Wire EDM

Wire EDM cuts electrically conductive materials with a moving wire electrode for ultra-precise, burr-free profiles and sharp internal features, independent of material hardness.

Overview

Wire EDM (wirecut EDM) is a non-contact cutting process that erodes conductive material with controlled electrical discharges between a thin wire and the workpiece in deionized water. It excels at 2D profiles and through-cuts with very tight tolerances, sharp internal corners (limited by wire diameter), and excellent edge quality—especially in hardened steels and carbides where conventional cutting tools struggle.

Choose wire EDM for precision blanks, tooling, and intricate contours where distortion, burrs, or tool forces are unacceptable. It’s common for low to medium volumes and high-value parts where setup and cycle time are justified by accuracy.

Tradeoffs: it only works on electrically conductive materials; it’s generally slower than milling for simple shapes; and it’s primarily a through-cut process (true blind pockets require other EDM methods). A small recast/heat-affected layer can exist and may need skim cuts or secondary finishing for fatigue-critical surfaces.

Common Materials

  • A2 tool steel
  • D2 tool steel
  • 17-4 PH stainless steel
  • Titanium Ti-6Al-4V
  • Inconel 718
  • Tungsten carbide

Tolerances

±0.0005"

Applications

  • Progressive die inserts and punches
  • Injection mold inserts and shutoffs
  • Keyways and internal splines in hardened parts
  • Precision shims, gauges, and calibration artifacts
  • Carbide wear plates and tooling blanks
  • Medical instrument profiles and slots

When to Choose Wire EDM

Wire EDM fits parts needing very accurate through-cut profiles, sharp internal features, and clean edges with minimal mechanical distortion. It’s a strong choice for hardened or difficult-to-machine conductive materials and for tooling-quality parts in low to medium volumes. It’s most economical when the geometry is complex enough that milling setups, tool wear, or burr control become costly.

vs Sinker EDM

Choose wire EDM when the feature can be produced as a through-cut profile or when you need extremely accurate 2D contours with minimal polishing. Sinker EDM is better for blind cavities, 3D shapes, and textured surfaces where a wire cannot pass through the part.

vs EDM Drilling

Choose wire EDM for finished profiles, slots, and contours with tight positional accuracy and edge quality. EDM drilling is typically used to create small start holes, deep small-diameter holes, or cooling holes quickly, then wire EDM can follow to cut the final shape.

vs CNC milling

Choose wire EDM when the material is hardened (or will be heat-treated) and you need burr-free edges, minimal distortion, or thin-wall features that would deflect under cutting forces. Milling is usually faster and cheaper for simple geometries and for non-through features like pockets and faces.

vs Laser cutting

Choose wire EDM when tolerance, edge squareness, and metallurgy matter—especially on thick sections or hardened steels where laser kerf taper and heat effects become problems. Laser is often faster for thin sheet and looser tolerances, but typically won’t match wire EDM accuracy and finish.

Design Considerations

  • Specify the smallest internal corner radius based on wire diameter (typical wire 0.010"–0.012"; smaller wire increases cost and time).
  • Include a start hole location/size or allow the shop to add a start hole in a non-critical area for closed profiles.
  • Call out which surfaces are cut faces and identify any cosmetic or sealing edges that require skim cuts or specific surface finish.
  • Avoid unnecessary tight tolerances on long perimeters; tolerance drives skim passes, temperature control, and inspection time.
  • Minimize thick-to-thin transitions near the cut path to reduce taper risk and improve straightness on tall parts.
  • Provide material condition (annealed vs hardened) and any post-EDM requirements (stress relief, polishing, coating) so the shop can plan recast-layer control.