How does graphite particle size affect EDM machining performance?

EDM graphite is graded by particle grain diameter.

Sub-micron grades with grains under 1 µm offer the highest density, best corner retention, lowest wear, and finest surface finish for high-precision dies.

Premium grades with grains between 1 µm and 5 µm represent the industry standard for tight-tolerance mold-making.

High-performance grades with grains between 10 µm and 20 µm serve medium-to-large dies.

General-purpose grades with grains above 20 µm offer low cost for roughing burns, but generate heavy dielectric swarf.