What are the working principles, types, and applications of Electrical Discharge Machining (EDM) ?

• What are the working principles, types, and applications of Electrical Discharge Machining (EDM) ?
  • What is electrical discharge machining (EDM)?
  • Working principle of electrical discharge machining
  • Electrical Discharge Machining Types
    • Electrical Discharge Machining
    • Wire EDM
    • Small hole electrical discharge machining
  • EDM manufacturing processes are suitable for parts with complex designs .
  • When should you choose electrical discharge machining (EDM)?
  • Materials suitable for EDM
  • What are the advantages and limitations of EDM technology?
  • Application areas of electrical discharge machining
  • Choosing the right EDM service provider – Elimold
  • in conclusion
  • FAQ

Machining processes are becoming increasingly popular due to their ability to produce parts with desired features. Machining processes are primarily used to remove material from workpieces. Sometimes, these processes cannot produce the desired features, which can be achieved through another machining process: Electrical Discharge Machining (EDM). EDM is a new technology that utilizes electrical and thermal energy for machining. The difference between EDM and conventional machining is that the tool does not contact the workpiece during EDM. This article will explain the working principle of EDM, the materials it can machine, its applications, and its specific advantages.

What is electrical discharge machining (EDM)?

Electrical discharge machining (EDM) is a process that uses electrical energy, rather than traditional mechanical force, to refine materials or metal parts. It is often used when machining methods are ineffective or pose potential risks. For example, if conventional machining cannot produce sharp grooves or edges like CNC milling, engineers use EDM to obtain the desired shape.

Generally speaking, electrical discharge machining (EDM) is efficient and fast regardless of the metal’s hardness. There are many types of EDM equipment, and they can usually produce the desired shapes with greater precision. For example, engineers can use EDM to create extremely small holes in hard metals. However, a common drawback of EDM is that excessive material can be removed if operated improperly or the system is poorly designed. This phenomenon is called material “wear,” and therefore, measures must be taken to prevent its effects.

Electrical discharge machining (EDM) uses electrical energy to remove material layer by layer from an object, typically metal. In this process, engineers can use the primary material to create the desired shape. Engineers can also use this process to create and apply a wide range of details and complex structures in their designs. Traditionally, engineers need to heat the metal to soften it and then reshape the softened metal into the desired shape. Typically, the metal needs to cool to room temperature and harden again before it can be used. This is very time-consuming and labor-intensive, and often makes it difficult to machine small, complex, or precise shapes. EDM provides a solution because it uses electrical energy and typically eliminates the need to melt the metal to soften it.

Working principle of electrical discharge machining

Electrical discharge machining (EDM) works by using “sparks” to remove or corrode metal materials. First, the metal to be processed using EDM must be conductive. At the start of the process, a spark is generated in the system. When this spark strikes the metal, it creates a hole. The hole forms because a portion of the metal is burned away. Therefore, engineers sometimes refer to the principle they use as “electrical discharge machining.”

In the entire electrical discharge machining (EDM ) process , the tool electrode and workpiece are connected to the two poles of a pulse power supply, respectively, and immersed in the working fluid or filled into the discharge gap. An automatic gap control system controls the tool electrode’s feed to the workpiece. When the gap between the two electrodes reaches a certain distance, the pulse voltage applied to the electrodes breaks down the working fluid, generating a spark discharge. A large amount of heat energy is concentrated in the microchannel during the instantaneous discharge, with temperatures reaching 10,000℃ or higher, and the pressure also changes drastically. Therefore, a small amount of metal material immediately melts on the work surface, and the flammable mixture splashes onto the working fluid, condensing rapidly in an explosive manner to form solid metal particles, which are then carried away by the working fluid.

At this point, tiny pits are left on the workpiece surface, the discharge briefly stops, and the working fluid between the two electrodes returns to an insulating state. Then, the next pulse voltage breaks down at the other point where the two electrodes are relatively close, causing a spark discharge, and the above process is repeated. In this way, although the amount of metal removed by each pulse discharge is very small, a large amount of metal can be removed due to thousands of pulse discharges per second, resulting in a certain productivity. By maintaining a constant discharge gap between the tool electrode and the workpiece, the tool electrode is continuously fed into the workpiece while the workpiece metal is being eroded, ultimately machining a shape corresponding to the shape of the tool electrode. Therefore, by changing the shape of the tool electrode and the relative movement between the tool electrode and the workpiece, various complex curved surfaces can be machined.

This process is superior to traditional cutting methods. However, for many, traditional cutting techniques remain more popular because training is generally easier. Electrical discharge machining (EDM) requires a pre-designed workpiece and skilled technicians to perform the machining.

Electrical Discharge Machining Types

There are several types of electrical discharge machining (EDM), but they all share the common feature of using electrodes to generate sparks during the machining process. Experienced engineers can choose the appropriate type based on their needs. If you are a beginner, you can read the introduction to each process to understand how to achieve the desired results.

Electrical Discharge Machining

Engineers often choose electrical discharge machining (EDM) to design or finish complex cavities. This process also utilizes sparks to generate electrical discharges. By removing some metal through electrical discharge, a finely shaped metal part is formed. EDM is performed on a conductive workpiece. First, the engineer creates a graphite electrode, the shape of which must be the opposite of the desired final metal shape. While the electrode is being made, the required mold is completely immersed in a container filled with a dielectric fluid. Now you understand why it’s called “electrical discharge machining.” Next, the mold moves towards the workpiece, and as it approaches the area called “electrical breakdown,” sparks are generated in a channel within the workpiece called the “spark gap.” Sparking and combustion then occur. Some of the metal melts, and the dielectric fluid carries away some of the molten metal particles. This process continues until the metal gradually takes on the shape the engineer desires.

Wire EDM

As the name suggests, wire electrical discharge machining (EDM) uses electrical wires to perform electrical discharge machining. The wires are used to cut metal until the correct shape or form is achieved. These are special wires that act as electrodes and are continuously fed into the workpiece. As the machining process proceeds, the metal is machined into the desired shape. This method requires a liquid, typically deionized water. Due to its tensile strength, the wires are usually made of brass.

Let’s say you want to cut a hole in the middle of metal. First, you need to drill a small hole in the middle of the metal or any object. Then, using a diamond guide and electrical discharge machining (EDM), the metal is secured to the workpiece. Generally speaking, wire EDM is usually more precise, more economical, and more versatile.

Small hole electrical discharge machining

If engineers need to drill holes quickly, they might use small-hole electrical discharge machining (EDM). As the name suggests, it involves applying electrodes to a tubular hole to allow the dielectric fluid to flow freely. This method is very effective for creating small, deep holes. In small-hole EDM, the hardness of the metal is not a limiting factor.

EDM manufacturing processes are suitable for parts with complex designs .

Electrical discharge machining (EDM) is the most efficient EDM method for producing parts with complex or precision cavities. This is because it is better suited for drilling, deburring, finishing, 3D contouring, and other machining processes. Furthermore, EDM is particularly suitable for manufacturing parts that cannot be produced using conventional machining techniques because its ability to cut materials is unaffected by material hardness. Its cutting capabilities make EDM the preferred method for machining parts with complex internal features such as cavities and pockets.

When should you choose electrical discharge machining (EDM)?

EDM can perform a variety of tasks, such as drilling long or narrow holes in any metal, extracting precise 2D shapes from difficult-to-machine materials, and creating complex cavity shapes that are essentially 2D relief shapes cut into the bottom of 3D blind cavities. You can also use EDM to cut extrusions, rotating parts, and sharp internal corners. Notably, EDM applies almost no tension to the workpiece, allowing for perfect drilling in a single pass across any cross-section.

Materials suitable for EDM

EDM manufacturing technology can create complex shapes and patterns on workpieces, and it can also process most conductive materials. Cuttable materials include:

aluminum	Aluminum has excellent thermal and electrical conductivity. However, aluminum is inherently soft and may develop a sticky residue after processing. If handled improperly, it can be difficult to cut during machining.
titanium	Wire electrical discharge machining is well-suited for titanium because the process can handle the alloy’s stickiness and break down long, thin chips. However, deionized water is required as a medium to help control the heat generated during the machining process.
steel	Steel is a very strong metal, and many manufacturers prefer to use wire EDM machines rather than CNC machine tools to machine complex steel features. However, this material generates a lot of heat, so necessary precautions must be taken.
brass	Brass has high tensile strength and is easy to cut by machine. However, the cutting speed is slow because it is a soft metal.
graphite	Graphite is difficult to cut using traditional cutting tools, but wire electrical discharge machining is suitable because the sharp wire prevents particles from precipitating out.

What are the advantages and limitations of EDM technology?

Here are some advantages and disadvantages of using EDM technology:

advantage		shortcoming
accurate	EDM can achieve tight tolerances as low as ±0.005 mm.	High production costs	Several factors, including high energy consumption, excessive tool wear, and excessively long processing time, can affect the cost of producing parts using EDM.
Complex shapes	Electrical discharge machining (EDM) can produce complex shapes and features that are difficult to process using traditional methods.	Low material removal rate	As discussed, electrical discharge machining (EDM) gradually erodes the material. This makes its material removal rate much slower than that of traditional machining processes such as milling and turning.
Design flexibility	Easily machine complex shapes and hard materials such as tungsten and nickel.	Only applicable to conductive materials	Because the introduction of electrical discharge generates heat, which corrodes the material on the workpiece, EDM processing is incompatible with non-conductive materials such as composite materials, plastics, and other dielectric materials.
No mechanical deformation	Non-contact processes can prevent warping and damage to precision components.	High electrode cost	Custom electrodes used for mold forming increase costs, especially in small-batch production.
Excellent surface finish	A smooth surface can be left with minimal post-processing.

Application areas of electrical discharge machining

Electrical discharge machining (EDM), with its high precision and versatility, is suitable for various industrial processes, especially in areas where traditional machining methods are inadequate. The most common application industries for this type of machining include:

medical equipment	Manufacturers use EDM to produce surgical instruments and complex implants.
aerospace	Used to manufacture critical components such as engine parts and turbines.
defense	Develop essential components for military equipment and vehicles.
Tool and mold manufacturing	EDM can generate molds, castings, and stamps.
Research and Development	Used to create experimental parts and prototypes.
car	Molds required for the production of automotive parts.
Manufacturing machinery	Used to generate complex mechanical parts, including gears and threads.
Electronic products	Used for the mass production of semiconductor components and other connectors.

Choosing the right EDM service provider – Elimold

When choosing a suitable EDM service provider, it’s best to look for providers with industry experience. Select a service that offers different EDM technologies, such as settling tanks, wire mesh, and drilling. It’s also advisable to verify their processing capabilities and compare their EDM equipment with the size and complexity of your project.

Looking to manufacture parts using EDM? Then Elimold is the perfect choice. We are a multi-functional manufacturing company offering a full range of services including EDM, CNC machining, sheet metal fabrication, 3D printing, and more. No matter your production scale—whether you’re prototyping, small-scale, or large-scale manufacturing—we guarantee high-quality parts and one of the fastest lead times in the industry. Contact us today for a free quote.

in conclusion

Electrical discharge machining (EDM) is an effective metal forming method that can be used to manufacture parts of various shapes to meet diverse applications. There are several types of EDM, each with its unique advantages. Small-hole EDM is best suited for machining small holes in metals, even those with high hardness. This article also explores different types of EDM techniques, including drilling, sinker EDM, and wire EDM, and delves into the advantages, disadvantages, and applications of these processes to ensure you make an informed decision when choosing the EDM technique that best suits your needs.

FAQ