Patent ID: 7988810

Claim:
A method of manufacturing a sleeve unit for use in a fluid dynamic assembly that includes a sleeve and a sleeve housing, the method comprising the steps of: a) arranging the sleeve to have a hollow substantially cylindrical shape centered on a center axis including an upper bearing surface on an upper axial side of the sleeve, and arranging the sleeve housing to have a hollow substantially cylindrical shape including an inner diameter substantially the same as or greater than an outer diameter of the sleeve, such that the sleeve and the sleeve housing are axially separated from each other, the sleeve housing including a flange portion and a lower portion arranged axially below the flange portion, a lower surface of the flange portion extending approximately radially toward the lower portion; b) moving the sleeve toward the sleeve housing along the center axis and inserting the sleeve into the sleeve housing to set a distance between the upper bearing surface and the lower surface along the center axis to be equal to, or approximately equal to, a predetermined distance; and c) fixing the sleeve to the sleeve housing; wherein the sleeve includes an array of dynamic pressure generating grooves; a radially outer diameter of the flange portion is greater than a radially outer diameter of the lower portion; and in the step b): the upper bearing surface of the sleeve is brought into contact with a lower surface of a sleeve holding portion and is biased toward the sleeve holding portion; the lower surface of the flange portion of the sleeve housing is brought into contact with an upper surface of a sleeve housing holding portion and is biased toward the sleeve housing holding portion; and a distance along the center axis between the lower surface of the sleeve holding portion and the upper surface of the sleeve housing holding portion is set to the predetermined distance.