To increase a polishing speed and grind the whole of the surface of a glass disc with an uniform margin by a method wherein both surfaces of a glass disc further increased in thickness are simultaneously polished and a polishing method is made suitable for the glass disc for a magnetic recording medium.
The both surfaces of the surface and the back of a glass disc having an outer periphery with a diameter D1 of 65 mm and an inner periphery with a diameter D2 of 20 mm are pressed in a nipped state against a pair of rotary polishing bodies 2a and 2b for simultaneous polishing. In a polishing method described above, the glass disc is held by a vertical attitude holding means 4 and the glass disc is forcibly rotated, and polishing is executed by using a rotary polishing body with a diameter D of, for example, 70 mm (having a relation of D>D1-D2) having a rotary axis paralleling the rotary axis of the glass disc, the rotary polishing device serving as a pair of the rotary polishing bodies 2a and 2b.
SUZUKI KOICHI
SUGANO ATSUYA
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