Have you ever heard of EDM before? In this case, we aren’t talking about electronic dance music, but instead a revolutionary piece of technology known as an Electrical Discharge Machine. This nifty technological process uses electricity to shape materials with precision, and today, we’re going to be taking a closer look at what it’s all about.
First, Some Background
Broadly speaking, EDM is a “subtractive electro-thermal manufacturing method,” which just means that it uses electricity to take away from a material and shape it into the desired form. It’s quite impressive when you see it in action, and its great advantage is that it’s highly accurate and capable of working on very hard materials—like tungsten and titanium. That doesn’t mean it’s a perfect process, however, as Brian Pfluger—an EDM product line manager—points out while providing comment for a report on WIRED:
“A shortcoming of EDM, though, is that it’s a slower method than mechanically machining parts. With typical methods, you’re going to set the cruise control at 60 miles an hour to just cruise on down the highway. With EDM, you’re going to hit a little bit more traffic.”
This is due to constant adjustments that need to be made to the EDM machine’s alignment during the shaping process, and that’s necessary to prevent the machine’s wire from coming into contact with the workpiece (which could cause it to snap and lead to a whole slew of issues). So, with EDM it’s got to be slow and steady, but the results are top-notch.
Types Of EDM
Up to this point, we’ve been speaking in generalities about EDM and its most common subtype: wire EDM. That’s not the only variety there is, however, and it’s worth explaining the differences between three of the most popular forms of EDM:
- Wire EDM: You might also hear this referred to as wire erosion or wire spark EDM. It makes use of (you guessed it) a thin piece of wire as an electrode. The electrical discharge is then used to make precise cuts on the work material.
- Sinker EDM: Sinker EDM goes by several alternate names—RAM EDM, die sinker EDM, cavity type EDM, and volume EDM, to name a few. The method makes use of graphite (or copper) electrodes, and “sinks” those electrodes into the work material to get the desired dimensions. It’s often used in making plastic injection molds and metal stamping dies, and is ideal because of the complex shapes it can create.
- Hole-Drilling EDM: As the name suggests, hole-drilling EDM is all about creating those tight, precise holes that you can’t get by any other means. It utilizes a rotating conductive tube, which serves as an electrode, to make its accurate cuts. Then, the process employs a dielectric fluid to flush the cut and get the finished product. You’ll find this process used for any sort of job that requires pinpoint holes within very hard materials—one that’s incredibly smooth and also doesn’t require deburring.
Though slow when compared to other manufacturing techniques, EDM is capable of amazing precision on tough work materials—an ability that moves this to the top of the pack when it comes to cutting-edge processes that are moving the industry ahead.