The Truth About Fluid Dynamic Bearing (FDB) Fans

Alternative Design 1 (Rifle Bearing)

The “alternative design 1” we identified is shown in Figure 3, and is used in fluid dynamic bearing fans from Aerocool, Arctic, BitFenix, and SilenX. On this design, the inside of the bearing is smooth, and there are several grooves alongside the exterior of the bearing, where lubricant flows from one end of the bearing to the other. The number of grooves vary: we saw twelve on the Aerocool Shark 120mm Black Edition and Arctic AFACO-120P0-GBA01, ten on the Arctic AFACO-12PP0-GBA0, and nine on the BitFenix BFF-LPRO-12025R-RP and SilenX EFX-12-15. From all “alternative” fluid dynamic bearing designs, this is the most high-end. The confusion here is that this kind of bearing is also called “rifle bearing” by several companies. Companies that sell fans based on Matsushita’s design think that fans based on this alternative design should all be called “rifle bearing,” so users would be able to compare apples to apples.

Figure 3: Alternative design 1 – rifle bearing (Aerocool Shark 120mm Black Edition)