According to this company, a good way to decide whether your parts need to be made using electrical discharge machining (EDM) is to look at what it calls the "Three Point Rule": Can't cut it - Can't shape it - Can't reach it. When any of the conditions apply to your job, it is a possible candidate for EDM. When two of these conditions apply, you should consider EDM for your application. But when all three apply, EDM is the solution.
ABET Industries Corp, 111 N Kemman Ave, La Grange, IL 60526, (708) 482-8282, production-edm.com