In the factories of automotive component manufacturers, the Electrical Discharge Machining (EDM) process is a method of machining using electrical energy and heat energy. It is mainly used to process conductive materials such as precision machining parts or plastic moulding parts. Its basic principle is to process the workpiece by using the electro-erosion effect generated by pulse discharge between two electrodes in a liquid medium. EDM does not require direct contact between the tool and the workpiece, but instead removes the metal material through the local high temperature generated by the pulse discharge.
Electrical discharge machining (EDM) is a machining process that mainly uses a discharge electrode (EDM electrode) with a specific geometric shape to burn the electrode geometry on a metal (conductive) part. It is almost always used in custom injection molds, die-casting molds, stamping molds, cutting molds, CNC machining parts, etc. It is a process that must be used in injection mold inc and CNC machining parts factory.
Historical background of "EDM"
The principle of "EDM" was discovered as early as the end of the 19th century, but it was not until the 1940s that the Soviet Lazarenko couple discovered that the instantaneous high temperature of EDM would cause local metal to melt, gasify and be eroded when studying the phenomenon of spark discharge corrosion damage to switch contacts, thus creating the EDM machining method. In 1943, they developed the world's first practical "Electrical discharge machining" to truly apply the electrical erosion phenomenon to actual production and processing.
The method of using the corrosion phenomenon produced during EDM to process the size of materials is called "Electrical discharge machining (EDM)". "EDM" is a spark discharge in a liquid medium within a relatively low voltage range. The "EDM" process is mainly completed by injection mold inc. EDM is a self-excited discharge with the following characteristics: There is a high voltage between the two electrodes of the spark discharge before the discharge. When the two electrodes are close, the medium between them is broken down, and then spark discharge occurs. With the breakdown process, the resistance between the two electrodes decreases sharply, and the voltage between the two electrodes also decreases sharply. The spark channel must be extinguished in time after a short period of time (usually 10-7-10-3s) to maintain the "cold pole" characteristics of the spark discharge (that is, the heat energy converted by the channel energy has no time to be transmitted to the depth of the electrode), so that the channel energy acts on a very small range. The effect of the channel energy can cause local corrosion of the electrode.
Application areas of "EDM"
"EDM" is widely used in the processing of various metal parts, and is particularly suitable for processing complex or fine holes and features. Due to its high precision (tolerance range can reach +/- 0.005 mm), it and CNC machining of 5-axis CNC machine are one of the relatively high-precision methods in mechanical processing. EDM processing has significant advantages in the production of complex-shaped workpieces, low-rigidity workpieces and micro-structures. CNC machining car parts, plastic moulding parts, CNC machining for medical devices, plastic mold parts, these products have complex structures or smooth outer surfaces, so "EDM processing" is the most ideal choice at this time. At the same time, it can also ensure that customized metal parts are within a very small tolerance range, which is suitable for high-precision products or parts. Therefore, sometimes some precision machining parts of CNC machining have local complex structures and very small tolerances, and can also be processed by "EDM"
Advantages and disadvantages of EDM processing
Advantages:
Wide application range: Any conductive material can be processed.
No cutting force: Especially suitable for processing complex-shaped workpieces, low-rigidity workpieces and fine structures.
High precision: High-precision processing can be achieved with a small tolerance range.
High flexibility: The pulse parameters can be adjusted as needed, suitable for three-stage processing of coarse, fine and fine.
Disadvantages:
Slow processing speed: Due to the local high-temperature etching of materials, the processing speed is relatively slow (several times slower than direct CNC processing).
Tool electrode loss: The tool electrode will be lost during use, affecting the processing efficiency and forming accuracy (the "tool electrode" is the "copper male" used for discharge made by CNC processing first)
The processing of round parts is not as efficient as "cnc turning", so when we encounter round metal parts, we generally use "cnc turning" for processing.
EDM is a non-contact processing.
The tool electrode and the workpiece are not in direct contact, but there is a spark discharge gap. This gap is generally between 0.05 and 0.3 mm, and sometimes it may reach 0.5 mm or even larger. The gap is filled with working fluid. During processing, high-voltage pulse discharge is used to discharge and corrode the workpiece.
It can "use softness to overcome hardness".
Since EDM processing directly uses electrical energy and thermal energy to remove metal materials, it has little to do with the strength and hardness of the workpiece material. Therefore, soft tool electrodes can be used to process hard workpieces to achieve "use softness to overcome hardness".
It can process any difficult-to-process metal materials and conductive materials.
Since the removal of materials during processing is achieved by the electrical and thermal effects of discharge, the machinability of the material mainly depends on the conductivity and thermal properties of the material, such as melting point, boiling point, specific heat capacity, thermal conductivity, resistivity, etc., and has almost nothing to do with its mechanical properties (hardness, strength, etc.). This can break through the limitations of traditional cutting processing on tools, and can use soft tools to process hard and tough workpieces, and even process superhard materials such as polycrystalline diamond and cubic boron nitride.
Can process surfaces with complex shapes
Since the shape of the tool electrode can be simply copied to the workpiece, it is particularly suitable for processing workpieces with complex surface shapes, such as complex cavity mold processing. In particular, the adoption of CNC technology has made it possible to process complex-shaped parts with simple electrodes.
Can process parts with special requirements
Can process parts with special requirements such as thin walls, elasticity, low rigidity, micro holes, special-shaped holes, deep holes, etc., and can also process small text on the mold. Since the tool electrode and the workpiece are not in direct contact during processing, there is no cutting force of mechanical processing, so it is suitable for processing low-rigidity workpieces and micro-processing.
CNC
CNC EDM is the abbreviation of Computer numerical control Electrical Discharge Machining. CNCEDM is computer numerical control EDM, which realizes multi-axis linkage machining. CNCEDM realizes automatic control through computers to complete complex and precise EDM machining. In the actual machining process, the computer sends instructions to control EDM according to the input program to realize single-axis or multi-axis CNC machining.
In short, "EDM processing" equipment is commonly used for custom metal parts, injection molds, and die-casting molds. We use this process in customized automotive injection molds, medical industry precision molds, die-casting molds for the drone industry, automotive precision metal parts, and other complex and high-precision parts processed by CNC. It is a must-have equipment for automotive component manufacturers.
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