I use the edm for a couple of reasons. First is it is HIGHLY accurate. It is slow, but the finish and accuracy is the tradeoff. Second is it's ability to cut complex profiles with one setup. If I used a machining center, I would have several tool changes and expensive cutters, and probably more than a couple of setup changes. There are a lot of potential problems and loss of accuracy issues. The accuracy of the EDM allows me to cut the separate parts that will fit together near perfectly with minimal polishing of their mating surfaces.