Wire electrical discharge machining removes material with controlled electrical discharges between a thin wire electrode and the workpiece. Because the process does not rely on conventional cutting force, it is valuable for hard materials, delicate sections and profiles that are difficult to reach with a milling cutter.
This Wire EDM machining guide outlines when the process is appropriate, what limitations should be considered and which drawing details help a supplier plan the work correctly.
The workpiece and wire are separated by a small controlled gap in dielectric fluid. Electrical discharges erode tiny amounts of material while the machine guides the wire along the programmed path. The wire is continuously fed, so a fresh electrode surface enters the cutting zone.
The material must be electrically conductive. Tool steels, stainless steels, copper alloys, aluminum and many conductive hard alloys can be processed, while ordinary plastics, ceramics and other nonconductive materials cannot be cut by standard Wire EDM.
For a closed internal opening, the wire must first pass through a start hole. That hole may be drilled conventionally or produced by a small-hole EDM process. Its position, diameter and relationship to the finished contour should be considered in the manufacturing plan.
An open external profile can often be approached from the edge. However, the cut-off section must remain controlled so that it does not move, trap the wire or damage the finished surface at the end of the cut.
The programmed path compensates for wire diameter and the discharge gap. Together they determine the effective kerf. Internal corners cannot be mathematically sharp; their minimum radius depends on the chosen wire and process conditions.
Wire EDM can also cut controlled tapers on suitable geometry. If the upper and lower profiles differ, provide both contours and identify the reference height. Large tapers, thick workpieces and abrupt profile changes may require additional process review.
A first cut removes the main material. One or more skim cuts can then refine size and surface condition with lower discharge energy. Additional passes increase machine time, so tolerance and finish should match the real function of the part.
Accuracy is influenced by workpiece thickness, flushing, thermal stability, wire condition, feature geometry and how the component is supported. A tight tolerance on one functional profile is different from applying the same tolerance to every cut edge.
Although cutting force is low, the electrical process creates a thin thermally affected surface layer. The importance of that layer depends on the material and application. Critical tooling, fatigue-sensitive components or special surfaces may require a defined skim-cut strategy, polishing or another finishing operation.
Heat treatment can also release stress and move the blank. Discuss whether rough machining, stress relief, hardening and final Wire EDM should occur in a specific order.
CNC milling is often efficient for open pockets, faces and accessible three-dimensional features. Wire EDM becomes attractive when the material is conductive and hard, the profile is through-cut, internal radii are small or cutting force must be minimized. Many components use both processes.
It can process many metals and conductive alloys, but conductivity, thickness, heat treatment and application requirements should be reviewed before selecting the process.
A closed internal contour normally requires a start hole so the wire can be threaded through the workpiece.
Provide the CAD profile, drawing, material, thickness, heat treatment, quantity, tolerance and surface requirement. Balford can review the project against its Wire EDM service.
Have a precision profile to manufacture? Send the drawing to Balford for process review.