Electrical discharge machining (EDM) has long been a favorite of tool and die makers. Why? Because it has the ability to cut through any conductive metal, regardless of its hardness. It can also generate shapes otherwise impossible to produce, and hold tolerances once reserved for jig grinding.

Still, these qualities are just as important to medical, aerospace, and many other industries. As a result, what some have long considered a niche process has become mainstream. Job shops in particular are finding that EDM increases profits and sales opportunities alike.

Down to the Wire

Two types of electrical discharge machining exist; sinker and wire. However, the more common, at least among the industries listed just now, is wire EDM (WEDM). This WEDM machine from Kent USA is one well-known example. It boasts a submerged tank, auto threader, linear guideways, and other features critical to precision machining.

WEDM uses a spool of “traveling wire” to carry high voltage electric current. To prevent a short circuit, deionized water or oil surrounds and insulates the wire. Made of brass or copper alloy, this “electrode” follows a path determined by the CNC control. Think of it as you would a cutting tool, precisely eroding metal as it passes.

Sinking Deep

Secondly, there’s sinker EDM. These machines are a common sight in any mold shop. Some refer to it as conventional EDM, like this CNC sinker from Kent USA. With a 60-amp power supply, MOSFET circuitry, a Side Loran function and other advanced features, it promises years of dependable productivity.

Sinkers use an electrode made of graphite (most common) or copper. This electrode typically contains a mirror shape of the desired workpiece geometry, similar to a form tool on a CNC machining center. And as with WEDM, an oil dielectric insulates the charged electrode.

But where WEDM employs X and Y axis motion to cut parts, sinker EDM plunges vertically, in the Z-axis. Sometimes, however, the operator will also program an orbiting motion to rough out the feature before finishing, or to create other shapes. In addition, a C-axis option (as with Kent’s KEB-600L CNC sinker) increases flexibility, since it allows positioning of the electrode at precise angles.

Electrical Discharge Machining Considerations

Can’t decide? Both styles are solid choices, but it really comes down to the workpiece geometry. If you need to cut a blind pocket in a piece of hardened tool steel, sinker EDM is a great option. But if you need to machine precision through-holes or slots, WEDM could be the way to go. As such, the first step is to speak with an expert on these and other applications.

That expert is Kent USA. The company has decades of experience with electrical discharge machining. And if that’s not the right approach, Kent’s sales and service engineers can steer you toward the most effective solution. Give us a call.