Tungsten Copper Contact Tip

Tungsten copper contact tip is a kind of welding consumables and it is generally located in the end of welding torch, which play a role in delivering welding wire. According to the hole shape, it can be divided into round, square, ellipse, triangle and so on. Common used materials for contact tips include pure copper, brass, beryllium copper, chromium zirconium copper, beryllium cobalt copper, etc.

In the resistance welding process, not only requires the contact tip has good electrical conductivity, but also required at high temperatures still has high strength, wear resistance and corrosion resistance to electrical properties. In practical, the contact tips use pure copper and beryllium copper, which have poor wear resistance and during welding process will easily spatter adhesion. It cause clogging of the tip or the wire and the contact tip bonding, which make the contact tip failure. Furthermore, replacing contact tip frequently will affect the welding performance and decrease the overall efficiency. Compared with pure copper, chromium zirconium copper and beryllium cobalt copper has higher hardness and better wear resistance at room temperature. But it has fewer sources, relatively complex process and higher cost.

Tungsten copper has both advantages of W and Cu, which not only has higher hardness, but also has excellent wear resistance, galvanic corrosion and higher softening temperature. Whether as the electrical resistance welding electrode with special requirements for the stress or as the contact tip used in arc welding, tungsten copper material has a great advantage, which is an important role of the electrical processing and welding occasion. Tungsten copper contact tip is sintered by tungsten and copper composite powder and the tungsten skeleton uniformly distributed in the copper matrix. When the temperature exceeds the melting point of copper, tungsten skeleton liquid copper can stick as a huddle and constitute a good conductor of heat passage, so tungsten skeleton area overheating does not occur in the process.

Theoretically, the room temperature strength of metal depends on two basic factors: one is binding force of metal atom, the other one is the resistance to dislocation motion. Common by increasing resistance to dislocation movement to improve the strength and work hardening methods are split out strengthened. However, these methods the effect of increasing temperature decreases until it disappears, and some rely precipitates precipitation hardening copper alloy, when raised to a certain temperature, the precipitate into the matrix meet again, so that a sharp decline in the strength of the material. By comparison, tungsten copper material does not has phase change, recrystallization phenomena at high temperature and the physical and chemical properties are stable.

The experiments show that 70W-Cu has higher hardness and better electrical conductivity than beryllium cobalt copper, and its softening temperature is twice more than beryllium cobalt copper, so as for flash butt welding electrode wear or require a higher arc welding contact tip applies quite well. There is a comparison between tungsten copper contact tip and brass contact tip:

From the table we can see that the contact tip compared to tungsten copper contact tip brass longer life, better welding performance, which can effectively improve the overall efficiency. In addition, in the process of vertical welding, when the thickness of the weldment 22-28mm, wire diameter φ2.4mm, 2.8mm the pore size of the contact tip, tungsten copper contact tip and chromium copper contact tip after welding has a great difference in wear. Tungsten copper welding contact tip at 20m, the circular aperture can remain unchanged, ensure the continue welding; The chromium copper welding contact tip about 2m, circular conductive mouth to occur due to poor abrasion resistance unilateral eccentric, expand the aperture and are unable to continue welding. Overall, tungsten copper contact tip has higher hardness, better thermosetting, wear resistance, excellent arc ablation resistance, anti-adhesion, which is a kind of contact tip materials with a broad application prospect.