Introduction
Choosing between Wire Cut EDM and Sinker EDM is one of the most important decisions a tool room manager makes. Both use electrical discharge to remove material, but they work in fundamentally different ways and serve different purposes.
This guide breaks down everything you need to know to make the right choice.
How Wire Cut EDM Works
Wire Cut EDM uses a thin brass or coated wire (typically 0.1–0.3mm diameter) as the electrode. The wire moves continuously through the workpiece, cutting a narrow kerf like a bandsaw — but with electrical sparks instead of teeth.
Best for:
- Through-cutting profiles and contours
- Punch and die manufacturing
- Complex 2D shapes with tight tolerances
- Thin slots and narrow features
- Parts requiring excellent surface finish (Ra 0.15 µm achievable)
Limitations:
- Can only cut through the workpiece (no blind cavities)
- Requires a start hole for internal features
- Slower than milling for simple shapes
How Sinker EDM Works
Sinker EDM (also called Die Sinking EDM or Spark EDM) uses a shaped electrode — usually copper or graphite — that "sinks" into the workpiece. The electrode shape is the negative of the cavity being created.
Best for:
- Complex 3D cavities and pockets
- Injection mould cavities
- Blind holes and internal features
- Textured surfaces
- Hard materials that are difficult to mill
Limitations:
- Requires custom electrodes (adds time and cost)
- Electrode wear must be managed
- Slower material removal than wire EDM for through-cuts
When to Choose Wire EDM
Choose Wire Cut EDM when you need:
- Through-cutting with tight tolerances (± 0.005 mm)
- Complex profiles in hardened steel
- Excellent surface finish without secondary operations
- Unmanned 24/7 production capability
- Punch and die manufacturing
When to Choose Sinker EDM
Choose Sinker EDM when you need:
- 3D cavities that can't be through-cut
- Injection mould tooling
- Textured or contoured surfaces
- Ribs, slots and deep features
- Mirror finish (Ra ≤ 0.1 µm with PIKA circuit)
The Berlin Recommendation
Most serious tool rooms need both technologies. Wire EDM handles profile work and punches, while Sinker EDM handles cavities and complex 3D work. If you can only invest in one machine first, choose based on your primary work:
- 80% profile work? → Start with Wire EDM
- 80% cavity work? → Start with Sinker EDM
- Mixed work? → Wire EDM offers more versatility for general use
Contact Berlin's application engineers for a personalised recommendation based on your specific parts and volumes.