Table of Contents

ABSTRACT

Herringbone-grooved journal bearings are preferred in high speed applications such as in cryogenic turbo-expander rotors or in HDD spindle of computers. This paper deals with the manufacturing of shallow (20 to 30 micron deep) herringbone pattern grooves on a rotor surface by chemical milling. A new method of masking using laminated object manufacturing (LOM) paper is presented. The LOM paper has thermally activated adhesive coating on one side. Compared to the conventional method of masking, the proposed method has several advantages. A chemical milling facility is developed for etching stainless steel rotors. Using a volumetric mixture of 58% HNO3 , 6% HCL and 36% water as the etchant solution, an etching rate of 2 micron/min is achieved. Surface finish, groove depth and uniformity of the etched grooves are examined by using a surface roughness tester.

Keywords: Grooved bearing, paper-masking, chemical etching