The bimetallic barrel for single screw is a kind of barrel moulding 2-3mm thick alloy coat on the barrel inner wall which has excellent corrosion resistance, abrasion resistance and high working temperature. And its useful service life is greatly improved contrast to the common nitrided cylinder. Bimetal has more obvious advantages when processing special plastics to enhance the abrasion life, such as engineering plastic, fluorine plastics, PPO and etc. The company product's single/twin screw, uses special alloy powders being sprayed and welded on the screw's ridge, and uses different alloys and welding methods for the screw of different functions. Materials: Quality 38CrMoAlA Quality power metallurgy raw materials