What are the Advantages of Graphite Electrodes?

Graphite electrode refers to a resistance electrode made of petroleum coke and pitch coke as aggregates and coal pitch as binder. It is made by calcining raw materials, crushing and grinding, batching, kneading, shaping, roasting, impregnation, graphitization and mechanical processing. High-temperature graphite conductive materials are called artificial graphite electrodes (graphite electrodes for short) to distinguish them from natural graphite electrodes prepared from natural graphite.

SINOMETAL Product Page

Heyuan New Material Technology Co., Ltd - Graphite Electrode Direct Plant

What are the advantages of graphite electrodes?

(1) The increasing complexity of mold geometries and the diversification of product applications have led to increasingly higher requirements for the discharge accuracy of spark machines. The advantages of graphite electrodes are easier processing, high discharge machining removal rate, and low graphite loss. Therefore, some customers of Qunji EDM machines gave up copper electrodes and switched to graphite electrodes. In addition, some special-shaped electrodes cannot be made of copper, but graphite is easier to shape, and copper electrodes are heavier and are not suitable for processing large electrodes. These factors have led some Qunji spark machine customers to choose to use graphite electrodes.

(2) The design of graphite electrodes is different from traditional copper electrodes. Many mold factories usually have different roughing and finishing machining allowances for copper electrodes, while graphite electrodes use almost the same machining allowance, thereby reducing the amount of CAD/CAM and machining. This reason alone is enough to improve the accuracy of the mold cavity to a great extent.

Are you interested in learning more about graphite electrode manufacturer? Contact us today to secure an expert consultation!

(3) Graphite electrodes are easier to process and the processing speed is significantly faster than copper electrodes. For example, the milling process is used to process graphite, which is 2 to 3 times faster than other metal processing, and does not require additional manual processing, while copper electrodes require manual polishing. Similarly, if a high-speed graphite machining center is used to manufacture electrodes, it will be faster and more efficient, and there will be no dust problems. During these machining processes, selecting tools and graphite with appropriate hardness can reduce tool wear and copper electrode breakage. If we specifically compare the grinding time of graphite electrodes and copper electrodes, graphite electrodes are 67% faster than copper electrodes. In general electrical discharge machining, machining with graphite electrodes is 58% faster than machining with copper electrodes. In this way, processing time is significantly reduced and manufacturing costs are also reduced.

&#; Contact: Ms Anna Xu (Business Development Sales Manager)

&#; Mob/: +86

&#; Wechat: +86

Graphite has many advantages that have made it the material most widely used for EDM electrodes.

• It is easy to machine.
• It is very resistant to thermal shock.
• It has a low coefficient of thermal expansion (3 times lower than copper) which guarantees stability of electrode geometry during electro discharge machining.
• It is available in large blocks.
• It does not melt, but goes directly from the solid state to the gaseous at 3,400°C,
• which reduces wear.
• Its density is 5 times lower than that of copper, which results in lighter electrodes.
• It provides a higher metal removal rate than copper with less wear.
• It has the unique characteristic that the wear ratio tends to decrease as the peak current increases.

More About Graphite
Graphite used for EDM machining is an isotropic material with a grain size ranging from a few microns to about 20 microns. In the 's, improvements made by graphite manufacturers (isotropic properties, consistent quality, large size billets) combined with the emergence of EDM machines equipped with iso-plus generators, allowed graphite to become the most commonly used material for EDM machining electrodes.

Three separate groups of graphite can be defined:
1. Large grain graphite (about 20 µm) with low densities (1.76 g/cm3)
2. Fine grain graphite (~10 µm) of high density (1.82 g/cm3)
3. Very fine grain graphite (~4 µm) with densities greater than 1.86 g/dm3

Larger grained graphite is used for machining in roughing modes while fine grain graphites produce the best surface finishes for finishing operations. As graphite has become more affordable, EDM machining shops will often inventory two or even three types or grades of graphite. A less expensive large grained graphite for the roughing operation; followed by a finer grained graphite for finishing or a combination of both roughing and finishing performance; and possibly an expensive very fine grained graphite for fine finishing and precision operations.

Why Graphite?
Graphite has several advantages over other materials. It is resistant to thermal shock. It is the only material in which mechanical properties increase with temperature. It has a low CTE for geometrical stability. It is easily machined. It does not melt but sublimes at very high temperature (3,400ºC), and finally, its density is lower (five times less than copper) which means lighter electrodes. Graphite removes material better than copper or copper-tungsten while wearing slower. The wear rate tends to diminish as the discharge increases, unlike copper, whose wear increases at higher currents. Therefore, graphite is suited for the machining of large electrodes since working with a high current intensity provides decreased roughing time.

Although graphite is prone to abnormal discharge, this can be eliminated through quality flushing, and lowering the intensity of discharge during negative polarity machining. However, as a result of this tradeoff, machining tungsten carbides is more difficult than with copper-tungsten electrodes. Also, since graphite is a ceramic, it is sensitive to mechanical shock, and consequently must be handled and machined with care.

Comparing Graphite Grades
It is not advisable to compare a grade of graphite to another just by looking at physical properties without also performance testing the graphite in actual EDM operations. However, the following is a list of physical properties of graphite that exhibit some effect on performance in EDM operations.

If you want to learn more, please visit our website graphite electrodes for sale.

• apparent density
• average grain size
• electrical resistivity
• flexural strength
• hardness