PA46 plastic injection molding parts trapped gas hazards Phenomenon:

1: The dryness of the raw materials is insufficient, and the moisture content is large.

2: The engine compression ratio of the screw design scheme of the equipment extruder is insufficient, so that the relative density of the raw materials is insufficient. But increasing back pressure can be temporarily dealt with.

3: The exhaust pipe of the mold shell is not good. Some mold shells are practically made of breathable steel. It is very likely that the exhaust pipe will be better.

PA46 plastic injection molding parts Materials Analysis:

PA46 decomposes in melts above 330°C, even with short residence times.

The temperature setting of the barrel, the design of the screw, the speed of the screw and the back pressure determine the temperature of the melt. Therefore, it is very important to measure the actual temperature of the melt after injection molding has been carried out for a period of time and when the molding conditions are stable.

[Barrel temperature] Due to the high melting point and high crystallinity of PA46, the barrel temperature needs to be set high enough to provide a uniform melt without being too close to the PA46 degradation point of 330°C.

[Speed/Pressure] Due to the fast curing speed of PA46, higher speeds are required to obtain a good compacted melt and surface finish. Therefore, venting of the mold is required to avoid scorching at the end of the runner.

Compared with PA66, PA46 only needs about half the dwell time. This, combined with its higher mold opening temperature, results in shorter molding cycle times for PA46 compared to other engineering plastics.

[Mold temperature/cooling time] Due to the extremely fast curing speed of PA46, the cooling time is also extremely short. For this reason, the plasticizing time is often the determining factor in the molding cycle. Theoretically, the processing of PA46 can be carried out over a wide range of mold temperatures. In order to reduce the shrinkage in the later stage, increase the fluidity, improve the strength of the weld line and improve the toughness and surface quality, the mold temperature can be increased to 120°C or even higher.

Troubleshooting ideas:

1. The plastic injection molding parts meterial should be fully dried (the drying effect should be confirmed, the moisture content must be less than 0.03%, and a dehumidifying dryer should be used if necessary).

2. Adjust the process:

a. The injection speed is slowed down, which is conducive to the discharge of gas;

b. The temperature of the material is reduced, and the gas is increased by improving the gasification of the material;

c. The back pressure is increased to increase the density of the material;

d. Increase the holding pressure.

3. Adjustment of the PA46 plastic injection molding parts of mold:

Usually, the mold exhaust is strengthened and the gate position is optimized. In addition, the glue point should be large enough, but sometimes the bigger the glue point is, the better. (Excessive glue feeding point will reduce the pressure holding effect, and reverse flow will occur during cooling and shaping.)