Common materials for barrel and screw: Nowadays, the mo […]
Common materials for barrel and screw:
Nowadays, the most commonly used and common barrel and screw materials in my country are No. 45 steel, 40Cr, nitride steel and 38CrMOAl. The following describes the performance requirements of these materials one by one, as follows:
1. No. 45 steel is cheaper, cost-effective, and has good processing functions. The only disadvantage is: poor wear resistance and corrosion resistance. Heat treatment: quenching and tempering HB220-270, high-frequency quenching HRC45-48.
2. The function of 40Cr is stronger than that of No. 45 steel, but we must often coat it with a layer of chromium to improve its corrosion resistance and wear resistance. However, it has higher requirements for the chromium plating layer. If the plating layer is too thin, it is easy to be worn, and if it is too thick, it is easy to peel off. After peeling, it will accelerate its corrosion. The heat treatment method is: quenching and tempering HB220-270, hard chrome plating HRC>55.
3. The comprehensive functions of nitrided steel and 38CrMoAl are relatively excellent, and their application functions are also relatively extensive. Generally, the nitride layer is 0.4-0.6 mm. However, this material has relatively low resistance to corrosion by hydrogen chloride and is relatively expensive. Its heat treatment method: tempering HB220-270, nitriding HRC>65.
Material requirements of the barrel and screw:
We know from the extrusion process that the screw is operated under high temperature, certain corrosion, strong wear and high torque. Therefore, the barrel screw must meet the following requirements:
1) High temperature resistance, no deformation under high temperature;
2) Wear resistance and long life;
3) Corrosion resistance, materials are corrosive;
4) High strength, can accept high torque and high speed;
5) It has a good cutting function;
6) After heat treatment, the residual stress is small, and the thermal deformation is small.