Understanding the Machining Process of Hierarchical Micro/Nanograting Structures Used for Optical Variable Device

Abstract Hierarchical micro/nanograting structures have attracted increasing attention owing to their significant applications in the fields of structural coloring, anti-counterfeiting, and decoration. Thus, the fabrication of hierarchical micro/nanograting structures is important for these applications. In this study, a strategy for machining hierarchical micro/nanograting structures is developed by controlling the tool movement trajectory. A coupling Euler-Lagrange finite element model is established to simulate the machining process. The effect of the machining methods on the nanograting formation is demonstrated, and a suitable machining method for reducing the cutting force is obtained. The height of the nanograting decreases with an increase in the tool edge radius. Furthermore, optical variable devices (OVDs) are machined using an array overlap machining approach. Coding schemes for the parallel column unit crossover and column unit in the groove crossover are designed to achieve high-quality machining of OVDs. The coloring of the logo of the Harbin Institute of Technology and the logo of the centennial anniversary of the Harbin Institute of Technology on the surface of metal samples, such as aluminum alloys, is realized. The findings of this study provide a method for the fabrication of hierarchical micro/nanograting structures that can be used to prepare OVDs.