Advances in ultrafast laser technology have created new opportunities for precision manufacturing, especially in fabricating micro-hole arrays. However, producing shaped micro-hole arrays remains challenging due to the demands for high precision, small size, and large quantities. This study aims to overcome these challenges by investigating a high-throughput drilling method for shaped micro-hole arrays. The research combines multi-beam parallel processing with helical drilling techniques to enhance efficiency and ensure high quality. This work is essential for significantly improving the production speed and consistency of micro-hole arrays, which are crucial in various industrial applications, including aerospace, electronics, and medical devices.

This study used a 900-fs, 1030-nm ultrafast laser with a Gaussian beam profile to process metal sheets (copper and stainless steel). The pulse energy and frequency for the experiments were 50?180 μJ and 100 kHz, respectively. The beam rotation speed was set at 4000 r/m, and the focal length of the focusing lens was 100 mm. A series of micro-holes with varying shapes in the depth direction were created on a metal plate using a self-built multi-system collaborative micro-hole processing platform. Optical microscope and scanning electron microscope were employed to analyze the shape variations of the micro-holes in the depth direction. The study examined the effects of the range and rate of dynamic changes in helical drilling parameters, as well as focal position, on hole shape. Additionally, the helical drilling system was integrated with multi-beam processing to assess the consistency of sub-beams and resulted hole shapes through simulations and processing experiments.

The study yielded several key findings, each supported by empirical data and simulations:

1) The geometric optics simulation revealed that rotating the beam before splitting achieves independent rotation of each sub-beam. Despite variations of 0.15 μm in rotation radius and ±0.29° in exit angle (Fig. 5), these had a negligible impact on hole shape consistency during actual processing (Fig. 7). This level of precision is crucial for applications requiring high fidelity in hole shape, such as jet engine components and precision filters.

2) Shaped micro-holes can be drilled using either staged or continuous adjustment of the helical drilling parameters. In the staged adjustment process, variations in these parameters directly affected the micro-hole shapes, while the laser focus position determined their depth distribution (Fig. 2). In the continuous adjustment process, the shape distribution was influenced by both the laser focus position and the rate of change in the helical drilling parameters (Fig. 4). This method allows for the creation of more complex hole shapes, which is advantageous for applications needing varied cross-sectional profiles.

3) The multi-beam helical drilling process showed high adaptability to various beam splitting configurations. Notably, even with a maximum sub-beam spacing of 1 mm, the processed hole shapes maintained consistent precision (Fig. 8). This adaptability is crucial for scaling the process to different sizes and configurations of micro-hole arrays, which is important for various industrial applications.

4) A key finding was the demonstration of high processing efficiency. Using the multi-beam helical drilling method, 2000 shaped micro-holes were processed in parallel with 16 beams on a 0.3 mm thick stainless steel plate. This approach achieved a processing efficiency more than ten times greater than traditional single-beam methods (Fig. 9).

Integrating multi-beam parallel processing with helical drilling techniques offers a viable solution to the challenges of manufacturing shaped micro-hole arrays. Both staged and continuous adjustment processes provide precise control over micro-hole shapes and depth distribution. Geometric optics simulations confirm that minor discrepancies in beam rotation parameters have minimal impact on hole shape consistency. Additionally, the multi-beam helical drilling process is highly adaptable, maintaining accuracy even with varying beam configurations. The observed more than tenfold increase in processing efficiency underscores the potential of the method for industrial applications and marks a significant advancement in the high-throughput production of micro-hole arrays. This research establishes a solid framework for efficient and precise fabrication of molded micro-hole arrays, demonstrating the advantages of combining multi-beam and helical drilling technologies. Future work can focus on further optimizing helical drilling parameters and adapting the technique to different materials and thicknesses to expand its application scope. Advances in real-time monitoring and feedback control can also enhance the precision and reliability of the process, making it an even more powerful tool for industrial microfabrication.