EDM

Electrical discharge machining removes metal by spark erosion.

A shaped electrode is brought close to the workpiece in a dielectric fluid. Controlled electrical discharges erode the metal in small increments. The electrode is usually fed along a programmed path to form the cavity or profile.

EDM is often done on hardened tool steels and other hard metals. It can also be done on aluminium and some copper alloys. Materials that are very hard or have complex shapes are harder to machine by conventional cutting.

Ask about the largest workpiece the machine can take and the tolerance held on depth and profile. Ask how many machines are available and the typical lead time for the job.