Is EDM Right For Your Manufactured Parts?
When English scientist Joseph Priestly first noticed how electrical sparks could cut through metal in 1770, he likely never imagined that Electrical Discharge Machining, or EDM, would become a mainstay in the manufacturing world.
EDM is a non-contact machining method that creates an electrical current between a conductive workpiece and an electrically charged shape or wire composed of a brass, copper, graphite, or tungsten alloy. The spark generated by the electrical current erodes the material, and a non-conductive fluid, such as deionized water or oil, washes away any waste.
EDM first took off in the 1940s and gained popularity in the 1960s as capabilities increased. Still, most engineers are more familiar with CNC machining and consider EDM a non-conventional manufacturing process. EDM has a reputation for being slower and more expensive than CNC machining.
However, EDM manufacturing has advanced significantly in recent years, improving cost and efficiency and minimizing recast issues that were previously a concern.
What makes a project a good candidate for EDM services? Here’s everything you need to know.
Top 4 Factors for Choosing EDM
1. Geometric requirements
With EDM, it’s possible to cut precision keyways, hexes, internal splines, shaft pockets and slots, and other unique features without making custom (i.e., expensive and time-consuming) broaches. There are times when only EDM can produce the specific, complex geometric shapes that a part requires.
Need to cut through curved or angled surfaces? No problem—EDM can navigate virtually any contour, and Micro-Tronics’ talented team members manage varying tapers with exceptional precision. EDM can also handle fragile and thin sections because the wire electrodes never actually contact the workpiece.
2. Hardened materials
EDM is an excellent choice when making parts from very hard materials such as tool steel.
These materials are difficult to cut using traditional machining methods. They cause significant tooling wear, yielding low-accuracy results and rough finishes.
Since EDM uses electrical current, the risks of tooling wear is eliminated entirely. It’s possible to cut through many hard, conductive materials with precision, ease, and speed.
3. Delicate features and fine finishes
Intricate designs are easier to render with EDM manufacturing than CNC machining. If your project has delicate features, EDM’s non-contact process eliminates cutting stress and mechanical distortion, resulting in a superior quality part.
EDM also produces exceptional finish quality. Mirror-like finishes are possible with this process, and with no secondary polishing operations required, customers can save time and money.
4. Quick turnaround
EDM is a great choice if time is of the essence. Since it’s usually a toolless solution requiring minimal setup and programming, we can get your project up and running quickly.
At Micro-Tronics, we’ll also help you optimize lead times with quick quoting and leverage our in-house tool room for rapid specialty fixturing and electrodes.
Now that you know the benefits and capabilities of EDM manufacturing, it’s essential to understand the types of EDM services available.
The 3 Types of EDM Services
1. Wire EDM
In wire EDM, the electrode is brass wire. Think of it as a “super-precision band saw” that can make through-hole parts. Wire EDM is consistently reliable and can produce burr-free, perfectly straight parts. While a traditional drill can drift, wire EDM doesn’t waver. It’s a great alternative to broaching for short timelines or small-to-medium volume runs.
At Micro-Tronics, we pride ourselves on our rotary wire EDM services. We can make a wide variety of precise, complex shapes—economically and efficiently—through the “turn and burn” technique. We use the same machine to burn one side of the workpiece, then turn it and burn the next side without changing out the workpiece. This streamlined process saves our customers time and money.
2. Sinker EDM
Sinker EDM traditionally uses a graphite or copper electrode. The electrode itself is made into a specific shape which is then burned into the workpiece to create the part.
Primarily used to produce blind cavities, Sinker EDM can create internal splines and keyways with no through-holes.
Sinker EDM is the solution when the job requires sharp corners, intricate details, fine finishes, and the machining of undercut surfaces. It’s also ideal for hardened materials, and its non-contact method combined with low-pressure flushing makes it perfect for thin and delicate parts.
3. Small hole EDM
If your part requires a deep, tiny hole, you’ll need small hole EDM services. Small hole EDM can manage minuscule diameters (.007” – .25”) and achieve high aspect ratios while cutting perfectly straight into the workpiece. Meeting these dimensional requirements would likely cause CNC machining tools to break or shatter.
Small hole EDM is fast, accurate, and can handle curves and angles. Small hole EDM also eliminates the need to deburr drilled holes post-machining.
What About Recast?
One last EDM consideration is the issue of recast. If you’ve used EDM services in the past, you may have run into this problem.
Recast is a thin layer of molten material that can land on top of the workpiece when sparks create a heat-affected zone. It’s undesirable and can make the surface brittle.
Working with an expert EDM manufacturer will mitigate this issue. At Micro-Tronics, our state-of-the-art anti-electrolysis power supplies and manufacturing techniques can reduce the recast layer to as little as 2.5μm (0.000098”): essentially zero. We remove the recast layer with processes like extrude honing, lapping, and electropolishing—leaving no cracks.
EDM is a great option when projects require delicate details, complex geometric shapes, and tiny, deep holes. If you’re curious about using EDM for your part, we’re happy to help you identify the process that’s best for your project.
We have 50+ years of experience delivering large quantities of EDM manufactured products—we’d be thrilled to partner with you on yours. To get started, request a quote today.