The graphite industry is constantly striving to produce higher quality grades. Graphite materials have continued to evolve along with the other aspects of the EDM industry,

but at a less dramatic pace. Advancements have been made in the microstructure of the graphite materials, as this is the key to performance.

Coarse graphites with particle sizes over 100 microns have never been suitable as an electrode material. During the last decade, medium grades with a particles size between 21-100 microns have all but disappeared from the market as an EDM material. In the last few years many of the low-end grades within the fine classification (11-20 micron particle size materials) also have disappeared. The superfine classification (6-10 particle size) materials have remained stable. Some of the manufacturers of these materials allow their graphite grades to be sold as house brands, which can be confusing to the end user.

Confusion occurs when consumable distributors change the names of their house brands, but still use the same material or change the material, but keep the same name for the house brand. The same grade may be offered under many house brand names. The ultrafine classification (1-5 micron particle size) is where most of the real development efforts are targeted. Many of the plastic consumer products require molds with fine detail and finishes that can easily be achieved with ultrafine materials. Materials in this classification are very difficult and expensive to make and it is even more difficult to produce consistent material batch after batch and year after year.

There are very few grades in the angstrofine classification (< 1 micron particle size). The grades are available in small blocks to control the uniformity of the graphite. These grades are the most expensive to produce and have limited use. Generally, they are used for fine detailed engraving electrodes and small featured electrodes that produce very high surface finishes without the use of powder additives when polishing of cavities is not possible.

The lower end graphite grades are slowly disappearing from the market as EDM applications change. Large cavity mold work without fine detail and forging dies can easily be done by high-speed milling thus reducing the need for grades in the fine classification. At the same time intricate detailed cavity work requires graphite with small particle sizes, uniform microstructure and high strengths to produce complex, small-featured cavities.