Most mold and die repair involves using a laser welder or a micro welder. Once it is welded, the mold needs to be re-machined, or hand-worked back to it’s original state. This is where the EDM comes in, often as the only practical method or remachining the hardened steel.
The laser welder is a marvel to behold. What once was only possible for the most skilled micro tig welder can now be done with a minimal amount of practice. The operator, who is usually also a toolmaker, can lay a bead at the bottom of an injection mold cavity rib, without any sink or distortion. Or maybe you need a little dot on the tip of a mold component or stamping die punch, no problem.