Abstract: An integral type thrust bearing is proposed which can be manufactured with fewer heat treatment steps. The retainer and the inner and outer rollers not hardened are assembled together with rollers into a bearing and thereafter the assembled bearing is carburized, hardened and tempered. This eliminates the need for individual heat treatment of the retainer and the inner and outer rings and decreases heat treatment steps for the production of thrust bearings.

Abstract: An integral type thrust bearing is proposed which can be manufactured with fewer heat treatment steps. The retainer and the inner and outer rollers not hardened are assembled together with rollers into a bearing and thereafter the assembled bearing is carburized, hardened and tempered. This eliminates the need of individual heat treatment of the retainer and the inner and outer rings and decreases heat treatment steps for the production of thrust bearings.

Abstract: A polishing composition for a memory hard disc, which comprises the following components (a) to (d):(a) water,(b) at least one compound selected from the group consisting of a polystyrenesulfonic acid, and its salts,(c) a compound selected from the group consisting of an inorganic acid and an organic acid, and their salts, other than component (b), and(d) at least one abrasive selected from the group consisting of aluminum oxide, silicon dioxide, cerium oxide, zirconium oxide, titanium oxide, silicon nitride and manganese dioxide.

Abstract: The needle roller bearing A comprises a cage 3 having a plurality of long window-shaped pockets 3a formed at an appointed interval on its circumference, and a plurality of needle rollers 4 rollably accommodated and retained in the pockets 3a of the cage 3. The connection radius R (radius of curvature) between the inner diameter side portion of the pocket wall surface 3a1 and the inside surface 3b1 of the annular portion 3b, and the connection radius R (radius of curvature) between the inner diameter side portion of the pocket wall surface 3a2 and the inside surface 3b1 of the annular portion 3b of the cage 3 are set to a value having a relationship of 0.2<R/Dr.ltoreq.0.5, preferably 0.3.ltoreq.R/Dr.ltoreq.0.5 with respect to the diameter Dr of the needle roller 4.