Sinker EDM (Die-Sinking)

Overview

A sinker EDM removes metal without ever touching it. A shaped electrode and the workpiece are both submerged in dielectric oil and wired to a pulse power supply; the electrode is fed down to within a few microns of the work, and thousands of sparks a second jump the gap. Each spark vaporises a tiny crater of metal, and the eroded form of the electrode is reproduced, in reverse, in the work. Because there is no cutting force, the process machines hardened tool steel, carbide and exotic alloys that would defeat a milling cutter, and it cuts sharp internal corners and blind cavities a rotating tool cannot reach. That is why it is the standard way to sink injection-mould and forging-die cavities.

The machine is built around a rigid C-Frame & Column. The work sits on the X-Y Cross Table to position it under the electrode, while the Z Ram / Quill plunges the electrode down. Every axis carries a Glass Scale so the control measures the slide itself, not the ball screw, holding position to a few microns through long burns.

How it works

The electrode clamps into the Electrode Holder Head at the foot of the ram, squared to the work and fed by flush nozzles. The spark comes from the Pulse Generator, which charges across the gap, fires a controlled discharge through its MOSFET Output Bank, then quenches it, repeating in microseconds. Cutting current, on-time and off-time set the trade between fast roughing and a fine Discharge Capacitor-fed finishing spark.

The gap must stay clean or the sparks degrade into a short. The Dielectric System pumps filtered, chilled oil through the Flush Nozzles to wash eroded particles out of the gap, and the whole cut runs submerged inside the Work Tank. The Adaptive Controller watches the Gap Sensor and constantly trims the Z servo: it advances while the gap sparks cleanly and retracts to flush the moment voltage signals a short. The operator sets the electrode, dials in the finish, and lets the adaptive loop burn the cavity to depth.