Vibrating tools carve custom functional surfaces with precision and flexibility

In International Journal of Extreme Manufacturing, researchers at Tsinghua University have introduced a novel tip-based vibration carving (TVC) methods to create tiny and custom-shaped bumps, known as convex microstructures, on material surfaces. These structures can change how a surface interacts with environments, making them important in applications such as heat exchangers, anti-icing coatings, sensors, and water-repellent materials.

Such structures are common in nature. Plant leaves, insect wings, and fish scales all have small surface features that help control friction, guide water, or manage heat transfer. Scientists and engineers have tried to make similar structures on man-made surfaces, but it has been difficult to achieve high precision, diverse shapes, and fast processing at the same time. This has limited the flexibility needed for more advanced surface design.

To bridge that gap, this novel TVC methods combines two previously separate ideas: using a sharp tool tip to carve very small features, and vibrating the tool at high speed to increase throughput. During processing, the tool tip vibrates parallel to the material surface. With each vibration cycle, a small amount of material is removed or pushed aside, leaving behind a tiny bump.

By changing the vibration path, the researchers created three different bump shapes that resemble rhomboids, cones, and shells. These shapes can also be combined in any pattern, instead of being repeated in a uniform way, and offer more design freedom.

To help users apply the technology, the team developed a mathematical model that predicts how the final shape will change when different process settings, such as vibration amplitude or carving speed, are adjusted. They confirmed the accuracy of the model through simulation and machining experiments.

Tests showed that the TVC method works well on soft plastic materials and still performs effectively even when the tool becomes worn. The processed surfaces also showed signs of grain refinement beneath the carved area, suggesting a potential strengthening effect. After a simple surface treatment, the textured samples became highly water-repellent, with water droplets forming contact angles greater than 150 degrees.

"We hope this method gives engineers more freedom and efficiency when designing functional surfaces," said Prof. Jianjian Wang, the study's corresponding author. "Surface performance does not only depend on how smooth it is. With suitable micro-shapes, surfaces may gain abilities that they did not originally have."

Looking ahead, the team plans to explore more complex vibration paths to produce an even wider range of surface shapes. They believe TVC could be applied in areas where control of surface-environment interaction is critical, including thermal management, sensing, microfluidics, and optical devices.

International Journal of Extreme Manufacturing (IJEM, IF: 21.3) is dedicated to publishing the best research related to the science and technology of manufacturing functional devices and systems with extreme dimensions (extremely large or small) and/or extreme functionalities

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