Wire EDM Cutting Revealed: Role in Modern Manufacturing
Table of Contents
What Is Wire EDM Cutting?
Wire cutting, also called wire EDM( Electrical Discharge Machining) cutting technology is a metal processing technique, also known as wire cutting machine tool machining, which is a process method that uses linear electrodes for electrical discharge machining. It cuts through pulse discharge between the electrode wire and the workpiece, and is suitable for processing various conductive materials, especially in the field of precision machining.
The Principle and Processes Of Wire EDM Cutting
The Principle
Wire EDM cutting is a technology that uses electric discharge to cut metal. This technology controls the distance between the electrode and the material being cut within a certain range, and applies high-frequency voltage to form electric spark discharge between the electrode and the workpiece, causing the surface of the workpiece to melt and oxidize, and forming bubbles between the electrode and the workpiece. The electric spark discharge formed alternately between the electrode and the workpiece continuously peels off the surface material of the workpiece, thereby achieving cutting.
The Processes
The wire EDM cutting process can be divided into three stages.
- Arc formation between electrode and workpiece: In online cutting, a thin and conductive metal wire is used as the electrode. The distance between the electrode and the workpiece is very small, but there is no direct physical contact. By applying high voltage, an arc discharge is formed.
- Arc generates high temperature and high pressure areas: The energy generated by arc discharge is very high, causing the metal on the surface of the workpiece to be instantly heated to a high temperature state. This high-temperature and high-pressure area can cause evaporation and corrosion on the metal surface.
- Metal corrosion and removal: In high-temperature and high-pressure areas, metals will begin to corrode and dissolve. Corrosive metal particles are washed away by shock waves, thereby achieving the removal of metal workpieces. The arc continuously moves between the electrode and the workpiece, enabling the entire cutting process to form the desired shape on the metal surface.
The material removal during wire cutting processing occurs due to the influence of sparks on the surface of the workpiece. These sparks are not continuous currents, but brief currents that occur millions of times per second.
The Features For Wire EDM Cutting
- Wire EDM Cutting can cut conductive materials and semiconductor materials with high hardness, strength, brittleness, and toughness that are difficult or impossible to process using traditional methods.
- Due to the extremely thin electrode wire, it can process small irregular holes, narrow gaps, and complex shaped parts.
- The surface of the workpiece being processed is minimally affected by heat, making it suitable for processing thermal sensitive materials in factories. Meanwhile, due to the concentration of pulse energy in a very small range, the machining accuracy is high.
- During the machining process, there is no direct contact between the tool and the workpiece, and there is no significant cutting force.
- Due to the thin cutting seam and the fact that only the workpiece is subjected to contour machining, the actual amount of metal erosion is very small, resulting in a high utilization rate.
- Compared with electric discharge forming, using wire electrodes instead of forming electrodes eliminates the design and manufacturing costs of forming tools and shortens production preparation time.
The Differences Between Wire EDM Cutting And Conventional EDM
Different principles
Both wire EDM cutting and electrical discharge machining（EDM）are metal cutting equipment based on the principle of electrical discharge machining, but their principles have certain differences.
Wire cutting is the use of electrode wires as cutting tools to perform submerged cutting on workpieces. By continuously moving the electrode wires downwards, various shapes and sizes of the workpiece are cut. The wire EDM cutting machine generates electric spark discharge on the surface of the workpiece, and removes the metal material on the surface of the workpiece through discharge ablation, thereby achieving cutting.
Different suitable materials
There are also certain differences in the scope of application between wire cutting and conventional EDM.
Wire cutting is suitable for cutting various metal materials, especially for workpieces with high hardness. Wire cutting can achieve high-precision and fast cutting effects. The EDM cutting machine is suitable for cutting all kinds of conductive materials, including metals, alloys, ceramics and other materials, and can achieve high-precision cutting effect.
Different processing effects
There are also differences in machining effects between wire cutting and electric discharge machining.
Wire cutting can achieve high-precision machining results, especially adept at making small and complex parts. The machining effect of electric discharge machining is also very accurate, but it cannot cut small inner holes and complex shapes.
Different usage environments
There are also differences in the usage environment between wire cutting and electric discharge machining.
Wire cutting usually needs to be carried out in a nitrogen or other inert gas environment to prevent oxidation generated by discharge from contaminating the cutting surface. Electric discharge machining require cutting in oil or other insulating media to prevent short circuits between electrode wires and workpieces.
The Applications For Wire EDM Cutting
Wire EDM cutting is widely used in various fields of manufacturing. For example, fields such as automobile manufacturing, aerospace, electronics, molds, medical equipment, precision instruments, etc.
- Mold manufacturing: Wire cutting can be used in the mold manufacturing industry to quickly and accurately cut complex shaped metal and non-metal materials.
- Mechanical manufacturing: Wire cutting is suitable for various mechanical manufacturing industries and can efficiently and accurately manufacture various workpieces and parts.
- Jewelry: Wire cutting processing can be used for the production of jewelry, which can accurately cut and polish various gemstones and metal materials.
- Electronic devices: Wire cutting processing can be used in the electronic device industry, such as cutting chips, electronic circuit boards, etc.
The Development Status of Wire EDM Cutting Machines in China
Wire Cutting Machine are divided into two types based on the different wire speed and motion mode: high-speed reciprocating wire cutting electric discharge machine (hereinafter referred to as “fast wire cutting machine “) and low-speed unidirectional wire cutting electric discharge machine (hereinafter referred to as “slow wire cutting machine”)
The Development of High Speed Wire EDM Cutting Machine
The fast wire cutting machine is a unique electrical machining machine in China. After forty to fifty years of development, the technology has become quite mature and occupies an important position in China’s machinery manufacturing industry. It is also the main model currently produced in China, with its biggest advantages being simple structure, easy operation, low cost of use, and high processing efficiency, with good cost-effectiveness.
The electrode wire of the fast wire cutting machine performs high-speed reciprocating motion, with a wire speed of 8-10 m/s. The electrode wire can be reused during the machining process, and the diameter range of the electrode wire is 0.12-0.25 mm, with a diameter of 0.18 mm being the most commonly used; The surface roughness of the processed material can reach R α: 3.2-1.6 μ m, with the optimal value being only 1 μ m; Controllable machining accuracy of 0.01-0.02mm.
Due to factors such as rapid electrode wire loss, poor rigidity of the host structure, large influence of temperature changes in the processing environment, unstable accuracy, open-loop control feed system, and changes in the conductivity of the working fluid over time, the machining accuracy of the wire cutting machine is limited.
In recent years, domestic manufacturers of high-speed wire cutting machine have made significant progress in improving the accuracy of reciprocating wire cutting machine(mainly positioning accuracy and repeat positioning accuracy) and the surface quality of machined parts as two breakthrough directions for product development. Significant progress has been made in host manufacturing technology, pulse power technology, control technology, processing technology, and other aspects.
Development of Unidirectional Low Speed Wire EDM Cutting Machine
The electrode wires of low-speed wire cutting electric discharge machines (unidirectional slow wire cutting) perform low-speed unidirectional motion, and the wire cutting speed is generally not higher than 0.2 m/s; During the processing, the electrode wire is discarded after one use, and the tensile strength requirement is not high. The electrode wire material is generally galvanized copper wire or brass wire with a diameter range of 0.03-0.35 mm. When the productivity is high, galvanized brass wire with a diameter of less than 0.3 mm can be used for processing. The surface roughness of the processed material can generally reach R α: 1.6-0.2 μ m, and the controllable processing accuracy is 0.005-0.002 mm.
The main characteristics are: due to the unidirectional movement of the electrode wire, one-time use, uniform tension, and low vibration, the processing stability, surface roughness, and accuracy indicators are superior to those of fast wire cutting machines.Unidirectional slow wire cutting was originally the main model produced and used abroad. China started relatively late in the research of slow wire cutting machine tools.
The main characteristics are: due to the unidirectional movement of the electrode wire, one-time use, uniform tension, and low vibration, the processing stability, surface roughness, and accuracy indicators are superior to those of fast wire cutting machines.Unidirectional slow wire cutting was originally the main model produced and used abroad. China started relatively late in the research of slow wire cutting machine tools.
However, in recent years, with the support of national special funds, Chinese researchers and enterprises have invested a large amount of research and development efforts, and have now completed the research and development of a new generation of slow wire cutting machine tools.
Conclusion
As an important processing method in modern manufacturing, wire EDM cutting has the characteristics of high precision, fast processing speed, and large processing thickness, and is an indispensable part of modern manufacturing. In the future development process, wire cutting will gradually achieve higher efficiency and higher processing quality, becoming an important role in the manufacturing production process.
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