EDM Sinking (also known as die‑sinking EDM, sinker EDM, ram EDM, cavity EDM, or plunge EDM) is a non‑traditional machining process that uses electrical discharges — electric sparks — to remove material from a conductive workpiece. A custom‑shaped electrode, typically made of graphite or copper, is slowly plunged into the workpiece submerged in dielectric fluid. As the electrode approaches the workpiece, sparks jump across the narrow gap, generating intense localized heat exceeding 8000°C, which melts and vaporizes tiny portions of the material. The eroded material is flushed away by the circulating dielectric, leaving a cavity that precisely mirrors the shape of the electrode.

Unlike conventional cutting methods that can induce mechanical stress and alter material properties, EDM sinking is a non‑contact process. This makes it the definitive final step in precision mold manufacturing — especially for creating intricate blind cavities, deep ribs, sharp internal corners, and complex geometries in hardened materials that would be extremely difficult or impossible to machine with traditional tools

Product Features

• Machining after hardening：Fully hardened steel (up to 62 HRC) can be finish-machined without distortion, eliminating heat-treatment risks and scrap loss.
• Complex 3D geometries：Capable of creating blind cavities, narrow slots, fine grooves, and sharp internal corners that are difficult for milling.
• Exceptional precision：Dimensional tolerances as low as ±0.002 mm and surface roughness Ra ≤ 0.6 μm, achievable to optical polish quality.
• No mechanical stress：Non-contact process – no burrs, tool deflection, or residual stress – ideal for thin walls and fragile structures.
• Material & electrode strategy：Works with all conductive materials (pre-hardened steel, carbide, copper alloys, etc.). Uses roughing, semi-finishing, and finishing electrodes in sequence to ensure surface quality and consistency across multi-cavity production.

Technical Parameters