Wednesday, February 22, 2017

The Electrical Discharge Machining Process

The electrical discharge machining process is something like a cross between black magic and a highly technical discipline. In spite of the fact that every aspect of EDM is defined in technical terms, to succeed you need instincts and intuition. This makes it rather unique in the injection mold making process.

Most intuition is a result of anticipating outcomes based on previous experience, and the working in the EDM department is no exception. A sort of 6th sense is developed by operators, probably due to the fact that it is so incredibly easy to make a mistake. It seems that no amount of mold making training can take the place of direct, hands-on experience.

 Electrical Discharge Machining Process
Hansterfer’s EDM Dielectric Oil

Electrical discharge machining is fascinating, but frustrating. Rewarding, but it can reduce the best of toolmakers to near tears.

The EDM Process for your mother

There are several excellent descriptions available that describe the electrical discharge machining process in great detail. These are scientific, technical papers that reveal just how this mysterious machining process occurs.

The the layman, however, these are too technical. Just imagine trying to explain to your mother what EDM is. She is mostly interested because she is your mother, so the explanation has to be rather quick, but still make sense.

I tell people that it is like welding in reverse; instead of adding metal, it removes metal. Ask them to visualize pressing your fist into a ball of bread dough. It leaves the impression of your fist in 3 dimensions.

EDM is like that, except that the work is done by all those zillions of sparks that slowly erode the steel to reproduce the shape of the electrode. This seems to make sense to most people and they nod, as if they understand.

What kind of person does well in WEDM and Sinker EDM?

I can certainly tell you what type of person does not do well, which should give an idea of who does well. You cannot be a space cadet, flaky, disorganized, distractible, sensitive to criticism, indifferent, or easily confused. Neither can you be one who has little endurance, patience, fortitude and tenacity.

You do have to have a certain amount of bravado and a willingness to take chances; that is, once you have determined that the odds are in your favor.
You must be highly focused, able to solve problems, willing to try new things, open to ideas from others, and willing to work long hours.

These qualifications probably eliminate most people, hence the shortage of skilled EDM operators. It is one thing to push buttons and change workpieces and electrodes, quite another to produce high quality injection mold components that fit together with mating parts to produce accurate plastic products.

 Electrical Discharge Machining Process
EMD Inc. Copper Electrode

Becoming a successful EDM operator or machinist takes a unique combination of caution and daring; you proceed with great caution and confidently obtain the results you need.

How can you learn the EDM process and succeed?
Basically there are two paths to becoming a successful electrical discharge machinist or operator: learn on the job or at a technical college. Because there are not that many schools offering courses in EDM, most people learn on the job.

Even those who attend a technical college and earn an Associates degree soon discover that they too are going to learn on the job. The degree certainly helps to land the job and gives an technical edge, but the reality is that life in a mold making shop can be fast-paced and high pressure.

Either way, you learn on the job. One EDM friend of mine declared that “EDM is where you go to die a slow death”. Sounds worse than it is though. It is just that there are so many pitfalls and “snakes in the grass” that you become extremely diligent about the details.

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