Mitsubishi Electric EA12V

Mitsubishi's VS (Variable Speed) discharge control monitors the inter-electrode gap voltage continuously and detects transitions from stable spark erosion toward unstable arc discharge. When arc risk is detected, the system reduces pulse energy or interrupts the discharge cycle before arcing occurs. Arcing causes localized electrode and workpiece damage, surface pitting, and potentially electrode breakage — the VS system significantly reduces these events during long burns.

Graphite is the most commonly used electrode material with the EA12V for die and mold applications. It is easily machined to complex shapes using CNC milling and produces good wear ratios with Mitsubishi's VS generator on steel and hardened tool steel. Copper electrodes produce lower wear ratio on very fine finishing conditions. Copper-tungsten is used for fine features in carbide. The V400's condition database provides starting parameters for each electrode/workpiece combination.

Yes. Sinker EDM is a non-contact process that erodes material by spark discharge regardless of workpiece hardness. Hardened H13, D2, P20, and stainless steel are routinely processed on the EA12V. The material must be electrically conductive — EDM cannot process ceramics or plastics. Hardened steel at HRC 60 is processed as readily as annealed steel with appropriate generator settings.

The EA12V's optional AEC (Automatic Electrode Changer) holds 6 electrodes. For cavity sequences requiring roughing, semi-finishing, and finishing electrodes, the 6-position magazine typically accommodates a complete electrode set for one or two cavity programs. For more complex programs requiring many electrodes, the operator can manually reload the AEC magazine between sequence segments.

On a standard injection mold insert cavity in hardened P20 or H13, the EA12V achieves approximately Ra 3.2 µm on rough cut, Ra 0.8–1.0 µm on semi-finish, and Ra 0.2 µm on final finishing pass with appropriate orbit and copper electrode. For optical-quality surfaces (Ra 0.05–0.1 µm), the EA12V is not the right choice — the EA28V or a higher-tier Sodick AL machine would be more appropriate.