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How EDM Works

EDM operates on the principle of erosion by electrical discharges. Proces zahŕňa nasledujúce kroky:

Nastavenie: The workpiece and the tool (electrode) are submerged in a dielectric fluid (usually oil or deionized water).

Approach: The electrode is brought close to the workpiece, maintaining a small gap known as the spark gap.

Discharge: A voltage is applied between the electrode and the workpiece, causing a spark to jump across the gap. This spark generates intense heat, melting and vaporizing a small amount of material from both the workpiece and the electrode.

Flushing: The dielectric fluid flushes away the eroded particles and cools the area, making it ready for the next discharge.

Repetition: This process is repeated thousands of times per second, gradually removing material and shaping the workpiece.

Types of EDM Machining

Drôtové EDM (WEDM):

• Proces: Use thin, continuously moving wire as the electrode to cut through the workpiece.
• Aplikácia: Ideal for cutting intricate shapes, thin-walled parts, a prísne tolerancie.
• Výhody: Vysoká presnosť, ability to cut hard materials, and no tool wear.

Sink or Ram EDM:

• Proces: Uses a shaped electrode submerged in a dielectric fluid and moves towards the workpiece to erode the material.
• Aplikácia: Suitable for deep cavities, zložité tvary, and mold making.
• Výhody: Can machine hard materials, high accuracy, and no mechanical contact between tool and workpiece.

Small Hole EDM:

• Proces: Specialized for drilling small holes, typically using a small-diameter electrode.
• Aplikácia: Used for cooling channels, nozzles, and other small feature machining.
• Výhody: High precision and capable of drilling very small holes.

Key Features of EDM Machining

Non-Contact Machining: The workpiece is not physically touched by the tool, reducing stress and deformation.

Presnosť: Capable of achieving very fine tolerances, often within ±0.0001" (±0.0025 mm).

Všestrannosť: Can machine a wide range of materials, including hardened steels, carbides, and superalloys.

Komplexné tvary: Ideal for machining intricate and complex shapes that are difficult to achieve with traditional methods.

Advantages of EDM Machining

• ● Material Hardness: Can machine very hard materials, including hardened steel, karbid volfrámu, a titánu, which are challenging for traditional machining.
• ● Complex Geometries: Capable of producing intricate shapes, sharp corners, and delicate features.
• ● No Mechanical Force: Since there is no direct contact between the tool and workpiece, EDM is ideal for machining delicate or thin-walled parts without causing deformation.
• ● High Precision: Offers excellent accuracy and surface finish, making it suitable for precision components.
• ● Minimal Tool Wear: Electrode wear is generally less of a concern compared to traditional cutting tools.

Applications of EDM Machining

Mold Making: Used extensively in the production of molds for injection molding, tlakové liatie, and other forming processes.

Letectvo a kozmonautika: For machining complex parts with tight tolerances, such as turbine blades, komponenty motora, and fuel system parts.

Lekárske pomôcky: Use in the manufacturing of precise components like surgical instruments, implantáty, a zdravotníckych pomôcok.

Semiconductor Industry: Used to create microstructures and precise features in semiconductor wafers and other components.

Tool and Die Making: Used to make precise dies, formy, and other tooling components.

Key Considerations for EDM Machining

Electrode Material: The choice of electrode material (grafit, meď, or brass) affects the machining efficiency, wear rate, and surface finish.

Dielektrická kvapalina: The type and quality of the dielectric fluid influence the machining stability, povrchová úprava, and material removal rate.

Spark Gap Control: Maintaining a consistent spark gap is crucial for achieving precision and preventing short circuits.

Heat Affected Zone (HAZ): EDM generates heat, which can affect the material properties near the machined surface. Proper flushing and cooling are essential to minimize the HAZ.

Cost and Efficiency: While EDM can achieve high precision and complex geometries, it is generally slower and more expensive than traditional machining methods, making it suitable for specific applications where these capabilities are essential.