ECM Drilling Applications

Shaped or round holes including turbulators can be drilled in difficult-to-machine conductive materials with depth to diameter ratios up to 300:1. Typical use is to drill slots and cooling holes in aerofoil shapes such as turbine blades.

The process produces no heat affected zones or stress in the material. The hole surface roughness ranges from 32 to 125 micro-inches (Ra 0.8 to 3.2µm). The same tooling can produce different hole sizes within limits by varying the process parameters such as feedrate and applied voltage.

The number of holes drilled per machine stroke is limited only by space requirements for tooling fixtures within the work enclosures. Hole diameters ranging from 0.020 to 0.250 inch (0.5 to 6.4mm) can easily be accommodated.

Drilling feedrates are typically 0.080 inch/min (2.0 mm/min) but can be as high as 0.150 inch/min (3.8mm/min) depending on the particular application. The electrolyte is chosen on the basis of the workpiece material and is generally either 10 to 20% Sulphuric Acid (H₂SO₄) or 15 to 30% Nitric Acid (HNC₃).