Electrical Discharge Machining

wedm_sparkingEver heard of Electrical Discharge Machining? Want to understand how it works and even build your own system?

Presented here are two of my old DIY manuals available to the public for download; “CNC Sink-EDM” and “CNC Wire -EDM” for the home shop. These manuals were first released in the late 90s early 2000 through Dan Mauch at Camtronics.

The incentive of these manuals, then and now, is that they may be informative and useful. That they may form the basis or platform to build and develop your own EDM system.

WEDMFP


Download Wire EDM for the Home Shop File Size: 6.3 MB Downloads:2,613

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Download Sink EDM for the Home Shop File Size: 12.9 MB Downloads:2,695

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Update: There is some issue with the download of the Sink EDM manual. It appears to be resolved now. But if it still does not work, please try using another web-browser or contact me.

EDM Process

Electro Discharge Machining, or EDM for short, is a special type of manufacturing technique. It involves bombarding a work-piece surface with highly localized electrical sparks. These sparks slowly erode the surface and thereby cut it. The technique is typically used to cut metal, even the hardest of metals and in particular the hardest of metals. It has wide-spread use in modern machine shops and is responsible for cutting some of the most intricate shapes with extreme accuracy.

edm_process

Basic EDM Process

Like most cutting processes it relies on a tool to cut and shape its way through a work piece. Yet, while it cuts through even the hardest of metals there is almost no cutting force involved in the process. In fact, the tool is typically made of a relatively soft, electrically conductive material. It does none of the cutting. Instead it delivers intense sparks to the work-piece and erodes its way through. Electrical sparks bombard the work piece surface, etching it piece by piece and bit by bit.

Ultrasonic EDM Project

A Pen, paint brush, chisel, lathe or IDE. Whatever your art is there is usually a certain tool involved to express it

Converting your ideas into tangible form requires understanding the properties of materials. It also requires understanding manufacturing techniques and the tools involved. Mastering these will allow you master the process of creating that what you want and in the way that you want it.

EDM was gaining a lot of traction and application during the late 80s and early 90s. In part this was due to the ever increasing demand for more intricate and accurate parts in industry. But what was really pushing this manufacturing technique forward was the ever decreasing cost of computational power.

The EDM process requires adjustment and control. Microprocessor controlled systems allowed the EDM process to become almost completely automated. This, in turn, allowed for more consistent and better machining results. It also meant that you could cut shapes in ways that were traditionally considered to be too difficult to produce.

Although seemingly trivial, one of the important elements in the EDM process is flushing. The EDM process is typically performed in a bath of dielectric fluid. This fluid acts as an insulator and coolant between tool and work-piece. It also flushes away material from the strike zone. The fluid properties may degrade during sparking strikes. Hence, flushing makes sure that the strike zone is nourished with fresh fluid and that the area surrounding the strike zone remains electrically consistent and clean of debris.

The importance of flushing became apparent to me early on. Equally apparent was the complexity of the electrical circuit required to ionize the strike path and spark the surface effectively. Was there some way to reduce the complexity of the process and electrical circuit? Was there some way to allow for better surface quality, more effective and faster cutting? Something that would allow for better flushing?

WARNING: EDM fluids are typically flammable substances. Combined with mechanical vibration such as ultrasonics, these fluids can produce highly combustible mixtures. This can be extremely dangerous. You have been warned.

The answer was to have the tool, fluid and/or work-piece mechanically vibrate. Preferably at very high frequency and very low amplitude. It was well known that ultrasonic baths can very effectively clean the surface of materials and even cut through and weld materials through friction. In cleaning, ultrasonics basically create cavitation in the bath fluid. These micro implosions tear at the material surface removing dirt and even oxides.

Could ultrasonics be used to improve flushing and otherwise improve the strike zone conditions? Something that could enhance the process in terms of cutting speed and surface quality and make it easier to control?

To answer this I started to build my own CNC EDM systems towards the late 90s. Around that time sonoluminescence was being investigated and high power ultrasonic components were becoming less difficult to obtain. The systems that I built demonstrated that mechanical vibration and ultrasonics had a beneficial effect on the process. But more investigation was needed to pin down and develop the technology further.

Still in school and with limited income I decided to share some of my work and allow others to build their own EDM systems. Hopefully this would finance my investigations as well as allow me to share more with others.

EDM DIY Manuals

What was the main criteria of the DIY EDM manuals presented here? Simple; To understand the process and provide the means to build your own system. Make EDMing accessible to a larger audience of people interested in this unique machining process. That’s the composition here.

Wire EDM Rig

Wire EDM Rig

That meant providing very practical information. It meant designing a system that was low-cost and relatively easy to construct. Most of us don’t have access to a lathe or a mill. As such, the design does not rely on lathe or mill work. Basic materials and tools will suffice.

The presented design is not the end-product. Instead its the hands-on experience of building and working with a home-built system that is. In other words, the information contained the manuals should serve as a foundation or starting-point to build and experiment with EDM. Ideally, I would hope that others would take it forward and build more advanced home-built systems. Then share that to allow others to do the same. Something similar to Open Source development.

The supplied software stems from another time. A time when DOS ruled. The control software has been supplied only as a template or overview on how the process was controlled. Today there are so many ways to control hardware. In particular I’d be glad to see if boards such as the Raspberry Pi were used to do so.

Completed Sink-EDM System

Completed Sink-EDM System

Spark Your Imagination

One comment on “Electrical Discharge Machining
  1. Perry Engel says:

    Thanks very much!
    I was looking for exactly this sort of information (sink edm).

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