Transparent Nylon PA12 Injection Molding Process

2026-02-06 
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Raw material pretreatment
Vacuum drying: 85 ± 5 ℃/5 ± 0.5h;
Moisture content ≤ 0.05%;
After drying, the material cylinder stays for ≤ 1 hour
1. Dry upon opening, seal before use (moisture-proof film+desiccant);
2. Use as soon as it dries
1. Disable ordinary ovens;
2. It is strictly prohibited to use the machine if the moisture content is greater than 0.05%;
3. If the material cylinder stays for more than 1 hour, it will be re dried
The raw materials have no moisture absorption or clumping, and the particles are uniform
Equipment Requirements
Locking force ≥ 800kN;
Nitriding anti sticking screw (aspect ratio 22:1-25:1);
Spray nozzle with anti drooling device (aperture 2-3mm)
1. Preheat the screw in advance;
2. Regularly clean the nozzle with anti blocking materials
Disable non nitriding treatment of screws, which may cause uneven plasticization of sticky materials
There is no abnormal noise during the operation of the equipment,
Plasticizing uniformly
Barrel temperature (three-stage)
Section 1: 220 ± 5 ℃;
Section 2: 240 ± 5 ℃;
Three stages: 250 ± 5 ℃;
Spray nozzle: 245 ± 5 ℃. The temperature gradually increases from the feed inlet to the spray nozzle, with a range difference of 10-20 ℃
1. Temperature above 260 ℃ is prone to yellowing and degradation;
2. Insufficient plasticization at temperatures below 210 ℃
The melt has no yellowing or clumping,
Uniform liquidity
Mold parameters
Mold temperature: 90 ± 5 ℃;
Demoulding slope: 1.5~2 °;
Flow channel: large water outlet (diameter 8-10mm);
Gate: Side gate/fan-shaped gate (3-5mm wide);
Exhaust groove: depth 0.03~0.05mm/width 8~10mm;
Polishing of cavity mirror surface Ra ≤ 0.05 μ m
1. Preheat the mold in advance with the mold temperature machine;
2. Regularly clean the exhaust duct without blockage
1. Mold temperature<80 ℃ is prone to weld marks/foggy surfaces;
2. Disable fine water nozzles/sprues;
3. Exhaust groove depth>0.05mm
Easy to overflow material
The mold cavity is free of scratches and impurities,
Smooth demolding
Injection parameters
Injection pressure: 90-110MPa;
Injection speed: 70-85%;
Pressure holding: 60-75MPa;
Pressure holding time: 7 ± 1s;
Cooling time: 10 ± 2s
1. High voltage and medium speed ensure charging;
2. Gradually reduce the pressure while maintaining pressure,
Avoid shrinkage marks
1. Insufficient filling under pressure<80MPa, internal stress cracking under pressure>120MPa;
2. When the speed is less than 60%, there are obvious weld marks
The product has no shortage of materials, no shrinkage marks, and no flying edges
Post-processing
Immediately seal after demolding (moisture-proof film+desiccant);
Optional flame polishing (400~500 ℃ rapid surface scanning)
After sealing, place in a dry environment (humidity<40%)
Exposure to air for more than 10 minutes after demolding, prone to moisture absorption and deformation/foggy surface
No polishing scratches on the surface, no damage to the seal
Final Inspection
1. No bubbles, silver lines, or weld marks;
2. Light transmittance ≥ 88%, haze ≤ 2%;
3. Dry dimensional tolerance ± 0.1mm;
4. The surface is scratch free and matte free.