Patent ID: 8640497

Claim:
A magnetic-disk glass substrate manufacturing method comprising a chemical strengthening step of bringing a disk-shaped glass substrate formed with a circular hole in its center into contact with a chemical strengthening treatment solution of one of a plurality of chemical strengthening treatment baths to exchange part of ions contained in said glass substrate for ions in said chemical strengthening treatment solution, thereby chemically strengthening said glass substrate, said method further comprising: an inner diameter measuring step of measuring an inner diameter of said glass substrate before said chemical strengthening step; a grasping step of grasping a variation of the inner diameter of the glass substrate to be caused to occur by said chemical strengthening step of each of said plurality of chemical strengthening treatment baths, wherein said grasping step grasps a variation of the inner diameter based on an ion concentration of ions exchanged from strengthening treatments of glass substrates in the chemical strengthening treatment solution in accordance with the number of strengthening treatments of glass substrates treated by the chemical strengthening treatment solution; and a combination determining step of determining the chemical strengthening treatment bath, that performs chemical strengthening on said glass substrate, based on said grasping step, so that the inner diameter of said glass substrate, whose inner diameter is measured, becomes a desired value after said chemical strengthening step; and wherein, in said chemical strengthening step, said glass substrate is chemically strengthened in said determined chemical strengthening treatment bath.