Electrical discharge machining is a type of metalworking that uses electrical discharge, leading to erosion of the material. This method is mainly used in the manufacture of punches, dies and other parts for punches and stamping dies. From the article, you will learn the advantages of EDM machining and exactly what the process looks like!
What is EDM cutting?
EDM cutting is a machining process that is based on the contact of an electrode with the surface of a material, such as metal. However, the working tool of the machine tool has no physical contact with it, there is only a flow of dialectic fluid, in which an electric voltage is generated. The gap between the material and the electrode can be up to 0.8 mm. A high temperature is generated at the point of voltage discharge, which causes the material to melt and evaporate, resulting in the desired shape.
EDM is used wherever conventional metalworking methods are not applicable. The great advantage of this method is the possibility of making extremely precise and even complex shapes, despite the hardness of the material. This machining works well in high-volume and mass production, as it enables high process repeatability.
Interestingly, the origins of EDM date back to 1770. At that time, scientist Joseph Priestley discovered the erosive effect of an electric charge on metal. So the method has been in use for many years now, and its popularity continues to grow.
WEDM or EDM machining?
WEDM machining is very often compared to EDM machining. There is nothing surprising about this – WEDM is a variation of EDM machining, or electrical discharge machining. The main difference between the two methods is in the type of working electrode used. In the WEDM technique, it is a wire that rewinds and shapes the workpiece, while the interelectrode gap is flushed with dielectric under sufficiently high pressure. This allows the removal of material formed during melting, or evaporation of the cavity.
WEDM machining-as well as EDM-makes it possible to cut difficult-to-cut materials with extreme precision. Even materials such as titanium, tool steel, polycrystalline diamond or sintered carbides can be processed. Thus, the WEDM method is characterized by a wide range of applications and is slightly different from conventional EDM.
The two machining methods also have a common feature. Both methods work well for machining very small and detailed designs. WEDM, however, pays off for a small number of parts, while EDM is a better solution for mass production and high volume production.
The biggest advantages of WEDM machining are high tolerance, no impact cutting, and easy creation of complex shapes. For EDM cutting to be possible, you need a device, namely an EDM machine tool. There are two types of it:
- eD die-sinking machine,
- wire cutting machine.
The difference between the two devices concerns the shape of the electrode. In the former, it has the shape of the hollow workpiece.
Electrical discharge machining – application
EDM is used primarily for machining hard materials that cannot be machined using milling or turning. This method is used for, among other things:
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- production of stamping dies,
- production of forging tools,
- production of surgical instruments,
- production of miniature gears for watches,
- production of highly miniaturized components,
- production of punches for stamping and bending of sheet metal parts,
- production of punches,
- production of casting and injection molds,
- production of punches,
- production of cutting tools,
- for machining fuel rods,
- for machining turbine and compressor blades in aviation,
- precision metal cutting.
EDM cutting – advantages and disadvantages
EDM cutting has many advantages as well as disadvantages. Positive aspects of it are:
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- the possibility of machining small, hard and demanding parts,
- the lack of direct contact between the tool and the workpiece, making it possible to machine delicate and weak materials without damage,
- the possibility of obtaining a well-finished surface,
- the possibility of obtaining small holes,
- the possibility of obtaining complex and non-trivial shapes,
- the possibility of machining materials that cannot be machined by traditional methods.
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In turn, the disadvantages of this solution are:
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- slow rate of material removal,
- creation of electrodes, which requires additional time and cost,
- high energy consumption,
- high power consumption,
- regular wear and tear of electrodes that require repair after time,
- difficulty in reproducing sharp corners,
- the possibility of machining non-electrically conductive materials only with a specific process setting.
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Thus, EDM is a complex, but extremely necessary process that makes it possible to obtain a variety of shapes even for demanding materials.