Abstract: The circumferential edges of glass or ceramic disks used in disk drive data storage devices are preferably finished by ductile grinding to produce an essentially fracture-free surface, which is not chemically strengthened. Preferably, the material is glass, and both the inner and outer edges of the disk are finished. Edge finishing is preferably achieved in a two-stage process, involving a coarse grind and a ductile grind, using air bearing spindles rotated at high speed for grinding wheels and workpiece. Preferably, the grinding wheels are shaped to provide a radius at the juncture of the circumferential edges and flat disk surfaces.

Abstract: The circumferential edges of glass or ceramic disks used in disk drive data storage devices are preferably finished by ductile grinding to produce an essentially fracture-free surface, which is not chemically strengthened. Preferably, the material is glass, and both the inner and outer edges of the disk are finished. Edge finishing is preferably achieved in a two-stage process, involving a coarse grind and a ductile grind, using air bearing spindles rotated at high speed for grinding wheels and workpiece. Preferably, the grinding wheels are shaped to provide a radius at the juncture of the circumferential edges and flat disk surfaces.

Abstract: Pressure is measured inside of a high pressure vehicle. A substance is compressed at a first pressure to create a preform having a first density. The preform is placed inside of a high pressure vessel and subjected to a second pressure, greater than the first pressure. The preform therefore changes in density to a second density, greater than the first density, whereby the second pressure can be determined. The method may also be used in determining the pressure inside of a food product during food processing and a high pressure vessel.

Abstract: The circumferential edges of glass or ceramic disks used in disk drive data storage devices are preferably finished by ductile grinding to produce an essentially fracture-free surface, which is not chemically strengthened. Preferably, the material is glass, and both the inner and outer edges of the disk are finished. Edge finishing is preferably achieved in a two-stage process, involving a coarse grind and a ductile grind, using air bearing spindles rotated at high speed for grinding wheels and workpiece. Preferably, the grinding wheels are shaped to provide a radius at the juncture of the circumferential edges and flat disk surfaces.