EDM at Viteris

Viteris designs and builds small form factor micro-EDM machines for wire-EDM, sinker-EDM and milling-EDM. We can deliver these as both standard general-purpose machines or highly specialized for a particular application. In addition, we are currently pursuing research in the area of highly parallelized EDM where several electrodes are simultaneously controlled to machine multiple features in a way that makes EDM competitive with other micromachining techniques in volume production runs.

Electrical Discharge Machining

Electrical discharge machining (EDM) is non-contact process capable of removing material at very small lengthscales without creating mechanical stresses. The material is removed through highly localized melting and evaporation as a result of electrical discharges from an electrode to the material. The discharges, which form tiny plasma channels with temperatures up to 10,000 °C, locally melt very small amounts of material. As the plasma collapses when the current flow is shut off, the resulting vacuum pulls out the molten material into the surrounding dielectric medium.

Micro-EDM

Micro-EDM is a specialized form of EDM whereby the workpieces have features as little as 10 microns (0.0004 inches). These small features are achieved with electrodes that are also very small in size. For EDM sinker and EDM milling, the typical features are internal geometries such as holes, slots, etc. Therefore, the electrodes are typically a tiny bit smaller than the features to be machined. For wire-EDM (micro-WEDM), where most featured are external features, this restriction is not necessarily the case.

High-aspect ratio features

Unlike popular micromachining techniques such as laser or lithography-based techniques, micro-WEDM generates part geometries that are closely tied to the geometry of the electrode. As a result, very high-aspect ratio features such as microelectrode arrays can be machined (Fig 1). Another advantage of micro-WEDM is the fact that the electrode can be actuated on toolpaths that allow complex geometries to be machined (Fig 2+3).


Fig 1 Microelectrode arrray (silicon) machined with micro-WEDM with aspect ratios up to 40:1 (Source: Precision Design Lab, University of Utah)


Fig 2 Microelectrode array (after etching) with complex electrode geometries machined with micro-WEDM 1. (Source: Precision Design Lab, University of Utah)


Fig 3 Microelectrode array (after etching) with complex electrode geometries machined with micro-WEDM 1. (Source: Precision Design Lab, University of Utah)

Rotational features

By adding a rotational axis to a micro-WEDM, complex workpieces such as helical swimmers can be machined (Fig 4+5)


Fig 4 A helical swimmer machined from 1 mm diameter Nitinol tubing with a magnet attached to the tip. (Source: Telerobotics Laboratory, University of Utah)


Fig 5 SEM image of helical swimmer (without tip magnet). (Source: Precision Design Lab, University of Utah)

Machinable materials

As an electro-driven process, the workpiece material must be sufficiently electrically conductive. All metals, regardless of their hardness, can be machined by EDM. In addition, it is possible to machine semiconducting materials as well if their level of doping is sufficient to conduct the discharge current. In general, the material resistivity should be 10 Ohm-cm or less. Under very specific circumstances, it is possible to machine non-conductive materials by coating the workpiece with a thin layer of conductive material. In these special cases, the workpiece must be relatively thin.

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