Electrical Discharge Machining and Mold Repair
Every injection mold eventually needs to be repaired, and the electrical discharge machine, or EDM, is very often the machine tool of choice to do the repair.
Some shops have a dedicated repair department to handle the demand from the production area, others just fit the repairs in as needed. The EDM department is typically quite busy and the machines are running almost 24/7, therefore mold repair tends to take a back seat to the new tooling.
This always causes a conflict because the production needs the mold fixed right now, but the EDM is too busy! If it can be squeezed in, fine, but another solution is to keep an older machine on hand just for repairs. Sometimes this could even be a manual machine, instead of a CNC.
Because most electrodes are machined on a high speed machining center and held on precision tooling, such as Erowa or System 3R, it is relatively easy to make new electrodes to do the repair. In the event that the old electrodes are usuable and in storage, great!
Once the damaged or worn mold is laser or micro welded, then EDM’d, it must be hand polished and refitted into the mold to be exactly like the original. This is somewhat of an art and requires considerable skill, knowing what to do and what not to do takes experience and understanding of what is important.
Randy Hough has a website, http://completeedm.com, that talks about electrical discharge machine
