Copper tungsten electrodes manifest excellent EDM performance when machining carbide tungsten. They are preferable than copper electrodes for use in many micro EDM machining processes such as small hole drilling to specific materials. Infiltrated tungsten copper, sintered and pressed by powder metallurgy, has an integral microstructure. EDM’s electrodes with a uniform structure can yield high-quality roughness on the workpiece surface.
High tungsten content imparts both high melting point and density to copper tungsten electrodes. Thus, tungsten provides the electrode a solid spark erosion resistance. Copper tungsten’s 20%-40% copper content is largely responsible for its excellent conductivity. High electrical and thermal performance is essential to maintaining an electrode’s material removal rate, which determines its cutting speed.
Composition and Properties
|W90Cu10||W 90% Cu 10%|
|W85Cu15||W 85% Cu 15%|
|W80Cu20||W 80% Cu 20%|
|W75Cu25||W 75% Cu 25%|
|W70Cu30||W 70% Cu 30%|
|W60Cu40||W 60% Cu 40%|
|Thermal Conductivity||180-300 W/m·K|
|Electrical Conductivity||32-60 IACS % Min.|
Outstanding Electrode Wear Rate
The heightened melting point and density imparted by tungsten guarantee high wear resistance for copper tungsten electrodes, even in poor flushing conditions. The EDM machining process rapidly increases tremendous heat between the electrode and workpiece. Indeed, the working temperature of EDM machining is commonly 10,000 °C, a temperature found in many stars. High melting point and density are critical factors which determines how much thermal energy an electrode can withstand. For this reason, copper tungsten electrodes exhibit an outstanding arc resistance in such an environment.
Excellent Thermal and Electrical Conductivity
Tungsten copper exhibits impressive thermophysical properties, such as outstanding thermal and electrical conductivity and thermal expansion. These are significant attributes for electrodes used in EDM processes. It is because these attributes increase MRR without compromising the electrode’s erosion rate.
Copper infused tungsten electrodes are preferable to pure tungsten electrodes in a variety of ways. In addition to having a high MMR rate, especially when the EDM process operates in a low pulse current, tungsten copper electrodes produce a higher cutting speed. They are also more cost-efficient because of their lower production cost in comparison with pure tungsten.
The machining of copper tungsten composites into EDM electrodes presents significantly fewer complications than the machining of either pure copper or pure tungsten. Pure tungsten is hard to machine because of its inherent brittleness. Pure copper is because of its ductility.
For example, pure tungsten is both hard and brittle at room temperature. The high machining speeds must be maintained. Cutting tools with a low wear rate are required.
Pure copper, due to its normal ductility, becomes gummy during machining. Thus, it requires additional time to remove burrs on machined edges and surfaces. Copper tungsten composites in a variety of content ratios largely eliminate these and other mechanical limitations.
High-Quality Surface Finish
The surface integrity of EDM machined workpieces reflects its surface finish quality. The integrity performance is dependent on the quality of copper in tungsten copper electrodes. There are two main reasons for this.
First, high MMR is an essential attribute for improving the workpiece’s surface integrity. Copper confers its excellent thermal conductivity to the alloy, thereby increasing MMR.
Second, evenly distributed copper increases the structural integrity of the tungsten copper electrodes. Advanced powder metallurgy allows molten copper to uniformly infiltrate the pre-sintered tungsten skeleton.