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EDM (Electrical Discharge Machining) is a non-conventional machining process that uses thermal energy to remove material from an object.
Just like laser cutting, electric discharge machining doesn’t require mechanical force to remove excess material from a workpiece in order to create a required shape. This is what makes the EDM process different from traditional cutting tools.
In this article, we’ll discuss the working mechanism of EDM machines and the different types of EDM machining processes, their applications, and their advantages and disadvantages.
It’ll help you understand how our electric discharge machining services can help you improve your manufacturing process.
What is EDM?
EDM (Electrical Discharge Machining) is a non-conventional precision machining process that removes material from a workpiece using thermal energy instead of mechanical force. Also known as spark machining, EDM uses electrical sparks, reaching 14432 to 21632 Fahrenheit (8000 to 12000 Celsius), to cut and shape objects.
How Does the EDM Machine Work?
EDM machining comes in handy when other machining processes, such as CNC machining, can’t generate the desired cut, like a deep cavity or sharp internal corners.
This process can be used to machine conductive materials and create complex shapes with high accuracy. The process is relatively slow and is typically used for small batch sizes.
The EDM machine consists of a tool electrode, non-conductive dielectric fluid, a DC power supply, servo control, and a workpiece. The EDM working process is carried out through a series of current discharges between the workpiece and the tool electrode.
The tool electrode is connected to the negative terminal, and the workpiece is connected to the positive terminal of the power supply.
It’s important to note that an air gap, also known as a spark gap, of 0.005 to 0.5 mm is maintained between the workpiece and tool throughout the process using dielectric fluid, which is forced through the gap under pressure.
When the power is turned on, the dielectric fluid gets ionized, creates a spark, and increases the temperature, which melts and removes the material of the workpiece in a small area.
It also means that the EDM uses electricity, instead of a cutting tool, to remove material from a workpiece.
The servo control feeds the tool continuously to maintain the spark gap and carry out the electrical discharge machining process. It allows EDM to achieve an accuracy of as low as 0.001 mm.
Electrical Discharge Machining Types
The three different types of EDM machining help you choose the alternative method(s) if one doesn’t suit your needs.
Sinker EDM
The sinker EDM, also known as Ram EDM, conventional EDM, volume EDM, cavity type EDM, or die sinking, is a machining process that can create complex shapes for different applications like plastic injection molding.
The die sinks EDM machine has pre-machined copper or graphite electrodes to have the required shape. The shaped electrode sinks into the workpiece and generates the mirrored version of the original shape.
Wire EDM
Also known as spark EDM or wire erosion, wire EDM involves the use of thin copper or brass wire that acts as the tool electrode to cut the workpiece.
Flickr Image by Argonne National Laboratory
A wire-cut EDM machine typically has deionized water as the dielectric fluid. There is a continuous wire unfurling from an automated feed through a spool.
That’s because the wire or workpiece may compromise the electrical discharges in this process. For that reason, wire-cut EDM machines continuously need a new discharge path in the cut.
Hole EDM
Hole EDM or hole drilling EDM is used specifically for fast hole drilling. These EDM machines have tubular electrodes that help the dielectric medium flow through them easily.
Unlike traditional drilling methods, the benefit of using hole EDM machining is that it allows you to machine extremely small and deep holes. Plus, the holes created through this process also don’t need any deburring.
Applications of EDM
EDM machining is commonly used in small-volume production for different processes such as small-hole drilling, turning, and milking. It’s also used in a range of different industries, ranging from aerospace to the automotive industry.
Here’s a list of the most common applications where you can utilize our EDM services.
- Injection molding is one of the most common uses of wire EDM. Even with complex workpieces, it can help you achieve a mold’s accurate shape, depth, and dimension.
- EDM is a quick way to produce precise deep small/micro holes drilling in different material types, regardless of their hardness level.
- Traditional machining methods don’t work effectively for this purpose because of the hard steel alloys that are commonly used in die casting. Electrical discharge machining allows manufacturers to create accurate dies with deep ribs and sharp internal corners.
- EDM can also be used to disintegrate different parts, such as taps, drill bits, and studs, of a workpiece that you can’t remove easily.
Advantages and Disadvantages of EDM
Just like any other machining process, EDM has its own set of advantages and disadvantages that you should know.
Advantages
- Can machine any electrically conductive workpiece
- Works effectively in head-treated conditions to machine hard materials
- Can reproduce even the most complicated shapes and depths made on the tool
- Allows you to achieve an accuracy of as low as 0.001 mm
- Can create desired results economically
- No mechanical force is required, unlike laser cutting
- Long lifespan because of proper cooling and lubrication
- It can create an erosion-resistant and hard surface on dies easily
- Can produce tapered holes
- End-result doesn’t require burring
- Can machine fragile and thin workpieces without deforming them
Disadvantages
- It can only be used for conductive materials
- High power consumption
- Excessive tool wear
- Low rate of material removal
- It can cost extra time and money to prepare electrodes (for sinker EDM)
Final Words
Electrical discharge machining is an innovative method that can machine different conductive materials and create complex shapes with impeccable accuracy.
You can utilize our EDM services in conjunction with traditional machining processes like CNC machining to take your manufacturing process to the next level.
If you need such services, you can contact us today to get a quote to transform your manufacturing process and stand out from the crowd.
