025mm. Use round or trapezoidal runners, short and thick. Uniform wall thickness and rounded transitions reduce sink marks and stress. Shrinkage: 0.5%–1.2%.
Shutdown, Purge and Post-ProcessingPurge with PP, PE or special cleaning material before shutdown to prevent carbonization. PA12 parts usually need no conditioning due to low water absorption and good dimensional stability.
Common Defects and SolutionsBubbles and silver streaks: improve drying, lower temperature. Sink marks: increase holding pressure and time. Obvious weld lines: raise melt and mold temperature, improve venting. Brittleness: lower temperature, raise mold temperature. Dimensional instability: stabilize mold temperature, cooling and holding.
