The basic structure of the extruder includes a transmission device, charging device, barrel, screw, head, and die parts. The key to the extruder is the screw structure and length-diameter ratio of the screw.
The screw structure has a gradual change screw, mutation screw, and screw with a mixing diagram. For PE these three kinds of screws are applicable, with a mixing diagram screw effect is better. Screw length-diameter ratio, due to the limitation of mechanical processing in the past, the screw length-diameter ratio is short, it is affected by plastic plastination, one is not high yield, two is not good quality, now the length-diameter ratio develops to more than 30:1, length-diameter ratio, for product production, high yield, good quality, the length-diameter ratio should be more than 25 is better.
Screw heat treatment is good for long service life, preferably 38CrMnAI, after nitriding treatment. The capacity of the extruder is proportional to the diameter of the screw the capacity of the extruder is proportional to the speed of the extruder the capacity of the extruder is inversely proportional to the clearance of the barrel and the screw, and the clearance should be below 0.25mm.