Tooling calibration of secondary aspheric workpiece position in magneto-rheological polishing

In recent years, the magneto-rheological polishing as a deterministic processing method has become an essential way to obtain the high-precision aspheric surfaces. Take the rotationally symmetric secondary paraboloid as an example, the theoretical method of using the polishing wheel to calibrate the workpiece position in magneto-rheological polishing was analyzed, and the experimental verification was carried out on a Φ 230 mm fused quartz workpiece. The workpiece position was calibrated with less than 3 times of adjustment in the X direction and Y direction, respectively, and the offset in both X direction and Y direction was lower than 0.009 mm, respectively. The surface polishing experiment was conducted by magneto-rheological polishing technology on the workpiece, and the root-mean-square (RMS) of surface shape was converged from λ/7 to λ/40 after processing. The experimental results show that the proposed tooling calibration method of aspheric workpiece position is simple and reliable, which can accurately locate the workpiece and conducive to magneto-rheological polishing processing for high-precision aspheric surface.