研究目的
To detect the manufacturing limits of the micro coining process for producing microstructured surfaces to reduce friction in lubricated contacts, focusing on achievable accuracy and failure analysis of cuboid and cylindrical microstructure elements.
研究成果
The micro coining process is suitable for manufacturing microstructured surfaces with defined accuracy. Key findings include the identification of aspect ratio as a critical failure criterion, with cuboid structures failing at aspect ratios above 1.13 and cylindrical structures up to 1.60. Geometrical deviations due to elastic springback and manufacturing tolerances were quantified, and the process shows potential for large-scale production integration, though further optimizations are needed for edge rounding and non-90° flank angles.
研究不足
The study did not investigate pin heights below 5 μm due to machine positioning accuracy limitations, and structures larger than 50 μm were not considered as they exceed Hertzian contact width. Edge roundness and pin height variations were not fully analyzed, and the process may be influenced by electrode wear and thermal factors. Future work could address lubrication effects and integration with extrusion processes.
1：Experimental Design and Method Selection:
The study involved manufacturing coining punches using micro electrical discharge machining (μEDM) and analyzing the micro coining process. The methodology included investigating accuracy and repeatability of μEDM for different geometries and dimensions, followed by coining to transfer microstructures onto workpieces. Geometrical deviations were analyzed due to their impact on tribological conditions.
2：Sample Selection and Data Sources:
Workpiece material was case hardening steel 1.7131, and coining punch material was high-speed steel 1.3343. Microstructures included cuboid and cylindrical geometries with widths/diameters from 5 μm to 50 μm and heights from 30 μm to 50 μm. Data were collected using laser scanning microscopy.
3：7131, and coining punch material was high-speed steel Microstructures included cuboid and cylindrical geometries with widths/diameters from 5 μm to 50 μm and heights from 30 μm to 50 μm. Data were collected using laser scanning microscopy.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included a Sarix SX-200-HPM μEDM machine, laser scanning microscope Keyence VK-X200, and a micro coining tool. Materials included steel 1.7131 and 1.3343, with electrodes made of carbide.
4：7131 and 3343, with electrodes made of carbide.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The process began with μEDM to create micro pins on punches, followed by coining with defined forces (e.g., 30 kN) to imprint structures. Measurements were taken using cross-sections and averaging techniques with specified magnifications and step sizes.
5：Data Analysis Methods:
Data were analyzed for deviations in width, diameter, and flank angle using statistical methods and software like Esprit CAM, with results presented in graphs and tables.
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