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EDM is the abbreviation for Electrical Discharge Machining.  It is one of the most essential processes in mold manufacturing, specifically used to machine areas that traditional cutting tools cannot reach.

Basic Principle

It uses the high temperature generated by electrical discharge to "burn away" metal bit by bit.

The tool electrode and the workpiece do not touch. Pulse discharges occur in a dielectric fluid, with instantaneous temperatures reaching 8000–12000°C. Local metal is melted and vaporized, then flushed away by the dielectric fluid. This process repeats thousands of times per second, gradually machining the desired shape.

Key point: The electrode and workpiece do not touch, and there is no cutting force, so very hard materials can be machined.

Two Main Types

1. Sinker EDM

A formed electrode is pressed downward to "burn" the corresponding shape. Used for deep cavities, narrow slots, sharp corners, and complex surfaces.

2. Wire EDM

A thin metal wire (0.1–0.3mm in diameter) cuts along a path like a saw. Used for punches, dies, and precision holes.

Advantages and Limitations

Advantages:

·Can machine hardened steel, carbide, and other ultra-hard materials

·No cutting force, suitable for thin-walled and easily deformed parts

·High precision: Sinker EDM can reach ±0.005mm, Wire EDM can reach ±0.002mm

·Can machine complex shapes such as deep slots, narrow slits, and sharp corners

Limitations:

·Slow speed, not suitable for large-area material removal

·Electrode wear affects precision

·Can only machine conductive materials

·High cost

Application in the Mold Industry

EDM and CNC are complementary:

CNC milling: Handles most material removal

Sinker EDM: Handles deep slots, narrow slits, and sharp corners that CNC cannot reach

Wire EDM: Handles precision holes, punches, and dies

A mold is typically roughed and mostly finished by CNC first, with the remaining "dead corners" and precision areas left to EDM.

Haina's EDM

Summary

EDM is a machining method that uses the high temperature of electrical discharge to erode metal. It is divided into two types: Sinker EDM and Wire EDM. Its core value is the ability to machine ultra-hard materials, complex shapes, and precision areas that traditional cutting tools cannot handle.

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