Development of High-precision Micro EDM System
Medical Devices,Medical Device Profile,Aluminium Profle Medical Device,Medical Device Aluminium Profle Jiangsu Yuejia Metallic Technology Co.,Ltd , https://www.yuejiametal.com
**Abstract:**
A micro EDM system has been designed and developed to address the challenges of precision machining at the micro-scale. The system integrates a horizontal-axis V-shaped ceramic support rotating spindle, a macro and micro servo feed system utilizing piezoceramics, a tool electrode copying system, a reading microscope, and an electrical control unit. This advanced setup enables high-precision machining of micro-components. The system has successfully produced micro-shafts with diameters as small as 4.5 μm and micro-holes with diameters down to 8 μm, demonstrating its effectiveness and reliability in microfabrication applications.
**Keywords:** Microfabrication; EDM; Piezoelectric Ceramic; Micro Shaft; Micro Hole
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**1. Features of Micro EDM**
Although the basic principle of micro EDM is similar to that of conventional EDM, there are several key differences due to the scale of the operation. The surface quality in micro EDM is primarily influenced by the size and depth of the craters formed during each discharge pulse, which is directly related to the energy of the pulse. Additionally, the machining accuracy depends on factors such as the discharge gap, process stability, and electrode wear.
Micro EDM operates using a pulsed power supply, where high-frequency discharge energy is delivered to the gap between the electrode and the workpiece. This energy generates high temperatures, leading to material removal through thermal effects. However, due to the extremely small size of the holes or features being machined—typically ranging from less than 5 μm to 100 μm—special requirements must be met to ensure dimensional accuracy and surface quality.
The main characteristics of micro EDM include:
**(1) Small Discharge Area**
The electrode used in micro EDM typically ranges from 5 to 100 μm in diameter. For electrodes smaller than 5 μm, the discharge area can be as small as 20 μm². Such a limited area makes it difficult to distribute discharges evenly, leading to instability and challenges in maintaining consistent processing.
**(2) Low Single-Pulse Energy**
To achieve precise material removal, the energy per discharge pulse must be carefully controlled. Typically, this energy should be between 10â»â¶ and 10â»â· J, or even lower, to ensure that the material removed per pulse is within the range of 0.01 to 0.10 μm.
**(3) Small Discharge Gap**
EDM is a non-contact process, and the discharge gap between the electrode and the workpiece varies depending on the conditions. In micro EDM, the gap is usually very small, often less than 1 μm. Controlling this gap is critical for achieving stable and accurate machining, especially when drilling micro-holes.
**(4) Difficulties in Tool Electrode Preparation**
Producing and installing micro-electrodes is a major challenge in micro EDM. Traditional methods often involve secondary mounting on the machine tool, which introduces errors in alignment and verticality. The use of wire electrode grinding (WEDG) has helped overcome these issues, allowing for more precise electrode fabrication and better system performance.
**(5) Challenges in Chip Removal and Spark Stability**
Due to the small discharge area and gap, short circuits are common in micro-hole machining. A highly sensitive feed servo system is required to quickly adjust the electrode position in case of abnormal discharges, ensuring stable spark conditions and improving overall efficiency.
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**2. Overall Design of the Micro EDM System**
Based on a thorough analysis of the characteristics of micro EDM, a prototype system was developed, integrating both mechanical and electrical components. The mechanical part includes a horizontal-axis V-shaped ceramic support rotating spindle, a macro-micro servo feed system using piezoceramics, a micro-tool electrode copying system, and a reading microscope.
The design incorporates a horizontal layout to improve chip removal and reduce the impact of gravity, making it ideal for deep and narrow hole machining. The system also uses a high-precision V-shaped ceramic support for the spindle, ensuring excellent rotational accuracy and stability. The combination of a DC motor for rotation and a piezoceramic-driven feed mechanism allows for precise and rapid movement.
The electrical control system is based on a single-chip microcomputer, providing real-time monitoring and control of the entire process. It includes a low-voltage micro-pulse power supply, circuitry for discharge state detection, and feedback mechanisms to ensure reliable and accurate machining.
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**3. Micro EDM Machining Experiment**
To evaluate the performance of the system, experiments were conducted on micro-shafts and micro-holes. The system successfully produced a micro-shaft with a diameter of 4.5 μm and a micro-hole with a diameter of 8 μm. These results demonstrate the system’s ability to achieve high-precision micro-machining, meeting international standards in the field.
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**4. Conclusion**
This study presents a comprehensive micro EDM system designed to meet the demands of microfabrication. With its innovative design, including a horizontal-axis V-shaped ceramic support, piezoceramic-based servo system, and advanced control mechanisms, the system has achieved remarkable results in machining micro-components. The successful production of micro-shafts and micro-holes confirms the system's capability and potential for further development in micro-EDM technology.