| 摘要 |
PURPOSE:To polish the surface of a titanium made magnetic disk substrate material in high accuracy of plate thickness by setting its tolerance of the substrate material to 0.9 times or less the degree of flatness in the surface of a surface plate. CONSTITUTION:Plate thickness tolerance X (mum/m) of a titanium-made magnetic disk substrate material is set to 0.9 times or less the flatness degree Y (mum/m) of a surface plate surface. Thus during polishing, a total surface of the titanium- made magnetic disk substrate material is uniformly brought into contact with a surface plate, and generation of parts with large and small polishing amount in a substrate surface can be prevented. Consequently, the substrate surface can be uniformly polished by abrasive grains, as a result, excellent accuracy of plate thickness can be attained. |
