Why EDM exists

Conventional machining removes material by forcing a rotating cutter into the workpiece. If the workpiece is harder than the cutter, the cutter loses. This is why traditional machining struggles with hardened tool steels (above ~55 HRC), carbides, and precipitation-hardened alloys at full strength — the tools wear out before they can remove meaningful material.

EDM bypasses this entirely. Instead of mechanical force, it uses controlled electrical discharges between an electrode and the workpiece, submerged in dielectric fluid. Each spark removes a tiny amount of material (micron-scale) through localized melting and vaporization. The process doesn't care about hardness — A2 tool steel at 62 HRC cuts as easily as annealed 1018.

When to choose wire vs. sinker

Wire EDM uses a thin electrode wire (0.1–0.3 mm) that's fed continuously — like a CNC band saw, but electrical. Use it for profile cuts, through-features, and sharp internal corners with radius ≈ wire radius. Sinker EDM uses a shaped electrode (usually copper or graphite) that's plunged into the workpiece. Use it for blind cavities, complex 3D pockets, and internal features that aren't profile-based.

§ 01 / Equipment

Machines currently in operation.

Machine Capacity Spindle / Capability Qty Typical use
Sodick AQ400L wire EDM400 × 300 × 250 mmØ0.1–0.3 mm wire3Profile cuts, gears, tooling inserts
Sodick AQ327L wire EDM320 × 250 × 220 mmØ0.1–0.25 mm wire1Smaller parts, finer detail
Sodick AG60L die-sinker450 × 350 × 300 mmCopper/graphite electrodes13D cavities, blind pockets, molds
Makino EDAF2 die-sinker350 × 250 × 300 mmCopper/graphite electrodes1High-precision small cavities
§ 02 / Applications

Parts we make most often with this process.

CATEGORY · TOOLING

Mold & die inserts

Injection mold cavities, stamping die components, progressive die tooling. Usually D2, H13, or P20 tool steel, hardened and tempered before EDM.

CATEGORY · TOOLING

Punches & progressive dies

Sharp-cornered punches for progressive stamping dies. Wire EDM produces internal corners down to the wire radius (0.05 mm).

CATEGORY · AEROSPACE

Turbine components

Cooling holes in hot-section blades, complex internal passages in fuel nozzles. Hole-popping EDM variant for arrays of small holes.

CATEGORY · MEDICAL

Surgical jaws & scissors

Complex articulating geometries in 440C stainless. Wire EDM profiles cut before heat treatment; fine features sinker-cut after.

CATEGORY · METROLOGY

Precision gauges

Pin gauges, plug gauges, master rings. Wire EDM's straightness and accuracy suit gauge-quality production.

CATEGORY · COMPONENTS

Thin-wall shapes

Stator laminations, thin-wall bellows housings. Wire EDM can cut stacks of thin material without burring or distortion.

§ 03 / Design considerations

What to know before releasing a drawing.

01
Cycle times are slow — plan for it
EDM is slower than milling by 5–20×. A pocket that takes 10 minutes to mill might take 2 hours to sinker-EDM. This is why EDM is reserved for features milling can't handle — sharp corners, hardened material, extreme detail. Use it surgically, not comprehensively.
02
Wire EDM starter holes
Any internal profile that isn't open to an edge needs a starter hole (drilled or pre-cut). Design in a ~0.5 mm hole at an internal corner, or tell us to add one. The starter location usually shows as a small 'tab' or witness mark on the finished part.
03
Surface finish vs. speed
EDM surface finish is controlled by skim passes. A single rough pass leaves Ra ~3 μm; four progressively fine skim passes get you to Ra 0.4 μm. Each skim pass adds 30–50% to cycle time. Specify Ra only on surfaces that need it.
04
Recast layer consideration
EDM leaves a thin (3–15 μm) recast layer — melted and resolidified material. It can be slightly harder and more brittle than the base material. For fatigue-critical parts, specify 'recast layer removed' (by etching or additional fine skim passes). Standard practice leaves recast in place.
05
Electrode design for sinker EDM
For sinker EDM, the electrode is essentially the negative of your part. Complex geometries may require multiple electrodes (rough + finish). We design and produce electrodes in-house — this is included in the quote, but expect 2–4 days added to lead time for custom electrode production.

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