A study of methods for the magnetorheological finishing of glass panels for the inner screen of mobile phones

Abstract

In order to solve the problem that there are many scratches on the glass panels of the inner screen of mobile phones after chemical mechanical polishing (CMP), three different magnetorheological finishing (MRF) methods were investigated to polish the surface: 1) single-point MRF with static magnetic field; 2) cluster MRF with static magnetic fields; and 3) cluster MRF with dynamic magnetic fields, which turned out to be the most suitable one of the three. The rotation of a permanent magnet relative to the polishing disc generates dynamic magnetic fields, which have a positive effect on the polishing process and thus enable an ultra-smooth, scratch-free, high-quality surface on the glass panels required for the inner screen of mobile phones. Single-factor experiments were carried out to further adjust the key process parameters, such as machining time, machining gap, magnetic-pole speed, polishing-disc speed, and workpiece speed. An optimised parameter set of 20 min machining time, 1.0 mm machining gap, 120 r/min magnetic-pole speed, 60 r/min polishing-disc speed, and 400 r/min workpiece speed led to an improvement of the original surface roughness of a glass panel with scratches and pits from Ra 1.15 nm to Ra 0.45 nm, that is tantamount to an ultra-smooth surface.