Die Tech avoids errors by inspecting electrodes prior to EDM
by Peter Zelinski, Senior Editor of Modern Machine Shop
Here, the EDM machine produces a simple hole. The combination of palletization and automatic EDM programming makes this approach more efficient than using a drill press.
Despite Die Tech & Engineering’s investment in machining centers, the shop still does plenty of sinker EDM work. Using EDM electrodes in a tight-lead-time process is “scary,” says president William Berry, because of the risk of error. An error in milling a complex graphite electrode, or in programming it at the machine, might not be detected until the EDM cycle has made a faulty part.
From Mr. Berry’s perspective, a coordinate measuring machine never made sense. Inspecting a part after machining adds no value, he says. Instead, when the shop finally did buy a CMM, it was for inspection before machining. Specifically, all EDM electrodes in the shop—hundreds of electrodes per week—now pass across a non-contact laser scanning head from Nikon Metrology, mounted on a Brown & Sharpe CMM.
Verifying electrode geometry in this way costs little lead time. Electrode CMM inspection programs are generated automatically. In fact, DTE has engineered its system to create EDM machine programs automatically as well, so every electrode is used correctly, without human error.
This electrode process, combined with palletization, has produced some counter-intuitive economies for the shop. I saw an example while visiting. In the photo seen here, a sinker EDM is used to produce a simple hole that, by any intuitive guess, ought to be drilled. However, Mr. Berry points out that the only savings drilling can offer would be cycle time. A human would still have to run the job on a drill press or machining center. By contrast, DTE’s EDM process is so seamless that there is no harm in letting an EDM machine produce the hole if an EDM machine happens to be available. Doing this frees employees to devote their attention to higher-value tasks.