From a large number of experimental data, it can be seen that the microscopic process of each EDM/WEDM corrosion is a comprehensive process of electric field force, magnetic force, heat, hydrodynamics, electrochemistry, and colloidal chemistry. EDM/WEDM mainly relies on thermal expansion and local micro explosion to make molten and gasified metal materials thrown out for erosion.
WEDM is mainly used in mold manufacturing and is also widely used in the processing of templates, cams, forming tools, precision small parts, and special materials. In addition, in the trial production of motors, electrical appliances, and other products, some parts can be directly processed by wire cutting, which saves the time of manufacturing stamping dies and shortens the trial production cycle.
In addition to the basic characteristics of EDM/WEDM, EDM/WEDM has some other characteristics:
1. Any two-dimensional curved surface with a straight line as generatrix can be machined without manufacturing complex tool electrodes.
2. It can cut about 0.05mm narrow slit.
3. Not all surplus materials are processed into scrap during processing, which improves the utilization rate of energy and materials.
4. In the low-speed EDM/WEDM Process in which the electrode wire is not recycled, the continuous updating of the electrode wire is conducive to improving the machining accuracy and reducing the surface roughness
5. The cutting efficiency of EDM/WEDM is generally 20-60mm2 / min, and the maximum can reach 300mm2 / min; The machining accuracy is generally ± 0.01 - ± 0.02 mm, and the maximum is ± 0.004 mm; The surface roughness is generally R α 2.5 ～ 1.25 μ m, up to R α 0.63 microns; The cutting thickness is generally 40-60 mm, and the maximum thickness can be 600 mm.
1. Increase in processing power
The slow wire cutting process benefits from the appearance of nanosecond high peak current pulse power supply technology, and the continuous development and application of detection, control, anti-interference, and other technologies, so the processing power has been significantly improved. Compared with other processing methods, the slow wire cutting process can save about 30% to 50% of the processing time.
2. Perfect appearance quality
The non-electrolytic power supply is selected for the slow wire EDM/WEDM machining, which can control the thickness of the external metamorphosis layer below 2 microns. Compared with the traditional grinding process, the cutting edge of cemented carbide die processed by EDM/WEDM is not different in wear resistance, and even better than the former. Therefore, more and more parts are undergoing the technological innovation of "cutting instead of grinding".
3. Improvement of machining accuracy
The circuit accuracy, mechanical accuracy, pulse power supply accuracy, servo control accuracy, and other hardware capabilities of the slow wire cutting machine tool have been improved. With the support of this software and hardware, the accuracy of the slow wire cutting machining has reached a high level, reaching the order of 1 micron, and the tool setting accuracy can reach 2 microns. No matter in a dry or wet environment, the workpiece will not be damaged.
Using the slow wire cutting process, the machining accuracy of thick workpieces, small fillets, narrow slits, narrow grooves, and micro parts can be fully ensured.
It is mainly used to process various workpieces with complex shapes and fine precision. According to the running speed of the wire electrode, the wire EDM/WEDM machine tool is generally divided into two categories: one is the slow wire (also called the low-speed wire EDM/WEDM machine tool). The wire electrode moves in a low-speed unidirectional direction, generally, the wire speed is less than 0.2m/s, the accuracy is 0.001mm, and the surface quality is close to the grinding level. The processed surface is very smooth. Since the slow wire cutting machine adopts the method of continuous wire feeding by wire electrode, that is, the wire electrode completes the processing in the process of movement, even if the wire electrode is lost, it can be continuously supplemented, so the machining accuracy of parts can be improved. The surface roughness of the workpiece processed by the slow wire cutting machine can generally reach Ra = 0.8 μm and above, and the roundness error, linear error, and dimensional error of the slow wire cutting machine are much better than that of the fast wire cutting machine. Therefore, the slow wire cutting machine has been widely used in processing high-precision parts.
1. Wire speed. The wire speed of fast wire walking is greater than or equal to 2.5m/s, and the commonly used value is 6 to 10m / s, while the wire speed of slow wire cutting is less than or equal to 2.5m/s. The common value is 0.25 to 0.001m/s.
2. Working state of the electrode wire. The fast wire cutting machine tool is used repeatedly for reciprocating wire supply. The slow wire cutting machine tool is unidirectional and disposable.
3. Electrode wire material. The electrode wire material of a fast wire cutting machine is molybdenum wire and tungsten molybdenum alloy, while the electrode wire of a slow wire cutting machine is brass, copper, copper-based alloy, or plated material.
4. Working fluid. The working fluid of a fast wire cutting machine is an emulsion or water-based working fluid, while the working fluid of a slow wire cutting machine is deionized water, and kerosene is used in individual fields.
5. Accuracy. Although the research on slow walking wire started relatively late in China, the technology has been developed in teaching and research institutes such as the school of machinery of Huazhong University of science and technology, with an accuracy of 0.1um. The accuracy of the slow wire is greater than that of the medium wire and greater than that of the fast wire.
6. Cut surface finish. The fast wire has a poor finish, the middle wire is in the middle, and the slow wire has a high finish.
