Things You’ve Always Wanted To Know About Sinker EDM

Jul 19, 2021
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A Few Of The Things You Always Wanted To Know About Sinker EDM But Were Afraid To Ask…

Kent-USA-Sinker-EDM-606N-60ASinker EDM is an improbable machining process. It relies on high-voltage electrical current to remove material, so there’s no direct contact between the workpiece and tool. For that matter, there’s no actual cutting tool in the traditional sense of the word. Instead, a chunk of graphite, copper, or tungsten “erodes” the metal. For finishing applications, this “electrode” is usually shaped like a mirror image of the workpiece. EDM machinists also use rounds and rectangles for roughing. Whatever its shape, the electrode is gradually consumed during the process.

Some people refer to Sinker EDM as Ram or conventional EDM. The wise-guys in the group call them “stinkers.” That’s thanks to the smell of the burning metal. Whatever. Sinker EDM is an ideal process for a wide variety of machining work. This includes forming dies and mold cavities, internal splines, blind keyways, and complex features in any electrically-conductive material.

Back to the USSR

Sinker EDM has been around a long time. The English scientist Joseph Priestly first observed the erosive effects of electrical current way back in 1770. If you’ve ever shorted out an electrical socket with a screwdriver, you might have seen the same thing. Regardless, it was a pair of Russian physicists (a husband and wife team, no less) who invented electrical discharge machining. It wasn’t long before manufacturers began using it to remove broken taps and make tools. A few decades later, others went on to develop wire EDM, something we’ll discuss in a future blog post. Today, it is an important technology for machining the hardened steels common in the tool and die world.

Sinking Deep

Experts will tell you there are three things to know about these capable machine tools: flushing, flushing, and flushing. Then they laugh like it’s the funniest joke they’ve ever heard. It’s true, though. Proper flushing is crucial to efficient EDM operation. It removes the bits of burnt metal and electrode from the work zone. These are then carried away by the “dielectric” (a type of non-conductive fluid) and into the machine’s filtration system. A high-performance power supply is also crucial. For example, Kent Industrial USA’s largest sinker, the EDM KEB-808B, boasts 90-amps. That’s plenty of power for removing lots of metal quickly.

Shopping for Sinker EDM

There’s more to EDM success than power, however. Kent USA uses a MOSFET electric discharge circuit design on all its sinker EDM machines. This promotes fast burning. It also reduces electrode wear, and generates a high-quality, uniform surface finish. Kent also uses precision linear guideways and lubricated ballscrews for maximum accuracy. A 3-axis digital readout with auto Z-depth settings makes operation easy. So does the ability to program up to 500 steps (depending on the model), with cycles for unattended machining. The CNC version even has an optional C-axis and ATC (automatic tool changer) and advanced programming functions. If you’re in the market for a robust sinker EDM at a very fair price, there’s a lot here to like. Give us a call if you’d like to chat about it.

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