Creating complex cavities with electrical discharge erosion
Sinker EDM, also known as die sinking or ram EDM, uses a shaped electrode that mirrors the desired cavity form. The electrode is slowly lowered into the workpiece while electrical sparks erode the material, creating an exact negative of the electrode shape.
| Material | Wear Rate | Surface Finish | Best For |
|---|---|---|---|
| Graphite | Low-Medium | Good | Large cavities, roughing |
| Copper | Medium | Excellent | Fine details, finishing |
| Copper-Tungsten | Very Low | Excellent | Deep ribs, small details |
| Tellurium Copper | Low | Very Good | General purpose |
Key parameters include: current (1-100A), ON time (50-2000 us), OFF time, voltage gap, and polarity. The right combination determines whether the process favors material removal rate or surface finish quality.