1. Firstly, considering the suitable wall thickness areas needs to be injected and hollowed out, and then decide how to connect them with the gas channel;
2. The gas channel should be arranged in balanced and cannot return back;
3. The layout of the gas channel should be consistent with the main material flow direction, and a larger fillet radius should be used at the corners;
4. The gas nozzle should be placed at the farthest place from the last filling place of the plastic, and placed at the wall thickness area, keeping a distance of more than 20mm from the gate;
5. When the gas is injected, it must be a clear flow direction and it can go to the end of the gas channel;
6. The size of the gas channel is very important, generally 2~4 times than the wall thickness, if the gas channel is too big will cause welding line and air trapping, and if gas channel is too small will cause the gas flow out of control;
7. The cooling should be as even as possible, and the temperature difference between the inner and outer part should be as small as possible, then make a block in half diameter gate area to control the gas flow speed in different directions.