MANUFACTURING METHOD OF GLASS SUBSTRATE FOR MAGNETIC DISK AND MANUFACTURING METHOD OF MAGNETIC DISK

PROBLEM TO BE SOLVED: To provide a polishing method, a polishing device, and so forth by which an inner peripheral end surface and/or an outer peripheral end surface of a glass substrate can be smoothly polished by simple method and device and high purification of the surface can be attained in a high level. SOLUTION: A manufacturing method of the glass substrate for a disk-shaped magnetic disk having a circular hole at a center part includes a step for chamfering the glass substrate, a step for polishing the end surfaces, a step for polishing principal surfaces and a step for performing chemical strengthening treatment in this order. In the step for polishing the end surfaces, a plurality of glass substrates are stacked, a polishing liquid containing a free abrasive is supplied to an inner peripheral end surface part and a polishing brush or a polishing pad which has a rotary shaft and is rotated and to which brush hairs are spirally implanted to be inclined to a plane perpendicular to the rotary shaft is brought into contact with the inner peripheral end surface part to polish a chamfered part and a side wall part. Thus the glass substrate for the magnetic disk having 10 to 25 kg flexural strength after chemical strengthening treatment is obtained. COPYRIGHT: (C)2008,JPO&INPIT