Optical parts nano-machining through innovative magnetic float polishing process

Optical components play a pivotal role in precision industries; however, conventional polishing methods often struggle to achieve nano-level finishing. The increasing demand for nano-scale precision in optical components has led to the exploration of novel processes such as Magnetic Float Polishing (MFP). This paper addresses the research gap concerning the application of MFP for polishing plano-optical windows (POW) and reveals the complex dynamics governing MFP. This innovative method eliminates workpiece clamping forces and using passive magnetic levitation as well as control mechanisms such as hydrodynamic lift force to achieve nanoscale roughness. Parameters such as fluid flow speed, viscosity, and density of the magnetic abrasive fluid (influenced by magnetic particle volume fraction), as well as hydrodynamic forces, have been controlled during the process on the POW. Finite Element Analysis simulations illustrated that impeller rotation speed and magnetic particle volume fraction are key parameters influencing hydrodynamic forces. The vertical component of the hydrodynamic force, known as the normal force, is also affected by the distance between the workpiece and impeller, while the passive magnetic levitation force is influenced by the distance between the workpiece and the vessel bottom. It was discovered that the magnitude of the normal forces significantly affects surface roughness; to minimize surface roughness, the normal hydrodynamic forces must be optimized within a specific range. This study introduce the hydrodynamic lift forces of the abrasive fluid as a predictive mechanism to optimize the normal forces, achieving minimum surface roughness around 26 nm Ra.