Sinker EDM: Burning Where No EDM Has Burned Before

Sinker EDM is a seemingly magical process. For example, what other machining technology can cut square internal corners, deep ribs and pockets, and paper-thin slots, all using a simple chunk of graphite or copper? Granted, broaching can do some of this, but it needs a special cutter and can only cut certain part geometries. And machining these shapes in hardened tool steel or carbide? Forget it. Only sinker EDMs can cut these shapes.

What’s more, it’s highly accurate. Sinkers can hold tolerances in the “tenths” and generate mirror finishes, whatever the material (provided it’s electrically-conductive, that is). And while hard milling on CNC machining centers has given sinker EDM a run for its money lately, sinker remains irreplaceable in many applications.

Sinker EDM History

Ironically, the invention of sinker EDM was an accident. Twice. In 1943, a husband and wife team of Russian scientists were searching for ways to minimize wear on electrical power contacts. They found that the cause of such wear—electrical discharge—can be used to remove metal. At around this same time, an American engineering team was looking for a way to remove broken taps from workpieces. They succeeded, using a series of sparks from an electrode submerged in water to slowly erode the tools. Sinker EDM was born.

Sinker Basics

Thanks for the history lesson, but how does sinker EDM work now? First off, it uses advanced electronics and high-speed power supplies to precisely control spark generation. Those early machines produced sixty or so sparks per second. By comparison, modern equipment like Kent USA’s KEB-series sinker EDM generates hundreds of thousands sparks per second. The result is far greater machining efficiency. Add in precise motion control and easy programmability, and these machines fill a gap that other technologies can’t.

Other Considerations

In all fairness, there’s far more to sinker EDM than described here. Shops new to sinkers or those shopping for an upgrade will be pleasantly surprised at the range of available features. Artificial intelligence that automatically adjusts machining parameters. A menu-driven LCD display. Simultaneous three-axis control. A 45-degree tilt head equipped with a C-axis rotary spindle. These are just a few of the functions that make these machines more capable and easier to operate than ever before. If you need to sink some complex shapes in a mold base or burn some ribs in a heatsink, give us a call about our newest KEB-series machine, the KEB-600L CNC. It’s the best thing since graphite.