It is emphasized here that the two important parts of plastic extruder screw and barrel, one is the slender thread rod, the other is the small and long hole, their machining and heat treatment process are more complex, and the accuracy is more difficult to guarantee. Therefore, the wear of these two parts after repair or replacement of new pieces, from an economic perspective must be comprehensively analyzed. If the repair cost is lower than the cost of replacing the new screw rod, it is decided to repair, which is not necessarily the right choice. The comparison between repair cost and update cost is only one aspect. In addition, the cost of repair and repair after the use of screw time and update costs and replacement screw use time ratio. It is the right choice to adopt a low ratio plan.

Plastic extruder screw and barrel manufacturing, at present domestic commonly used materials are 45, 40Cr and 38CrMoAlA. Imported material for manufacturing screw and cylinder in extruder, commonly used alloy steel is 34CrAINi7 and CrMoV9. The yield strength of this material is about 900MPa. After nitriding treatment, the hardness is above 1000HV, which is wear-resistant and has good corrosion resistance.