Electrical Discharge Machining And Injection Mold Making

Electrical discharge machining, or EDM, is such an integral part of injection mold making that they are inseparable. In the eons ago, before EDM, injection molds were milled, filed, turned, ground and handworked to obtain the same results as today, with the newer technology.
The fits and finishes are much better, as are the designs, thanks to this amazing process. Many of the molds made today would simply be impossible if done the old way. With computers playing such a critical role in the design and manufacture, parts have become very complex and expensive.
For example: rather than make many small inserts to create a plastic part, now there may be only one steel part with all the details machined. This makes the process simpler, but also more risky in the event of a mistake. Now you are throwing away a very expensive component instead of a small part of that component.
Then there is the wire EDM! This remarkable tool is like an electrical bandsaw that cuts to extreme accuracies, regardless of the steel hardness or type. Hardened tool steel is extremely difficult to machine, but the WEDM makes it look easy!
Randy Hough writes about electrical discharge machining.