Why does graphite machinability involve more than just ease of cutting?

Although all graphite grades machine easily, ease of cutting alone does not make a material suitable for an EDM electrode. The material must also possess sufficient mechanical strength to resist chipping and handling damage both in the shop and under the electrical stresses of the EDM process. High strength coupled with a small particle size allows the toolmaker to achieve tight dimensional tolerances and sharp minimum radii. Furthermore, material hardness directly impacts machinability, as excessively hard graphite grades are more vulnerable to edge chipping during cutting operations.