Tungsten Copper Electrode New Process

With the rapid development of EDM (Electrical Discharge Machining) industry, it has higher and higher requirements for the used electrode. Both tungsten copper with high content of W (mass fraction of W reaches 50%-90%) and tungsten copper with high content of Cu (mass fraction of W reaches 50%-90%), the most widely used are mixing method and infiltration method. Theoretically, the mixing method has simple operations and can fabricate tungsten copper products with any ratio of W and Cu. But the powder grain of raw material by this kind of conventional process is too large and the density distribution is uneven, which is difficult to fabricate tungsten copper electrode with compact structure after pressing and sintering process.

While the infiltration process is suitable to fabricate tungsten copper with 8%-40% content of Cu, tungsten skeleton infiltrated by copper in molten state to obtain the densification. Although the infiltration process is the most widely used in tungsten copper electrode now and it has stable working properties, it also has some problems, such as many controlling parameters, difficulties in porosity controlling, difficulties in porosity distribution and so on. So the relevant scholars and researches have further explosion surrounding the raw material preparation and molding process in recent years. Some new technology has gradually developed, which is more practical and operational effects are:

1. Pre-alloying: Its powder refinement and even micro-alloying, so as to achieve increased activity and split the purpose of promoting densification by mechanical and high energy ball milling;

2. Ultrafine particle / nano powder: By the addition of grain growth inhibitors, high-energy ball milling, adding elements and changing the material of the powder form and other methods to refine, even to the nanometer level;

3. Thermoforming: it is pre-loaded with a good blend in the mold cavity, rapid molding under heat and pressure to achieve integration and briquettes pressed sintered compact so as to achieve the densification effect;

4. Injection molding: the process is suitable for the manufacturing of parts with complex structure and a smaller volume, which prepared a uniform structure, precise size, but the control of process parameters is more complex, and higher production cost of the mold;

5. Coated powder process: based on Cu cladded by W powder, which will be an oxide, a compound or compound solution both doped together, dried calcined powder coated after the reduction.

In addition, vacuum sintering, microwave sintering, activated sintering, plasma arc welding sintering process all have own advantages and application scope. Here we mainly introduce the coated powder process by thermal chemical method.