The common structure of cartridge heater is the same as that of electric heat pipe. It is generally composed of five parts: insulator, sealing material, leading-out rod, filling material, electric heating wire, metal sleeve and terminal. The helical heating wire and the leading-out end are located in the middle of the metal sheath. It is manufactured by threading the helical heating wire into stainless steell tube, copper tube or aluminum tube, such as crystalline magnesium oxide powder (also available in alumina or clean quartz sand). Then use the tube shrink machine to shrink the diameter of the pipe, so that the oxide medium is dense, to ensure that the electric heating wire and air isolation, the central position does not occur deviation and hit the wall of the pipe. Unit area calorific value can increase greatly. Service life can also be increased accordingly. http://www.etdzheater.com