Airway design and gas-needle methods are the key to gas-assisted injection molding. In addition to solving the problem of quality improvement, the airway design of products must pay attention to the excellent rate of production of finished products and reduce costs. In particular, the thickness of products and the size of the airway section and the airway arrangement are very important. , Also pay attention to the gate and gas needle.

(1) Plastic Structure: This article takes the large-size product, PP plastic, and structural design as examples.

(2) Small dimensional deformation: Since the gas is hollow shaped, there is no shrinkage depression after the air passage is hollow, and the dimensional accuracy is good.

(3) Hot Runner Gate: When the hot runner is used, its gate must be an open gate, and it must be processed well without flash, otherwise it will block the gas pin to cause bad exhaust and gas explosion.

(4) Adjust the airway molding pressure: Because the PP material has large shrinkage rate and is easy to sag, the gas pressure should not be too fast and too large. Adjust the airway time and pressure curve to improve the airway cavitation of the product.

(5) Transverse permeation: The thickness of the product near the main air passage is reduced from 4m to 3m m, which significantly reduces lateral infiltration. In the absence of surface contraction, the inlet delay time and high pressure packing are prolonged, and the pressure decrease can also change the lateral infiltration, but When using PP material, the gas is easier to penetrate, so the general thickness needs to be controlled at 3.0 mm, and if it is more than 3.5 mm, the transverse penetration is particularly serious.