Fluid Dynamic Pressure Bearing, Spindle Motor and Storage Disk Drive Bearing and a Method of Manufacturing Thereof

摘要

A fluid dynamic bearing having a shaft ( 12 ) and a bearing sleeve ( 11 ) rotatably supported relative to each other. At least one of the shaft and the bearing sleeve is made of steel or stainless steel made of by weight C: 0.6~1.20%; Si: 1.0 or less; Mn: 1.0% or less; Cr: 10.5~18.0%; Mo: 1.0% or less; S.: 0.03% or less; and Fe. The dynamic pressure bearing surface ( 20 ) is formed by ridges ( 22 ) remaining in between multiple dynamic pressure grooves ( 21 ) formed by electrochemical machining.