1. When designing, first consider which wall thickness needs hollowing out, which surface sink marks need to be eliminated, and then consider how to connect these parts to the airway.

2. Large structural parts: Full thinning, partial thickening for airways.

3. The airway should be evenly distributed along the main material flow direction to the entire cavity, and closed-circuit airways should be avoided at the same time.

4. The section shape of the air passage should be close to a circle to make the gas flow smoothly; the section size of the air passage should be appropriate. If the air passage is too small, gas penetration may be caused. If the air passage is too large, welding marks or cavitation may be caused.

5. The airway should extend to the final filling area (usually on the non-exterior surface) but does not need to extend to the edge of the cavity.

6. The main airway should be as simple as possible, the branch airway length should be as equal as possible, and the branch airway end can be gradually reduced to prevent gas acceleration.

7. The airway can be straight without bends (the less the bend the better), the corner radius of the airway should be larger.

8. For multi-cavity molds, each cavity must be supplied with a separate gas nozzle.

9. If possible, there is a second option for not advancing the gas.

10. The gas should be confined within the airway and penetrate into the end of the airway.

11. The exact size of the cavity is very important.

12. It is very important to have a symmetrical cooling of all parts of the product.

13. When using the gate inlet, the flow balance is very important for uniform gas penetration.

14. The accurate amount of melt injection is very important. The error of each shot should not exceed 0.5%.

15. The setting of overflow wells at the final filling site can promote gas penetration, increase airway hollowing rate, eliminate late marks, and stabilize product quality. The addition of a valve gate between the cavity and the overflow well ensures that the final filling occurs in the overflow well.

16. The small gate prevents gas from flowing back into the runner when the nozzle is ingested.

17. The gate can be placed in a thin wall and keep a distance of more than 30mm from the air inlet to avoid gas infiltration and reverse flow.

18. The gas nozzle should be placed in a thick wall and located furthest from the final filling.

19. The outlet direction of the gas nozzle should be consistent with the material flow direction.

20. Keep the melt flow front advancing at an equilibrium speed while avoiding the formation of V-shaped melt flow fronts.

21. When using a short shot, the volume of the unfilled cavity before air intake will not exceed half of the total airway volume.

22. When full-material injection is used, reference shall be made to the pressure, specific volume and temperature diagram of the plastic so that half the total volume of the airway is approximately equal to the volumetric shrinkage of the plastic in the cavity.