Sinker EDM — for deep cavities and corners wire can't reach.
Sinker (ram) EDM uses a custom electrode shape to erode 3D pocket geometry into hardened material. Where wire EDM cuts through, sinker cuts into. Deep blind cavities, broken-tap extraction, sharp internal corners with floor. Routed through K+G Ai ERP with full DFM and electrode-program archive.
Three-dimensional geometry into hard material.
Sinker EDM is the right tool when geometry is blind, deep, sharp-cornered, or impossible to reach with a rotating cutter. Electrode (often graphite or copper) is machined first, then sunk into the workpiece.
Deep pocket cavities
Aspect ratios that exceed end-mill reach. Pocketed inserts for plastic-injection tooling, die-cast inserts, forging dies.
Sharp internal corners with floor
Wire EDM gives sharp corners on a through-cut. Sinker gives sharp corners on a blind floor. Stamping inserts, forming punches.
Broken-tap and broken-tool extraction
Tap snapped in a hole? Sinker burns it out with no collateral damage to the parent material. Common rescue job for high-value parts.
What gets sunk.
Sinker work concentrates in tooling, aerospace, and rescue jobs.
Wire EDM
For through-cuts, square internal corners, intricate flat profiles.
/ CapabilityCNC milling
Rough out the cavity, finish with sinker EDM. Combined op.
/ MaterialTool steel & carbide
Sinker EDM's native material — cut after heat treat without distortion.
/ IndustryAerospace
Turbine cooling channels, mil-spec inserts, structural cavities.
Sinker EDM questions, answered.
What's the difference between wire EDM and sinker EDM?
Wire EDM cuts through-features with a thin electrode wire. Sinker EDM erodes blind 3D pocket geometry with a custom-shaped electrode. Wire cuts through; sinker cuts into. Different work.
What kind of cavities does sinker EDM handle?
Deep blind cavities, sharp internal corners with a defined floor, complex 3D pocket geometry. Mold cavities, forging dies, and aerospace blade root forms.
Can sinker EDM remove broken taps or hardware?
Yes — broken-tap extraction is one of the cleanest uses for sinker EDM. No collateral damage to surrounding threads or features.
What electrode materials do you use?
Graphite for high-speed bulk roughing, copper for fine finishing and complex geometry. Electrode selection drives surface finish and accuracy.
Tolerances on sinker EDM work?
±0.0002″ standard. Surface finish to 16 µin Ra with fine-finish settings. Tighter quoted to print.
Send the print. Quote in 24 hours.
Sinker quotes need cavity geometry + material hardness + electrode access strategy.