Build An EDM PDF - Overview
Build An EDM – Electrical discharge machining (EDM), also known as spark machining, spark eroding, die sinking, wire burning or wire erosion, is a metal fabrication process whereby a desired shape is obtained by using electrical discharges (sparks). Material is removed from the work piece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage.
One of the electrodes is called the tool-electrode, or simply the tool or electrode, while the other is called the work piece – electrode, or work piece. The process depends upon the tool and work piece not making physical contact. When the voltage between the two electrodes is increased, the intensity of the electric field in the volume between the electrodes becomes greater, causing dielectric break down of the liquid, and produces an electric arc.
As a result, material is removed from the electrodes. Once the current stops (or is stopped, depending on the type of generator), new liquid dielectric is conveyed into the inter-electrode volume, enabling the solid particles (debris) to be carried away and the insulating properties of the dielectric to be restored.
Build An EDM
Build An EDM – Types
- Sinker EDM
- Wire EDM
- Fast hole drilling EDM
Build An EDM – Applications
- Prototype production
- Coinage die making
- Small hole drilling
- Metal disintegration machining
- Closed loop manufacturing
Build An EDM – Advantages and disadvantages
Advantages of EDM include:
- Ability to machine complex shapes that would otherwise be difficult to produce with conventional cutting tools.
- Machining of extremely hard material to very close tolerances.
- Very small work pieces can be machined where conventional cutting tools may damage the part from excess cutting tool pressure.
- There is no direct contact between tool and work piece. Therefore, delicate sections and weak materials can be machined without perceivable distortion.
- A good surface finish can be obtained; a very good surface may be obtained by redundant finishing paths.
- Very fine holes can be attained.
- Tapered holes may be produced.
- Pipe or container internal contours and internal corners down to R .001″.
Disadvantages of EDM include:
- Difficulty finding expert machinists.
- The slow rate of material removal.
- Potential fire hazard associated with use of combustible oil based dielectrics.
- The additional time and cost used for creating electrodes for ram/sinker EDM.
- Reproducing sharp corners on the workpiece is difficult due to electrode wear.
- Specific power consumption is very high.
- Power consumption is high.
- “Overcut” is formed.
- Excessive tool wear occurs during machining.
- Electrically non-conductive materials can be machined only with specific set-up of the process