Sinker EDM, also called ram EDM, removes material with controlled electrical discharges rather than cutting force. For copper, this matters because copper’s high conductivity—documented by the Copper Development Association —supports electrodes, terminals, busbars, heat sinks, and RF components. For copper parts with deep recesses, slender walls, or sharp internal edges, sinker EDM generates those details through spark erosion rather than mechanical cutting, which helps limit stress and burr formation.

Why Copper + Sinker EDM?

    ● No mechanical cutting force: ideal for fragile ribs, thin walls, and micro features.

    ● Complex geometry: blind cavities, sharp internal corners, deep slots, and textured surfaces.

    ● Fine finish: lower Ra can be achieved with proper electrode and power settings.

    ● Material integrity: minimal heat-affected zone when parameters are controlled.

    ● Repeatability: electrode wear compensation and orbiting improve batch consistency.

How We Do It

We follow a controlled workflow from DFM to final inspection.

    ● DFM & electrode design: Review 3D/CAD, define split, undersize, orbit, and discharge allowance.

    ● Electrode machining: CNC milling and turning prepare electrodes; our five-axis precision machining supports complex electrode shapes.

    ● Sinker EDM setup: We use Sodick and Makino sinker EDM systems with controlled current, pulse, and flushing.

    ● Finishing & inspection: Deburr, clean, measure critical dimensions, and document results.

Equipment Parameters

These machines support ±0.01 mm machining capability and complex copper parts for aerospace, medical, automotive, electronics, and communication applications. Learn more about our precision equipment list.

Process Notes

    ● Electrode material: copper, copper tungsten, or graphite depending on feature and wear.

    ● Flushing: controlled through-hole, side flushing, or vacuum flushing to remove debris.

    ● Orbit: helps improve sidewall finish and reduce electrode wear marks.

    ● Power settings: roughing removes bulk; finishing lowers Ra and improves edge definition.

    ● Inspection: critical dimensions checked against 3D/CAD requirements.

Example

A medical customer needed a copper micro-cavity insert with 0.15 mm ribs and ±0.01mm tolerance. We machined the copper electrode on a DMG five-axis center, then burned the cavity on a Sodick AD30Ls with multi-step orbit. First-article inspection passed, and the parts shipped in five working days.

Conclusion

Precision copper machining with sinker EDM combines copper’s conductivity with non-contact accuracy. If your project needs complex copper geometry, tight tolerance, or fine surface finish, our team can help. Contact us to discuss your manufacturing needs. Visit Start Precision.

FAQs

Q1: What is sinker EDM used for in copper machining?
A: It creates complex cavities, slots, sharp corners, and fine details in copper without mechanical cutting force.

Q2: Can sinker EDM machine pure copper?
A: Yes. Pure copper and copper alloys can be EDM’d, but parameters must manage conductivity, flushing, and electrode wear.

Q3: What tolerance can you hold?
A: Our general machining capability is within ±0.01 mm, depending on feature, material, and inspection method.

Q4: Do you make electrodes too?
A: Yes. We design and machine copper or graphite electrodes, then use them for sinker EDM.

Q5: How do I request a quote?
A: Send your 3D/CAD files, material, tolerance, and quantity through our contact page.