Wire EDM Materials
Electrical discharge machining is a machining method primarily used for hard metals or those that would be very difficult to machine with traditional techniques. Wire EDM typically works with materials that are electrically conductive. EDM can cut intricate contours or cavities in pre-hardened steel without the need for heat treatment to soften and re-harden them. Conductive materials for EDM, include:
- Carbon Graphite
- Carbon Steel
- High Alloy
- Stainless Steel
Conductive Materials used for EDM
Electrical discharge machining (EDM) makes it possible to work with metal for which traditional machining techniques are ineffective. There are numerous electrically conductive wire EDM materials that can be utilized effectively within the process. Using recurring electric discharge, it is possible to cut small, odd-shaped angles and detailed contours or cavities in hardened steel as well as exotic metals such as titanium and carbide. The conductive materials for EDM which we utilize include the following:
Bronze is an alloy of copper and tin, that does not resist wear as well as copper or tungsten, but is much easier to machine and can be die-cast or extruded for specialized applications. Wire EDM materials such as bronze do not need to provide wear or arc erosion resistance since new wire is fed continuously during the EDM wiring cutting process.
Wire EDM materials such as copper and its’ alloys have better EDM wear resistance than bronze but is more difficult to machine compared to other conductive materials for EDM. Copper is also more commonly expensive than other similar wire EDM materials. Additionally, copper is highly conductive and strong. It is useful in the EDM machining of tungsten carbide, or in applications requiring a fine finish.
Conductive materials for EDM such as tungsten are produced using powder metallurgy processes. Tungsten is very expensive compared to other electrode materials but is useful for making deep slots under poor flushing conditions and in the EDM machining of tungsten carbide. Tungsten materials are also used in resistance welding electrodes and some circuit breaker applications.
Carbon graphite provides a cleaning action at low speeds. This advanced wire EDM material was one of the first brush material grades developed and is found in many older motors and generators. It has an amorphous structure.
The key benefits of carbon steel are cost and availability. Carbon steel can be effectively machined using EDM methods. Carbon steel is also the most common, versatile, and often lowest-cost option when you require shims, precision stampings, spacers, washers, and other similar products.
Traditionally, superalloys such as Inconel have been difficult to machine using conventional cutting and grinding methods due to its high strength at elevated temperatures. However, due to wire EDM methods, Inconel can now be successfully machined.
A wire EDM material such as stainless steel has many distinct advantages. Stainless steel has excellent fatigue and impact resistance and does not need to be finished, which reduces overall delivery time. This conductive EDM material also retains strength and shock resistance even at high temperatures, which makes it great for the EDM process.
Hastelloy is a nickel-chromium-molybdenum wrought alloy that is considered the most versatile corrosion resistant alloy available. This alloy is resistant to the formation of grain boundary precipitates in the weld heat-affected zone, thus making it highly suitable for the EDM process.
Conductive materials for EDM such as titanium have a lower specific gravity, which means that it can be cut faster than other metals. Titanium is one of the most requested materials for wire EDM. Titanium is most commonly found in the medical and aircraft fields because of its strength, resistance and durability.
Kovar is a nickel alloy that hardens rapidly and has a thermal expansion similar to glass, so it is the ideal material for the EDM process. Kovar has been used for making hermetic seals with the harder Pyrex glasses and ceramic materials. It is also used in applications such as power tubes, microwave tubes, transistors and diodes.