1. **Advantages** - **High machining accuracy**
- Electrical Discharge Machining (EDM) can achieve very high machining accuracy, usually within ±0.005 - ±0.01mm. This is because the energy of electrical discharge is concentrated in an extremely small area, enabling precise removal of materials. For example, when machining tiny mold cavities or precision parts, it can well guarantee dimensional accuracy and shape accuracy to produce high-quality products. In the aerospace field, for some small and complex parts, EDM processing can exert its accuracy advantage.
- **Suitable for hard-to-machine materials**
- For extremely hard materials such as cemented carbide, hardened steel, and titanium alloy, traditional machining methods may face problems such as severe tool wear and low machining efficiency. However, EDM processing removes materials through electrical discharge and is not limited by material hardness. For example, in mold manufacturing, for some high-hardness mold steels after quenching treatment, EDM can easily process and create complex mold shapes.
- **Capable of machining complex shapes**
- It can process parts with complex shapes, such as various special cavities, narrow grooves, and irregularly shaped holes. It can machine inside workpieces or in areas that are difficult to reach by traditional machining methods. For example, in manufacturing injection molds, it can process cavities for forming the complex appearance and internal structure of plastic products, including some molds with undercuts or deep holes.
- **No cutting force in the machining process**
- Since EDM processing is based on the thermal effect of electrical discharge to remove materials, there is no mechanical cutting force between the electrode and the workpiece during the machining process. This is very beneficial for machining thin-walled and easily deformable parts. For example, when machining some miniature electronic component casings with very thin walls, it will not cause part deformation or damage due to cutting force, ensuring the integrity and accuracy of the parts.
2. **Disadvantages** - **Relatively low machining efficiency**
- Compared with traditional machining methods such as milling and turning, EDM processing is relatively slow. Especially when machining large-area and large-surplus workpieces, the machining time will increase significantly. This is because electrical discharge can only remove a small amount of material at a time, and the discharge frequency is also limited. For example, for a large mold blank, using EDM processing to remove most of the surplus may take a long time.
- **Electrode wear affects accuracy**
- During the EDM processing, the electrode will be worn. Electrode wear will lead to a decrease in machining accuracy, and it is necessary to frequently replace the electrode or repair the electrode. Especially when machining high-precision parts or complex structures such as deep holes and deep cavities, the influence of electrode wear on machining accuracy is more obvious. For example, when machining a deep cavity, as the machining depth increases, the wear at the end of the electrode may cause deviations in the size and shape accuracy at the bottom of the cavity.
- **Limited machined surface quality**
- Although EDM processing can achieve a certain degree of accuracy, the surface quality after machining is generally not as good as precision machining methods such as grinding. The machined surface will leave discharge pits, and the surface roughness is generally between Ra0.8 - Ra3.2μm. For some parts with extremely high surface quality requirements, such as optical lens molds, subsequent surface treatment processes such as polishing may be required to improve the surface quality.
- **High equipment cost and operating cost** - The price of EDM processing equipment is relatively expensive, and the maintenance and operation of the equipment require professional technicians and a specific working environment. At the same time, a large amount of electrical energy and electrode materials are consumed during the processing, which increases the processing cost. For example, the price of some high-precision EDM processing machines may reach hundreds of thousands of yuan or even higher. And during the processing, the cost of special electrode materials and electrical energy consumption are also a significant expense.