Mid-spatial frequency micro-waviness on machined surfaces by ultra-precision fly-cutting

Ultra-precision fly-cutting is an important ultra-precision processing technique and the ultra-precision milling machine with big fly-cutting pan fixed can produce optical components with large diameter, the machined surface of which is high in profile accuracy and low in surface roughness. However, mid-spatial frequency micro-waviness (spatial period from 100μm to 300μm and amplitude below 0.1μm), which is common on machined surfaces, has great impact on the performance of optical components. The stability of the axes orientation of gas journal spindles has great effect on the cutting precision, especially when the cutter is fixed on the outer edge of the big fly-cutting pan. Euler's dynamic equations were proposed for angular displacement calculation of gas journal spindles, and the analytic solution of the equations was deduced, so that the movement rule of spindles and its influence on the mid-spatial frequency micro-waviness are concluded and verified with tests. Finally the engineering approach was put forward to restrain the mid-spatial frequency micro-waviness on machined surfaces.