Manufacturing Materials for Modern Injection Molds: A Comprehensive Guide

In modern manufacturing, precision molds play a crucial role. From electronic product casings and automotive components to fine parts in household appliances, the quality of molds directly affects the appearance, performance, and lifespan of products. During the mold manufacturing process, Electrical Discharge Machining (EDM) stands out as an essential key technology, thanks to its "non-contact processing" and "high precision" characteristics. EDM can handle the machining of high-hardness and hard-to-cut materials while also achieving high-precision contouring of complex shapes.

In industries with extremely high detail requirements, such as the mold production for GK figures, EDM's role is even more prominent. GK figures are high-precision resin models originating from Japan, requiring an extraordinary level of detail. Their molds must handle a large number of fine details and complex curves. The precise control capabilities of EDM allow it to achieve these requirements without compromising material integrity, significantly improving mold quality and efficiency.

2. Principles and Characteristics of Electrical Discharge Machining

1. Basic Working Principle of EDM

The working principle of EDM is straightforward: by applying pulse currents between an electrode and a workpiece, electrical discharges are generated, causing localized melting and vaporization of the material, which is then removed. Since the electrode does not directly contact the workpiece, this "non-contact processing" characteristic enables the machining of high-hardness and brittle materials while avoiding wear and tear on traditional cutting tools.

2. Key Features of EDM

• Non-contact Processing: Unlike traditional cutting, milling, and grinding, EDM processes material using electrical discharges, which are not limited by the shape of the tool, making it suitable for complex shapes and thin-walled parts.
• Ability to Process High-Hardness Materials: EDM can easily process hardened steel, carbide, and other high-hardness materials that are difficult to machine using traditional methods. For the manufacturing of automotive molds, household appliance molds, and other high-hardness mold components, EDM is the ideal solution.
• High Precision and Surface Quality: EDM can achieve sub-micron-level machining accuracy, and its surface roughness can reach a high degree of smoothness (Ra 0.1–0.2 ?m), reducing the need for subsequent polishing processes.

3. Typical Applications of EDM in Modern Mold Manufacturing

1. High-Precision Detail Machining of Injection Molds

The surface finish of injection molds directly impacts the appearance of injection-molded products. When processing complex mold curves and fine texture details, EDM significantly improves the mold's surface quality, reducing the need for subsequent polishing. For example, products like smartphone casings and protective shells of electronic devices have high requirements for surface smoothness and detail clarity, where EDM technology plays a crucial role.

2. Cavity and Complex Groove Machining of Stamping Molds

Stamping molds often contain cavities, grooves, and irregularly shaped holes that require high-precision machining. EDM excels in the manufacturing of such molds, especially in the machining of deep cavities and complex-shaped surfaces. It can easily handle irregular geometries, ensuring high precision and surface quality.

3. Processing of High-Hardness Materials for Die-Casting Molds

Die-casting molds are usually made of high-hardness mold steel, which has a complex shape and large size. Traditional machining methods are time-consuming and labor-intensive when processing these materials. EDM not only enables the machining of high-hardness materials but also ensures efficient processing of large-sized molds, significantly reducing production time.

4. Fine Complex Contour Forming of Anime Figure Molds

In the production of anime figure molds, precise small details and high-gloss curved surfaces are essential. The production of GK figure molds often requires intricate sculpting of character facial expressions and clothing folds, which is where EDM's advantages come into play. EDM technology achieves these details with precision while maintaining material integrity, significantly enhancing mold quality and reproducibility.

4. Comparison and Advantages Over Traditional Machining Methods

1. Comparison with Cutting Machining

• Ability to Process High-Hardness Materials: Traditional cutting, milling, and grinding require tools that are limited by their hardness, making it difficult to machine high-hardness materials. EDM, on the other hand, can easily process materials like hardened steel and carbide.
• Flexibility in Processing Shapes: Traditional cutting requires rotating tools, which makes it difficult to process irregular surfaces, while EDM can easily handle complex cavities and deep grooves.

2. Comparison with Laser Processing

• Processing Depth and Precision: Laser processing is excellent for surface treatment, but for deep cavity machining and parts with high depth-to-width ratios, EDM has a clear advantage.
• Material Removal Method: Laser uses high temperatures to melt and vaporize materials, which can cause thermal stress on the workpiece surface. In contrast, EDM uses "cold machining," ensuring that the surface of the workpiece is not affected by thermal stress.

5. Advances and Trends in EDM Technology

1. Digitization and Automation of Processing Units

Modern EDM equipment has widely adopted CNC (Computer Numerical Control) systems, enabling multi-axis machining and significantly improving automation. By integrating intelligent control systems, factories can operate 24/7, increasing productivity and production flexibility.

2. Advances in Electrode Materials

Electrode materials have a significant impact on EDM processing efficiency and surface quality. The emergence of new materials such as copper electrodes, graphite electrodes, and composite electrodes has enabled faster EDM processing speeds, reduced electrode wear, and further lowered production costs.

3. Rise of Hybrid Processing Technologies

EDM technology is no longer used in isolation. Instead, it is now combined with ultrasonic machining, laser processing, and high-speed milling to form "hybrid processing technologies," further expanding its machining capabilities and applicable scenarios.

6. Case Studies and Practical Insights

Case 1: Manufacturing of a Stamping Mold for an Automotive Component

• Objective: To machine irregular cavities and deep grooves in a stamping mold for an automotive part.
• Solution: Use EDM for deep cavity machining to reduce tool changes and lower costs.
• Results: Compared to traditional cutting methods, EDM reduced processing time by 30% and improved surface smoothness to Ra 0.2 ?m.

Case 2: Fine Contour Machining of a GK Figure Mold

• Objective: To process fine facial details and clothing features of a GK figure.
• Solution: Use a CNC EDM machine combined with high-precision electrodes for contour shaping.
• Results: The mold's micro-features were clearly defined, and subsequent polishing was reduced by 40%.

7. Conclusion

Electrical Discharge Machining (EDM) has become increasingly important in modern precision mold manufacturing. Its "non-contact processing, high precision, and ability to process high-hardness materials" make it indispensable in various mold manufacturing processes, especially in automotive, electronics, and household appliance industries. With the advancement of automation, digital control, and material technology, EDM will continue to develop towards higher precision, lower costs, and greater automation, providing strong support for the comprehensive upgrade of the manufacturing industry.