The search continues: graphite or copper – which to choose?

Related Vendors

HASCO Hasenclever GmbH + Co KG

BORIDE Engineered Abrasives

Meusburger Georg GmbH & Co. KG

Poco Graphite, Inc. an Entegris Company

The phenomenon of releasing electrons

The thermophysical properties of the electrode material determine the ability to process the energy of the EDM cut and remove metal. In generating a spark, peak current is discharged only after the gap between the electrode and workpiece is broken down.

At this point, the electrode emits electrons that collide with the molecules of the dielectric fluid. With copper electrodes, the phenomenon of releasing electrons takes place only after its own material has melted.

This is why on-times for copper electrodes are generally much higher than a graphite electrode. On the other hand, a graphite electrode is able to emit these electrons at much lower temperatures and the time required to form the energy channel is considerably less.

Aluminium tooling: Applying the right alloy

With the sophistication of today’s EDM sinker technology, the surface finish gap between graphite and copper has narrowed significantly. Fine grain graphite electrodes are now able to deliver similar surface finishes much faster than copper with comparable wear on the electrode.

Test burns completed and performance tracked

In order to identify the monetary impact of both graphite and copper electrodes, test burns were completed and performance tracked. With the results of this testing, the true cost was identified.

The parameters of these tests were set to test EDM identical electrode details to a depth of 1” using two electrodes (1 rough and 1 finished) and then determine if additional electrodes were required to complete the job. For these tests, the electrode detail was not critical and a standard rib was chosen for simplicity. The electrode materials chosen were a Poco EDM-3 graphite electrode in the “Ultrafine” classification and an “oxygen-free” C110 copper electrode.

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