News & Updates

CONTINUING TO EXPAND OUR EDM DEPARTMENT. We recently purchased a Form20 iRTC Sinker EDM. We now have 9 Ram/Sinker EDMs, 8 hole drilling EDMs and 5 Wire EDMS. Keep us in mind for your EDM work utilizing our NADCAP approved EDM department.

What is an EDM Machine?

The EDM machine was invited in 1943. It is used on hard metals that are electrically conductive. These metals are impossible to machine with traditional methods such as a grinder or end mill, so the EDM Machine is used to cut contours and cavities into the metal.

Typical metals machined on and EDM Machine include hardened tool-steel, titanium, hastalloy and carbide.

An EDM Machine uses an electrode to create electrical discharges to remove metal and make cuts. As the electrical charge passes between the electrode and the metal being machined, cuts are made into the metal. A continuously flowing fluid is used to flush these pieces of material away.

Electrical Discharge Machining Types

There are three types of electrical discharge machining, wire EDM and sinker EDM.

Wire Electrical Discharge Machining

The wire EDM process uses a thin metal wire fed from a spool through the workpiece to cut plates, make punches, tool and dies. In wire electrical discharge machining, the metal and wire cutter are submerged water, which acts as an electrical insulator.

The wire is held between upper and lower diamond guides, which are CNC-controlled and can be programmed to cut very delicate shapes.

A typical use for wire cutting electrical discharge machining is when low residual stresses are desired. This is because the process does not require a high cutting force for removal of materials.

Sinker Electrical Discharge Machining

In the sinker EDM process, an electrode and the metal are submerged in an insulated liquid, in this case it’s usually oil, and a power supply generates an electrical charge between the electrode and the metal. A spark occurs that cuts the metal. In sinker electrical discharge machining, several hundred thousand sparks occur per second.

The spark cycle is controlled by setup parameters known as on time and off time. The on time settings determine the length and duration of the spark.

Small Hole EDM

Small hole EDM is used to drill rows of holes into the leading and trailing edges of turbine blades used in jet engines. Gas flow through these small holes allows the engines to use higher temperatures than otherwise possible. The high-temperature, very hard, single crystal alloys employed in these blades makes conventional machining of these holes with high aspect ratio extremely difficult, if not impossible.

Small hole EDM is also used to create microscopic orifices for fuel system components, spinnerets for synthetic fibers such as rayon, and other applications.

There are also stand-alone small hole drilling EDM machines with an x–y axis also known as a super drill or hole popper that can machine blind or through holes. EDM drills bore holes with a long brass or copper tube electrode that rotates in a chuck with a constant flow of distilled or deionized water flowing through the electrode as a flushing agent and dielectric. The electrode tubes operate like the wire in wire-cut EDM machines, having a spark gap and wear rate. Some small-hole drilling EDMs are able to drill through 100 mm of soft or through hardened steel in less than 10 seconds, averaging 50% to 80% wear rate. Holes of 0.3 mm to 6.1 mm can be achieved in this drilling operation.

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