EDM Drilling

EDM drilling produces very small, deep, accurate holes in hard, conductive materials using electrical discharges instead of mechanical cutting, with minimal tool pressure and no chips.

Overview

EDM drilling (small hole EDM, hole popper, fast hole EDM) creates small, precise holes in any electrically conductive material by eroding metal with rapid electrical discharges. Electrodes are typically thin copper or brass tubes, flushed with dielectric fluid to cut deep, straight holes without mechanical load or chip evacuation issues.

Use EDM drilling when you need tiny diameters, high aspect ratios, or holes in hardened steels, carbides, or superalloys that would destroy conventional drills. It excels at start holes for wire EDM, cooling holes, and features that must pass through hard coatings or heat-treated sections. Expect slower cycle times than standard drilling, a heat-affected “recast” layer, and rougher walls than precision boring. Costs stay reasonable for low to medium volumes and high-value parts, but cycle time rises quickly as you push for extreme depth, tight tolerances, or many holes.

Common Materials

  • Tool steel H13
  • Stainless steel 17-4PH
  • Inconel 718
  • Titanium Ti-6Al-4V
  • Carbide
  • Copper alloys

Tolerances

±0.001" to ±0.005" on hole diameter, depending on size, depth, and material

Applications

  • Wire EDM start holes
  • Turbine blade cooling holes
  • Fuel injector and spray nozzles
  • Aerospace engine components
  • Extrusion and drawing dies
  • Medical instruments and implants

When to Choose EDM Drilling

Choose EDM drilling when you need small-diameter, high-aspect-ratio holes in conductive, often hardened materials where conventional drilling is impractical or impossible. It suits low to medium volumes of high-value parts with demanding geometry, orientation, or access constraints. It’s especially effective for start holes, cooling passages, and through hard coatings or heat-treated zones.

vs Sinker EDM

Pick EDM drilling when the main requirement is producing small, deep, straight holes rather than complex 3D cavities or contours. It is faster and cheaper for simple cylindrical holes and start holes, especially in hardened or difficult materials. Use sinker EDM when you need shaped cavities, pockets, or forms that match a custom electrode profile.

vs Wire EDM

Choose EDM drilling when you only need a hole, or a start hole to enable later wire EDM profiling, particularly at very small diameters or extreme depths. Wire EDM is better for cutting out entire profiles and contours from plate or blocks, but it cannot initiate cuts without a pre-existing hole. EDM drilling is the go-to for quickly generating those initial start holes in tough materials.

vs CNC drilling

Select EDM drilling when mechanical drills cannot reliably produce the hole—due to very small diameter, extreme depth, hardened material, or intersecting features that would break tools. CNC drilling is faster and cheaper for larger, shallow, and moderate-depth holes in machinable materials. EDM drilling avoids tool deflection, chip packing, and high cutting forces, at the cost of slower cycle times.

vs Laser drilling

Use EDM drilling when you need highly accurate hole location, good straightness, and consistent diameter in conductive metals, especially at significant depths. Laser drilling can be faster for very high-volume fine holes or non-conductive materials but may bring more taper, thermal damage, and positional challenges. EDM drilling offers better control for critical aerospace, medical, and die applications where hole geometry matters.

Design Considerations

  • Specify hole diameter, depth, and positional tolerances clearly, and flag which are critical versus nice-to-have to control cycle time and cost
  • Avoid extreme aspect ratios above ~100:1 when possible; if required, discuss feasibility, acceptable taper, and straightness early with the shop
  • Provide a clear callout for through vs blind holes, start and exit surfaces, and any features the electrode must pass by for realistic fixturing
  • Group hole sizes and tolerances to minimize electrode changes and setups, especially when you have large hole count patterns
  • State whether recast layer removal, polishing, or secondary finishing is required; this significantly impacts process routing and price
  • If holes are for wire EDM start points, coordinate required wire size and preferred start hole diameter to avoid unnecessary extra passes