Reconsidering Copper Electrodes

Although most U.S. moldmakers machine EDM electrodes from graphite, one shop reports that copper creates less of a mess, reduces flaws resulting from DC arcing, and imparts a better surface finish.


Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

An example of a copper electrode at B A Die Mold.

B A Die Mold first experimented with machining EDM electrodes from copper rather than graphite in the early 2000s, and the company hasn’t looked back since. Although that makes the shop unusual compared to most U.S. mold manufacturers, copper is more popular among their counterparts in Europe. At least, that’s what Tom Hipp, national high speed mill manager and turn-key projects manager at Sodick, told me during a visit to that company’s Chicago-area tech center a few months back.

The fact that B A Die Mold’s switch to copper was inspired directly by lessons learned across the pond bears out Mr. Hipp’s claim. During a visit to Switzerland, company founder Alan Petrucci was struck by the cleanliness of the shops he saw there. The fine, black dust covering every surface, employees taking precautions to avoid breathing the stuff in, the venting and other peripherals associated with dust-collection systems on machine tools—the Swiss would have none of it. “Graphite is a dirty word in German,” Mr. Petrucci notes.

Cleanliness isn’t the only advantage of copper. Compared to graphite, the material tends to impart a better finish on critical mold surfaces, he says. That means less polishing, and by extension, a more efficient process and a faster delivery. He adds that making the switch has reduced the need for welding and rework resulting from DC arcing, a phenomenon that can create pits or holes in the part surface. And although the material is more expensive, copper can be sold after the electrode wears, whereas graphite typically goes into the dumpster.

Mr. Petrucci emphasizes that both materials have advantages and disadvantages, and the shop does use graphite electrodes in some cases. That said, the company’s experience demonstrates that copper may be well-worth a second look for shops seeking new efficiencies.

Meanwhile, the use of graphite electrodes is far from the only change the company has made since the early 2000s. This article offers plenty of additional detail on B A Die Mold's evolution during the past 15 years, including the adoption of new technology, cross-training efforts, and the spinning of its own idea into a new product line that eases the manufacture of rotating-core molds.