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Die-sinking EDM
László Bándoli
Operating Principle
The core principle of the technology is to introduce a high amount of electrical current in pulses between a workpiece and an electrode (tool), while a dielectric fluid (hydrogenated hydrocarbon-based insulating oil) separates the two. The pulses generate micro-discharges on the surfaces, causing local melting of the material, followed by its removal.
Key elements of the process:
- The shape of the electrode corresponds to the negative form to be created.
- The workpiece is always grounded.
- The arc discharge repeatedly occurs, and the electrode also wears down (electrode wear).
- Precise electronic control is required to regulate the process steps.
- Continuous circulation of the dielectric fluid is essential to carry away the removed material particles.
Its Role in Toolmaking
Die-sinking EDM allows the creation of geometries that would be impossible or extremely difficult to produce using other technologies.
- Injection mold inserts – machining complex shapes (e.g., pins, ribs, vents, logos) in hardened steel.
- Die-casting tools – machining deep pockets in high heat-resistant inserts for aluminum and zinc die-cast components.
- Cold and hot forming tools – precise fabrication of punches and dies.
- Manufacturing custom and trial inserts – rapid prototyping for small series production.
Key Advantages in Toolmaking
- Outstanding shape accuracy and surface finish.
- Capability to produce interlocking and complex contours.
- Hardened materials can be machined without requiring pre-heat-treatment processing.
- Material removal without mechanical stress—no internal tensions induced.
Disadvantages
- Slow machining, especially for deep cavities.
- Electrode manufacturing can be time-consuming and costly.
- Due to electrode wear, multiple re-adjustments may be required.
The Role of Die-Sinking EDM in Toolmaking
Die-sinking EDM is a key technology in the field of tool manufacturing. It is a machining process that enables the creation of highly complex, precision shapes from extremely hard and difficult-to-machine materials. It is primarily used in the production of components and inserts for injection molds, die-casting, and forming tools.
