Firstar Adds Sinker EDM Machine to Shop Lineup
Firstar is expanding its Electrical Discharge Machining (EDM) capabilities with the addition of a new sinker EDM machine, operational as of July 2026. This investment was driven by a multi-part project from a local client that was experiencing less-than-ideal lead times and pricing on sinker EDM work. Bringing this capability in-house allows Firstar to improve turnaround, cost, and control for customers with complex EDM requirements.
What Is Sinker EDM?
Sinker Electrical Discharge Machining is a non-contact machining process that uses electrical discharges to remove material and form precise, complex features in conductive metals. Unlike mechanical cutting, sinker EDM uses a shaped electrode and a dielectric fluid to gradually erode the metal surface, creating an “impression” of the electrode in the workpiece.
This process is especially valuable for:
- Internal features that are difficult or impossible to reach with traditional cutting tools
- Intricate geometries in hardened or exotic materials
- Tight-tolerance features that must be consistent from part to part
Because the material is removed via electrical discharge rather than cutting forces, sinker EDM can achieve highly accurate, repeatable features on delicate, high-precision components.
Sinker EDM vs. Wire EDM
Both sinker and wire EDM rely on the same core technology — controlled electrical discharge — to remove metal with excellent accuracy and surface finish. The main difference lies in how that energy is applied and what kinds of features each process can produce.
Wire EDM
- Uses a continuously fed, electrically charged wire that must pass completely through the part
- Ideal for through-features, profiles, and cutouts where there is an entry and exit path for the wire
- Common for complex geometries, precision blanks, and tight-tolerance contours
Sinker EDM
- Uses a shaped electrode that is plunged into the workpiece
- Does not require a pass-through, making it ideal for blind cavities and internal features
- Well-suited for internal gear features and other shapes that can’t be wire cut or easily shaped by conventional tooling
With the new sinker EDM machine, Firstar can now apply EDM technology to a broader range of part geometries while maintaining the same tight tolerances and precision customers already expect from its wire EDM work.
Firstar is also able to produce the shaped electrodes needed for sinker EMD work on our wire EDM machines. The full process can be started an completed in our Brunswick, OH facility – giving our customers speed and efficiency needed for their programs.
How Customers Can Use Firstar’s Sinker EDM Capability
Firstar’s new sinker EDM machine opens up several options for customers:
- Full-part manufacture with EDM features – Firstar can manage machining the part and performing the sinker EDM operation in-house.
- EDM-only work – Similar to existing wire EDM projects, customers can send in parts and have Firstar perform sinker EDM on specific features only.
- Complex internal features – Internal gear forms and other blind or hard-to-reach features that can’t be created using wire EDM or conventional machining.
As with our wire EDM services, Firstar’s goal is to provide reliable lead times, consistent quality, and responsive communication throughout the quoting and production process.
Requesting a Quote for Sinker EDM Work
If you have an upcoming project that may be a fit for sinker EDM, our team can review your requirements and provide a quote, whether you need full-part production or EDM-only work.
To start a quote, email sales@firstarcnc.com and include (where available):
- Part drawings and models
- Material specifications
- Required tolerances and critical features
- Target quantities and desired lead times
Firstar’s team will confirm whether sinker EDM is the right approach for your geometry and requirements and outline next steps for moving your project forward.
