11
Apr
2012

Engineering and EDM

If it is difficult ot define engineering. Before there were civil engineers, chemical engineers and mechanical engineers. Now we have engineers to do with genetics, the environment, IT and software, to name but a few. Engineering in its broadest sense is taking theory and putting it into practice; to take information from the theoretical realm and put it into the practical one to make machines and processes.

The German inventor, Albert Hanson, described flat foil conductors laminated to an insulating board, in multiple layers. From this description engineers over the years have managed to make printed cicuit boards. As theory has advanced so designers and engineers have continued to refine printed cicuit boards that have become the basis of the computer industry and thus the information age.

In 1770 the English physicist Joseph Priestley discovered the erosive effects of electrical discharges. It took scientists and engineers until the 1940s to develop EDM or electrical discharge machining that uses the discovery made by Priestley. It is a process using two electrodes. One EDM electrode is usually made of graphite, the other is the piece that is to be cut (this must be conductive). A high voltage is run from one electrode to the other through the medium of a dielectric liquid that is either water or oil. When the two electrodes come close enough together hundreds of thousands of small sparks are given off. These sparks erode the two EDM electrodes. The result is that the graphite electrode can be moved to precisely cut the workpiece electrode. In this way very hard metals and alloys can be cut to a high precision. This process is also called spark erosion, sink erosion and wire erosion.

There are several key companies around the world supplying the graphite for this process. These include Pocographite and Toyo Tanso. Companies such as Erodex, based in the UK, are manufacturing graphite electrodes as well as tooling parts. Applications are varied but include products for the aerospace industry and automobile industry.

As with printed circuit board engineering and design, the graphite industry is one of the unsung heroes in modern technology.