1. First consider which wall thicknesses need to be filled with air and then decide how to connect them with the airway.

     2. The airway should be balanced and cannot form a circuit

     3. The layout of the airway should be consistent with the direction of the main stream, a larger fillet radius should be used at the corner

     4. The gas nozzle should be placed farthest from the last filling point of the plastic, and be placed at the wall thickness, to maintain a distance of more than 20 from the gate.

     5. When the gas is injected, it must have a clear flow direction and it can reach the end of the airway.

     6. The size of the airway is very important, usually 2 to 4 times the wall thickness. If the airway is too large, fusion lines and gas traps will be produced. If the airway is too small, the gas flow will be out of control.

     7. Cooling should be as uniform as possible, and the temperature difference between inner and outer walls should be as small as possible

     8. Place a block of reasonable flow path radius on the flow path to control the rate of gas flow in different directions