Hardness alone does not establish an electrical-discharge path.
Identify the required physical property
Makino describes EDM as spark erosion of electrically conductive materials, including hard workpieces. Hardness and electrical conduction therefore answer different eligibility questions. Primary reference: Makino process explanation.
Review fictional property cards
Imagine three unnamed material cards. A has high measured hardness and documented conductivity. B has equally high hardness but documented insulating behavior. C has lower hardness and documented conductivity.
Hardness alone would group A and B together, while the stated EDM electrical requirement distinguishes them. C is not ruled out merely because it is softer. These cards are conceptual categories, not a ranked alloy list, a machine-capability trial or permission to process a particular material.
Request the evidence relevant to the route
Keep material identity, relevant electrical behavior and intended geometry in separate fields. Check that a coating or composite construction does not make a bulk-property label an incomplete description of the actual machining path.
Ask the supplier how the chosen EDM arrangement and actual material support the desired feature. Conductivity does not establish achievable accuracy, removal rate or surface integrity by itself. This worksheet prevents a mechanically difficult material from being declared EDM-compatible solely because it is hard, while preserving the other evidence needed before the process is compared with conventional cutting.
Customer Questions
Does hardness prove EDM eligibility?
Conductivity also matters.
Is a softer conductive material automatically excluded?
Hardness alone does not exclude it.
Does conductivity establish final accuracy?
Actual process and feature evidence remain necessary.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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