Analysis of Erroneous Zones in EDM Machining of Mould Enterprises

**1. Introduction** Electrical Discharge Machining (EDM) is a crucial process in mold making, playing a vital role in the production of injection molds. However, many mold companies still face challenges in their process levels, where errors often result in EDM parts failing to meet the required precision and efficiency standards. This article provides a detailed analysis of common misconceptions in EDM practices within die and mold manufacturing companies. **2. Common Misunderstandings in EDM** **2.1 Misunderstanding of Positioning Methods** The accuracy of EDM largely depends on precise positioning. In traditional Z-axis machining, the X and Y axes define the cavity position, while the Z-axis controls the depth. One commonly used method involves direct contact between the electrode and the workpiece (Figure 1), which is widely adopted due to its simplicity. However, for high-precision applications—such as the molding of plastic components like the Huff slider or the alignment of mold cores—this method may not be sufficient. The large contact area can introduce inaccuracies from burrs, debris, or misalignment of the electrode and workpiece. Even with clean surfaces, achieving an accuracy of 0.01mm becomes challenging. To address this, indirect positioning using reference balls (Figure 2) is often preferred. This method minimizes error by using point contact, ensuring more stable and accurate positioning, especially for complex or large workpieces. While direct contact is convenient for general use, it's important to recognize that for high-accuracy tasks, alternative methods are necessary. Using reference balls not only improves accuracy but also reduces setup time, particularly when multiple electrodes or workpieces are involved. **2.2 Misunderstanding of Electrode Material Selection** Choosing the right electrode material significantly impacts the EDM process. Materials such as copper, graphite, and copper-tungsten alloys each have unique advantages and limitations. Many mold companies tend to use the same material for all electrodes without considering the specific requirements of each job. Copper is known for its good conductivity and stability during finishing, but it has a low melting point and is unsuitable for high-current operations. Graphite, on the other hand, is ideal for large-area roughing and offers high-speed processing, though it may suffer from instability during finishing. Copper-tungsten alloys, while expensive, provide excellent wear resistance and are suitable for high-precision applications. Selecting the appropriate material requires understanding the trade-offs between cost, performance, and application needs. For example, in high-precision molds, the cost of the electrode material may be less of a concern compared to achieving the desired surface finish and dimensional accuracy. **2.3 Mistakes in the Selection of Electrode Scaling** Electrode scaling refers to adjusting the size of the electrode to account for the spark gap during EDM. Proper scaling is essential for achieving the desired dimensions, surface quality, and processing speed. However, many companies use fixed scaling values without considering the specific characteristics of the workpiece. For instance, a standard scaling of 0.2 mm on one side for roughing and 0.07 mm for finishing may not be optimal for large or complex parts. Larger electrodes may require larger scaling to allow for higher discharge parameters, improving efficiency. Conversely, for high-precision parts, smaller scaling is needed to ensure accuracy after polishing. Understanding how different materials, part geometry, and machining conditions affect scaling is key to optimizing the EDM process. **2.4 Mistakes in Process Methods** Many mold companies continue to rely on traditional EDM techniques, even as CNC EDM machines become more advanced. These machines offer features like horizontal machining and multi-axis linkage, which can greatly improve efficiency and quality. For example, using a Z-axis for deep, narrow cavities can lead to unstable discharges and slow processing. By utilizing horizontal servo functions, operators can achieve faster and more consistent results. Similarly, diagonal machining can prevent discharge instability in small areas, such as when removing tool radius corners. Embracing modern EDM technologies and process improvements can help companies stay competitive and meet the growing demands of the industry. **3. Conclusion** In today’s fast-paced manufacturing environment, mold companies must continuously adapt and innovate. Many still rely on outdated methods and lack awareness of new technologies, which hinders overall progress. By addressing common misconceptions in EDM—such as positioning, electrode material selection, scaling, and process methods—companies can enhance both efficiency and quality. With advancements like CNC EDM machines, rapid clamping systems, and mixed powder processing, the potential for high-efficiency and high-precision manufacturing is greater than ever. Mold enterprises should tailor their processes to their specific needs and remain committed to continuous improvement to stay ahead in the market.

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