FLUID DYNAMIC PRESSURE BEARING, SPINDLE MOTOR AND STORAGE DISK DRIVE DEVICE HAVING THE FLUID DYNAMIC PRESSURE BEARING AND A METHOD OF MANUFACTURING THEREOF

摘要

A fluid dynamic bearing having a shaft and a bearing sleeve 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 is formed by ridges remaining in between multiple dynamic pressure grooves formed by electrochemical machining.