After the screw barrel is used for a period of time, the screw edge and the nitriding layer of the barrel (when making a new screw, both the screw and barrel will stop the nitriding heat treatment, so there will be about 30-60 silk oxide layers on the surface 2) When worn in both directions, the gap between the two sides increases, causing partial backflow of the plastic, and the output and plasticizing effect are reduced. The screw innovation is to increase the thickness of the screw edge on the old screw to fill the gap to achieve the purpose of increasing the output.
There are currently three main innovation methods in China:
(1) Electric welding: electric welding with alloy electrode (20-30 yuan/kg)
Defects: It is not wear-resistant, it is easy to show false welding, the appearance is not lubricated, there will be blisters, the pellets will appear to stay in the screw, and the material will appear yellow small burnt blocks and black spots.
(2) Spray welding: use a special “acetylene-oxygen” spray gun to spray alloy powder (30-50 yuan/kg)
Defects: no wear resistance, blisters, partial incomplete condensation of the alloy during spray welding, alloy powder will come out of the material during use, resulting in material leakage and die damage
(3) Surfacing welding: use “acetylene-oxygen” to completely condense the 300 yuan/KG imported alloy electrode on the screw
Advantages: Because it is condensation, there is no false welding or blistering.