Wire EDM is often the answer when a part requires features that seem almost impossible to produce. For example, internal corners with microscopic radii, slots narrower than a human hair or thin walls that would buckle under cutting pressure.
Twin City EDM & Mfg. has used this process for decades to produce parts that push the boundaries of what conventional machining can achieve. The underlying principle is straightforward. Instead of using mechanical force to remove material, wire EDM uses controlled electrical sparks to erode the workpiece along a programmed path. Because the wire never makes physical contact with the material, there is no cutting pressure, no tool deflection and no mechanical stress transferred to the part.
For engineers and product developers working on next-generation devices, this means they can design features that would otherwise be off-limits. A narrow internal slot, a sharp interior corner or an intricate profile in a hardened material doesn’t require rethinking the design to accommodate tooling limitations. The geometry drives the process, not the other way around.
How the Process Works in Practice
Wire EDM operates by passing a thin, electrically charged wire through a workpiece while submerging both in deionized water. The wire generates a series of rapid electrical discharges that melt and vaporize tiny amounts of material from the workpiece and then the deionized water flushes away the eroded particles and it cools the part to prevent thermal distortion. The part experiences no mechanical forces that might cause warping, burrs or stress fractures because the wire itself doesn’t come into contact with the material.
This is valuable when working with heat-treated steels, titanium or other materials that have already been hardened for their final application. Traditional cutting methods would struggle with these materials because they usually require annealing and rehardening cycles that add time and risk to a project. Wire EDM cuts them directly, in their final metallurgical state, preserving the properties that made them the right choice in the first place.
The Scale of Possibilities
One of the most compelling aspects of wire EDM is the level of detail it can produce. The wire itself can be as thin as 0.004 inches and the process can cut internal radii as small as 0.0015 inches.
For context, that is roughly one-fiftieth the thickness of a standard business card. Contour tolerances hold at ±0.0002 inches, with hole tolerances reaching ±0.0001 inches. Those numbers translate into real-world performance gains in products ranging from surgical navigation tools to aerospace components.
For instance, take a medical marker radial. These components require fine slits and radiused ends in stainless steel and any burr or residual stress could affect imaging accuracy or surgical outcomes. Wire EDM produces these features cleanly with uniform geometry from part to part because the process doesn’t depend on tool wear or cutting pressure.
Similarly, aircraft sleeves with internal slots and contours need exact repeatability to meet aviation standards and wire EDM holds those tolerances without deforming thin walls or introducing stresses that could compromise structural integrity.
Materials That Work With Wire EDM
Because the process uses electrical discharge rather than cutting tools, it only works on conductive materials. That includes a broad range of metals and alloys, from common grades to specialty materials engineered for demanding environments. At Twin City, we cut stainless steel, aluminum, titanium, tool steel, carbide, copper, brass, bronze, nickel and a variety of alloys including Inconel, Kovar and Nitinol. We also work with graphite, conductive ceramics and powdered metals.
The breadth of materials is important because many next-generation products rely on exotic alloys that offer specific thermal, electrical or mechanical properties but are notoriously difficult to machine using traditional methods. Nitinol, with its shape-memory behavior and Kovar, with its controlled thermal expansion, are examples where wire EDM often becomes the preferred (or only) feasible approach.
Capabilities That Cover the Whole Project
Wire EDM isn’t a one-size-fits-all process and the equipment supporting it varies in capability. Twin City operates machines with up to five-axis cutting, allowing for complex tapered shapes and angled features that would be impossible with simpler systems. Part sizes can reach 53 inches in length, 30 inches in width and 20 inches in height, with part weights up to 600 pounds. Wire diameters range from 0.004 to 0.012 inches, giving flexibility to match the wire size to the required feature detail.
Supporting that equipment is a range of inspection tools, including Hexagon CMMs with scanning heads and QPM vision systems, to verify every dimension. Testing methods such as pull testing, magnetic particle testing and pressure testing provide additional layers of quality verification. The facility holds ISO 9001:2015 and ISO 13485:2016 certifications, which means the systems used for medical device components meet the same requirements that regulatory bodies expect.
Turnaround times typically run one to two weeks and the shop supports everything from prototype quantities to full production volumes. This matters for companies that need to move through multiple design iterations quickly or scale up after successful testing.
When to Consider Wire EDM
The decision to use wire EDM generally comes down to geometry, material and tolerance. If a part has sharp internal corners, narrow slots, thin walls or any feature that would require a very small tool to reach, wire EDM warrants serious consideration. If the material is hardened, brittle or otherwise challenging to machine, wire EDM sidesteps the usual difficulties. And if the tolerance band is measured in ten-thousandths of an inch, wire EDM delivers that level of consistency without the tool wear that would compromise a conventional machining process.
It also works well for parts that will go through secondary operations, because the wire EDM process leaves a clean surface without burrs. In many cases, parts come off the machine ready for assembly or the next step in production, reducing the need for additional finishing processes.
Twin City has been working with wire EDM for over six decades and that experience shows up in how the team approaches each project. The process is straightforward in concept but demands careful attention to parameters, wire choice, flushing and setup to get the desired result. That knowledge makes the difference between a part that meets the drawing and one that performs as intended in the final application.
