Electrospark machining (EDM) is a precision machining technology that uses the discharge phenomenon of electric sparks to remove metal materials. This technology is widely used in the manufacture of high-hardness, difficult-to-cut metal materials and workpieces with complex shapes, especially in mold manufacturing, aerospace, electronics and automotive industries.
The basic principle of EDM
The basic principle of EDM is to form a short-term high-frequency pulse electric spark between the electrode (tool electrode) and the workpiece. The high temperature generated during the discharge process will cause the metal material to partially melt or even vaporize, thereby removing the material layer by layer to achieve precision machining. During the machining process, a certain gap is always maintained between the workpiece and the electrode, called the "discharge gap", and the entire machining process needs to be carried out in a working fluid with certain insulating properties (such as spark oil or deionized water) to facilitate cooling, remove machining chips and control the electric field strength.
Main types of EDM
EDM can be divided into the following main types:
Die Sinking EDM: uses a die electrode with a shape opposite to the workpiece for processing, and is used to manufacture molds and parts with complex shapes.
Wire EDM: uses a continuously moving thin metal wire as an electrode to cut the material, and is suitable for cutting complex contour shapes.
Small Hole EDM: uses a slender tubular electrode to process small holes, which is suitable for processing deep small holes, exhaust holes, etc.
Characteristics of EDM
Advantages
It can process materials with extremely high hardness, such as cemented carbide, hardened steel, etc.
It can process complex shapes, tiny structures, deep holes and other precision parts that are difficult to achieve with traditional methods.
There is no mechanical cutting force during processing, and no tool wear and thermal stress deformation will occur.
Disadvantages
The processing speed is slow, especially for thick parts and large areas.
A heat-affected zone will be generated during processing, which may cause the surface of the workpiece to harden.
The tool electrode will be worn, especially when processing precision shapes, which requires high requirements for electrode materials and design.
Common Materials for EDM
Brass: Brass is an alloy of copper and zinc and is widely used in EDM due to its good electrical conductivity. Brass is also a preferred metal for EDM due to its wear resistance and ease of machining.
Aluminum: Aluminum can be used in wire-cut EDM to machine fine details and complex geometries. Aluminum's high thermal conductivity helps to dissipate heat efficiently, ensuring minimal thermal damage during EDM. Aluminum also corrodes very easily, which allows for efficient material removal and the manufacture of parts with complex geometries.
Steel: The hardness and strength of steel make it ideal for EDM as it helps to create durable molds. It can also be used as an electrode during the process, but only when specific thermal properties are required.
Copper: In wire-cut EDM, copper ensures efficient spark generation, resulting in precise cuts. Their wear resistance makes them ideal for EDM in mold production. Copper electrodes dissipate heat well, making them ideal for drilling EDM where clean, precise holes are important.
Applications of EDM
Aerospace: This technology can produce various aerospace parts, including stator blades, turbine disks, and compressor disks. In addition, it helps to manufacture landing gear components, fuel system components, molds, aviation blades, and metal molds, all of which are necessary for the safe and efficient operation of aerospace vehicles.
Mold manufacturing: Processing complex mold cavities, such as injection molds and stamping molds.
Precision parts: Manufacturing high-precision parts in aviation, aerospace and other fields.
Medical equipment: Making parts with micropores and complex shapes, such as implants, micro-mechanical parts, etc.
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