The length of the heating wire in the heating tube before it is pulled apart cannot be shorter than 1/4 of the tube; if the heating wire is spirally unfolded in the heating tube, the gap between the wire and the wire should be 2-3 times the diameter of the heating wire; After winding the wire, the heating wire is spring-shaped, then the outer diameter of the spring-like heating wire should occupy 2/3 of the inner diameter of the iron pipe.
The production processes I have been exposed to include powder addition, vibration, tube shrinkage, etc.
