Mar 19,2026
Processing Strategies for Mold Fine Structures: From Fine Fresing to Fine Electric Sparks
Processing Strategies for Mold Fine Structures: From Fine Fresing to Fine Electric Sparks
Micro machining, Micro milling, Micro EDM, High-speed cutting, Precision mold
With the miniaturization of electronic products and the sophistication of medical devices, micro-structures (such as pores, grooves, tendons, and teeth) in molds have become increasingly common. These features often range in size from tens to hundreds of microns, with a commensurate requirement of ±2-5 μm and a Surface roughness of Ra 0.1 μm or less. Processing such micro-structures poses extreme challenges for machines, tools, processes, and detection. Micro-processing technologies have become the core competitiveness in precision molds manufacturing.
Micro milling is the main means of processing three-dimensional micro-structures. It uses micro vertical milling blades with diameters as small as 0.1 mm or even 0.03 mm, processed on high-speed milling machines (with main axis rotational speeds up to 30,000–60,000 rpm). The key to micro milling is the matching of the blade‘s rigidity and cutting parameters. Blades have extremely small diameters, extremely poor rigidity, and are extremely breakable. Therefore, minimal input per tooth (typically 1–5 μm/z) and minimal cutting depth (a few microns to dozens of microns) must be adopted, while maintaining stable sawdust load. Blade materials are often made from ultra-fine crystalline hard alloys or single-crystal diamonds. Cooling lubrication is also crucial, often using micro lubrication (MQL) or an oil-gas mixture to avoid blade wear or artifact burns due to cutting heat accumulation.
Micro Electrical discharge machining is a powerful tool for processing fine structures in high-hardness materials. When the material to be processed is extremely hard (such as hard alloys, powdered high-speed steel), or when the structure shape is too complex (such as deep and narrow grooves, heterogeneous holes), micro milling often fails. In this case, Micro Electrical discharge machining (Micro EDM) becomes the preferred choice. It utilizes extremely thin electrodes (which can be processed to a diameter of less than 0.05 mm) for discharge machining, with no macroscopic cutting force, regardless of the hardness of the material. Micro Electrical discharge machining includes micro cavity machining (using molded electrodes) and micro perforation (using silk electrodes or rod electrodes). The difficulty lies in the manufacturing of the electrodes and the compensation of wear. The electrodes themselves need to be prepared through fine abrasion or wire electrode discharge abrasion (WEDG) technology. During the processing process, the discharge status needs to be monitored in real time and electrode wear is automatically compensated to ensure size accuracy.
Laser microprocessing is an emerging complementary technology. For certain special materials (such as ceramics, diamonds) or micro-structures that require contactless, heat-free areas of impact, fly-second laser or skin-second laser processing shows unique advantages. The laser can focus on micrometer-scale specks of light and achieve high-precision removal by burning the material. It has no knife wear, can process any hard brittle material, and has minimal heat-impact areas. However, laser processing is relatively inefficient and sensitive to material reflectivity, and is currently mainly applied to specific situations, such as micro-textured surfaces of molds, and micro-porous processing.
The detection of fine structures is the final hurdle in ensuring quality. Traditional contact measurements cannot be used for fine structures, as the head measurement itself may be larger than the feature size. Therefore, non-contact measurement methods must be adopted. High-precision optical microscopes, laser co-focus microscopes, white light interferometers, and scanning electron microscopes (SEM) are the main tools for fine structure detection. They can provide 3D shape and size information at the micrometre or even nanometre level, helping engineers validate processing results.
Environmental control for microprocessing is crucial. Microprocessing is extremely sensitive to temperature, humidity, vibration, and cleanliness. Processing plants typically require constant temperature (±0.5°C), constant humidity (±5%), vibration resistance (through ground insulation), and cleanliness at level 100. Any slight environmental fluctuation can affect processing accuracy.
Mastering microprocessing technology means that mold manufacturers can dabble in high-value-added fields such as optical communication connectors, microelectronic packaging, microflow-controlled chips, and precision medical devices. This is a cutting-edge technology that combines precision mechanics, optics, electronics, and material science, and is a passport for mold manufacturing to advance into the microscopic world.
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