ences between the two. First, while current is passed between an electrode and workpiece in both methods, in ECM there is no spark. Rather, ECM uses a conductive electrolyte, while EDM uses a dielectric. Second, ECM has virtually no tool wear. Third, in ECM there is no HAZ (heat-affected zone) like there is in EDM. This results in a part with no burrs, and the ECM process has potential for exceptional surface finishes even on extremely hard-to-machine materials, such as those found in firearms manufacturing. “Firearms take advantage of another aspect of ECM that has significant merit: namely, the ability to produce contours and pockets deep inside parts that would otherwise be difficult or even impossible to manufacture with conventional chip-cutting methods,” he says. “The machining force in ECM is just the pressure of the electrolyte, which allows ECM to produce features like
high-aspect ratio holes in conductive materials of any hardness.” Furthermore, as material is dissolved in the electrolyte, it is evacuated from the work area, and the tool imprints its geometry upon the workpiece. ECM can produce tight contours. For example, the grooves in a rifle barrel can be cut to a depth of ± 2.5 micrometers. “All in all, ECM rifling is best suited for high-production runs with minimal variation, and here again ECM is showing substantial value,” Popecki says. “In competitive shooting, where match-grade barrels are the minimum standard, and gain twist and special groove profiles are prominent, the effectiveness of the ECM process is distinguished. On ECM machines today, a hunting rifle barrel and a military cannon barrel can potentially be rifled on the same machine. Caliber changeovers can be done in minutes.” (emag.com)
Another advantage of ECM is the creation of parts that contain no burrs, which require further work.
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