Wire electrical discharge machining cuts metal with sparks rather than with an edge. The wire never touches the work in the mechanical sense. It is held under tension and fed through the part while a controlled electrical discharge erodes material in a narrow kerf, with the part flushed or submerged so the debris leaves the gap. Because there is no cutting force, hardness barely matters and thin sections do not get pushed out of shape.
That last point is why the process keeps turning up in fabrication shops that mostly weld, rather than only in toolrooms where it was first developed.
A milling cutter removes material by force, and force is exactly what a thin-wall tube or a delicate fabricated bracket has least of. A wire produces no side load, so it can cut a slot in a part that would deflect under a cutter, and it can cut a profile into material that has already been hardened without softening it first.
The trade is speed and geometry. EDM is a slow way to remove a lot of material, and it cuts through-thickness profiles rather than pockets, so it is chosen for accuracy rather than output.
It is also indifferent to how the material behaves under a cutter. Hardened stainless, a tough titanium section and a soft aluminium plate are all cut the same way, provided the settings are adjusted.
In exhaust, intake and general metalwork, the wire is most useful on flat profiles with tight tolerance: flange plates with port openings, bolt patterns, separator plates, and small brackets where the hole positions decide whether the assembly lines up. It is also the practical answer for cutting a hardened or awkward part that cannot be machined conventionally without softening it.
The sort of work it serves usually ends up in an assembly rather than standing alone, which is why the cut blanks feed into TIG welded parts rather than replacing them.
Because the material is eroded rather than sheared, the wire leaves a surface that has been through a very local thermal cycle. The recast layer is thin, but it is different from the parent metal, and on parts that will be welded or cycled that layer matters. The usual answer is a finishing pass at lower energy, which removes the roughest of the first cut and leaves a cleaner surface.
Heat treatment is not the concern it would be with a torch, because the discharge is confined to the kerf. A hardened part stays hard, which is often the whole reason the wire was chosen in the first place.
Wire EDM cuts a straight-sided profile through the work. It cannot machine a blind pocket, it cannot turn a cone in the round, and it is not a way to cut a long tube down its axis. For those jobs a saw, a lathe or a mill is the right tool, and no amount of patience with a wire will substitute.
It is also a process that needs a start path. A fully closed internal profile needs a hole drilled so the wire can be threaded through, which means the process has to be planned with that hole in mind rather than added later.
Taper is possible on some machines, but it is limited, and a designer who assumes a deep draft can be produced by the wire will be disappointed.
A part going to the wire should arrive flat and clean, with the material identified and a start hole where one is needed. Scale, rust or heavy oxide on the surface can affect the cut, and a part that has been cut nearby by another thermal process may carry a harder edge that should be dressed before the wire runs.
Fixturing is simple but not trivial. The part has to be held flat and square so the cut is through the intended thickness, and on thin plate the clamping must not bow the material out of plane.
Once a path is proven, the wire is one of the more repeatable processes available: the same path, the same offset, the same result on part two and on part two hundred. That is why it suits parts where hole positions must match a mating component, and why a first-article check is enough to release a batch.
The repeatability still depends on the setup. A different clamping position, a different wire diameter or a fresh offset without a test cut can all move the result, so the discipline is in the preparation rather than in the cut itself.
The points below decide whether a profile part is straightforward or a source of rework.
Profiles cut this way usually end up in a welded assembly. Our TIG welded parts show where they go, and the same cut blanks feed our fabricated components and our formed tube runs. Smaller fabricated parts take the same path, the custom work page covers how such jobs are specified, and our material pages explain how titanium, stainless and aluminium each respond to a cut edge.
