Definition
Why EDM is a manufacturability decision, not just a process choice
A drawing rarely specifies EDM directly. It specifies a hardened material or a sharp internal corner that a rotating cutting tool cannot reach, and EDM is what a manufacturability judgment falls back on once milling and turning are ruled out. Wire EDM and sinker EDM are the two practical branches of that fallback, distinguished by whether the geometry is an open profile a wire can thread through or a closed cavity that needs a shaped electrode. See wire EDM for the profile-cutting branch.
Frequently asked questions
Why use EDM instead of milling?
Because EDM handles very hard conductive materials and fine or sharp geometry, such as internal corners, that a rotating cutting tool cannot reach or cut efficiently.
Are there different types of EDM?
Yes, wire EDM cuts a profile with a thin wire, sinker EDM shapes a cavity with a formed electrode.
Does EDM leave a different surface than milling?
Yes, EDM produces a distinct recast layer and finish that sometimes needs its own inspection note.
Notes & references
- Kunieda, M., Lauwers, B., Rajurkar, K.P. & Schumacher, B.M. (2005). Advancing EDM through fundamental insight into the process. CIRP Annals – Manufacturing Technology, 54(2), 64–87. https://doi.org/10.1016/S0007-8506(07)60020-1 The keynote review most widely cited for consolidating the physics and process fundamentals of EDM — used here as the manufacturing-science grounding for this definition.