A bimetallic screw is not simply a combination of two metals, but rather a screw formed by bonding two metals with different properties at the molecular level through a special manufacturing process. Its core design philosophy is "complementary advantages."
1. Selection of Base Material: The main body of the screw, i.e., the base material, is typically made of materials with excellent comprehensive mechanical properties, such as medium carbon alloy steel. These materials have high strength and good toughness, capable of withstanding the complex stresses such as torque and bending moment encountered by the screw under high-speed rotation and high pressure, ensuring the overall structural stability and rigidity of the screw.
2. Application of Wear-Resistant/Corrosion-Resistant Surface Layer: In the critical working areas of the screw, especially on the screw thread surface and metering section where it directly contacts materials such as plastics, rubber, and synthetic fibers and undergoes severe friction and chemical reactions, a layer of high-performance alloy material is clad or welded on using a specific process. This alloy layer typically possesses extremely high hardness, satisfactory wear resistance, and good corrosion resistance.
3. Bonding Mechanism: The bonding of bimetallic screws is not a physical adhesion process, but rather a process involving high temperature and high pressure, which causes interdiffusion between the surface alloy layer and the base material, forming a strong metallurgical bond. This bonding method ensures extremely high interfacial strength, preventing peeling or separation during use and making the screw a high-performance whole.
In short, the design of bimetallic screws cleverly combines the structural support capabilities of the base material with the special protective properties of the surface alloy layer, achieving a balance of rigidity and flexibility, or a combination of strength and wear resistance.
