Ultra-precision milling and grinding for large-sagittal MgF₂ aspheric optical elements

Ultra-precision machining for large-sagittal aspheric optical elements has become one of the research hotspots in the world’s processing and manufacturing field in recent years. This paper mainly studies the processing of large-sagittal MgF₂ aspheric optical components, analyzes the grinding tracks of two different grinding methods, and seeks the best grinding method. Experimental research was carried out on three milling modes in the rigid grinding process. In the processing method of pressed milling, the rotational speed of the workpiece has the most significant effect on the surface roughness. The surface roughness Ra can be reduced by reducing the grain size of the grinding wheel and adjusting the processing parameters. Through the cylindrical milling method, the surface roughness Ra measured with the D46 grinding wheel in the direction of rotation can reach the minimum, which is 0.7–0.8 μm. In the fine grinding stage, the circumferential grinding and endface grinding models are established, and the simulation analysis and experimental verification of the trajectory of the abrasive particles in the two grinding methods are carried out. The comparison shows that with endface grinding, the surface of the component is removed evenly in both directions. When the grain size is 28 μm, the surface roughness Ra_∥ and Ra_⊥ of face grinding are the smallest. Among them, Ra_∥ is 0.0458 μm, and Ra_⊥ is 0.0369 μm. This study is of great significance in improving the machining efficiency and accuracy of large-sagittal aspheric optical elements.