When the parts are challenging or impossible to produce with conventional machining methods, the manufacturers often turn to electrical discharge machining.
The EDM does not rely on physical contact between the tool and workpiece to remove the material. Therefore, no mechanical cutting force is involved, resulting in lower tool wear and deformation.
The EDM process is commonly used in a wide range of industries, such as Aerospace, Medical, Automotive, Electronics, and Mold making. Do you want to know how it works, the types available, and its advantages?
Let us dive in.
What is Electrical Discharge Machining(EDM).
You might heard that some engineers and manufacturers use the term
EDM, but what does that mean?
EDM refers to electrical discharge machining, which is also known as
spark machining. It is a non-traditional manufacturing process that
utilizes periodical electrical discharges to remove excess material from
a workpiece.
The EDM is a precise process that is an ideal choice for forming complex shapes and is capable of machining hard materials like titanium. The materials must be electrically conductive to ensure a successful EDM
process.
In EDM process, a controlled spark is created between the tool electrode
and the workpiece electrode, which erodes the material and forms the desired shape. This erosion occurs in a dielectric fluid, which acts as a
coolant and prevents the electrode and workpiece from coming into
contact.
Working Principle of Electrical Discharge Machining.
The basic working principle behind the EDM process is the thermal energy transfer.
In the EDM process, the tool-electrode(also called a cathode) connects to the negative terminal of a DC power supply, while the positive terminal of the power supply connects to the workpiece electrode (also known as anode). The cathode is typically made of copper or graphite.
The two electrodes are not contact, there is a small spark gap (typically 0.01-0.05mm) between them. Both electrodes immerse in the dielectric fluid like kerosene or deionized water.
When the electrical discharge cycle starts, the power supply generates a high voltage pulse between the two electrodes, it breaks down the dielectric fluid and forms a tiny discharge channel.
Due to the energy being highly concentrated ( 10-107W/mm), it causes a high temperature of the material, the heating results in melting away microscopic particles from the workpiece surface.
By then the discharge terminates, after a very short time interval, the second high voltage pulse will be created. This cycle is repeated thousands of times per second to form the desired shape on the workpiece.
Types of Electrical Discharge Machining.
The EDM process is conventional, however, it does not mean that there is only one type of this process. The electrical discharge machining can be divided into three different types, these include:
1). Wire EDM
It is also known as wire erosion or wire-cut EDM. In this wire EDM process, a thin wire is continuously fed from a spool which acts as the electrode, The controller of the EDM machine guides the wire movement to cut the desired shape on the workpiece.
Be aware that the wire must pass through the workpiece in this process.
The wire EDM can be used for producing parts with high precision, such as gears, dies, and molds.
2). Sinker Electrical Discharge Machining
This is the conventional EDM, also known as Ram EDM. This process uses a pre-machined electrode to form the required shape in the workpiece.
In the sinker EDM process, a high voltage pulse between the two electrodes generates electrical discharge to erode the material in the workpiece, in this process, both electrodes are submerged in the dielectric fluid which cools the materials and washes away the removed material with clean dielectric liquid.
Normally, Sinker EDM is used for producing parts with deep cavities and intricate details, such as complex molds or toolings.
3). Hole-drilling EDM
This EDM process is used to machine holes, especially very tiny and deep holes. The hole-drilling EDM uses the same principle as sinker EDM.
However, the electrodes are tubular, enabling the dielectric fluid to feed
into the cutting area easily.
Unlike the traditional drilling process, the holes made by hole drilling EDM don’t require any deburring. As long as the material is electrically conductive, this process can drill the holes effectively regardless of the hardness or type of the material.
One of the applications of hole drilling EDM is in turbine blade manufacturing.
Advantages of Electrical Discharge Machining over Traditional Machining Methods?
Electrical discharge machining has several advantages over the traditional manufacturing methods. Some of them include:
1). No Contact Occurs Between the Tool Electrode and the Workpiece
EDM is a non-contact machining process that the tool doesn’t need to touch with the workpiece. Therefore, no mechanical cutting force is involved, this is of benefit to eliminate the tool wear and deformation, resulting in a longer tool life and surface finish improvement.
2). Fit for Machining Any Electrically Conductive Material
EDM process can work on a wide range of materials. It is always the right machining choice for electrically conductive Materials. Some materials are difficult to machine for traditional machining methods like titanium and tungsten carbide. However, EDM is no issue to machine those materials.
3). Suit for Machining Harden Material
Unlike the conventional machining methods that need to be done before hardening the workpiece, the EDM works well on hardened steels and heat-treated alloys. The process does not generate significant heat, therefore, it is easy to avoid material deformation or heat-affected zones.
4). Enables complex shapes and deep cavities
EDM process can machine the complex shapes and deep cavities that are challenging to produce with conventional machining methods. You can easily cut sharp corners, deep holes, and narrow slots with the electrical discharge machining process.
5). Electrical Discharge Machining is Cost-Effective in Some Applications
Compared to traditional machining equipment, the initial investment of an EDM machine may be higher. However, the EDM is capable of machining hard materials, reducing tool wear, and eliminating some of the secondary operations, resulting in long-term cost savings in the manufacturing process.
Conclusion:
The EDM process helps to produce the materials where the conventional methods are difficult or impossible to do. It has been a great machining option for the parts with complex shapes and deep cavities.
If you have any complex parts to produce, consider to our high-precision EDM service. Upload your design files today, and you will receive a quick quote. All our services come at competitive prices.
Reference:
EDM.