EDM Graphite

EDM Graphite

EDM graphite is used in electric discharge machining, which serves an alternative to metal cutting and removes metal via burning or erosion. Graphite is a vital component to EDM because they cause less wear on EDM electrodes, and removes metal quickly. The electrodes are what are used to tool the desired shape and carry electric current. Graphite is easy to machine, exhibits great temperature resistance without burning, chemically changing or melting, and is inexpensive to use. It may also be redressed over and over again. As an alternative to copper, EDM graphite is needed wherever electrical discharge machines are used, including the food, beverage, automotive, metal stamping and extruding, defense, electronics, aerospace and medical industries. Organized storage of EDM graphite is very important, because using the wrong type will waste time and money. For example, choosing ultrafine graphite for roughing a large cavity will waste money and produces the wrong results. The only drawback to EDM graphite is the mess it creates while machining-it generates an excessive amount of dust. Modern EDMs are often equipped with negative pressure shrouds, which remove almost all the dust.

There are 5 main measured physical properties of EDM graphite. The first is particle size. The graphite powder that is used to make EDM tools has varying grades of fineness. Smaller particles result in a smoother surface finish, while large particles offer a higher MRR (metal removal rate). Today, graphite powder particles are anywhere between 1 to 20 m. Next flexural strength is measured. Tighter bonds between particles result in greater strength, which means good machinability and reduced erosion during the discharge phase. The apparent density of graphite measures how much carbon there is in terms of volume; the higher the density, the lower the wear rate. Hardness is measured in shores, and good, strong EDM graphite is between 60 and 80 shore, and exhibits no cracking or chipping during machining. Finally, electrical resistivity is measured. Lower usually means no overheating. Particle size is measured using a scale with 4 options. The most advanced and fine type of EDM graphite is called angstrofine, and is used when fine detail and a smooth finish is required. It has particles smaller than 1 micron. Next, ultrafine particles are between 1 and 5 microns, and are the most common. Superfine particles are between 6 and 10 microns, and are used roughing in cavities with larger detail, while fine graphite, who's particles are between 11 and 20 microns, are strictly used for roughing large cavities.