Bearing Design

Because of the nature of fans and how they work, there are two basic bearing designs commonly in use. Ball bearing designs tend to be very robust with significantly longer life spans than their counterparts. However, they are more expensive, owing to their increased mechanical complexity, and tend to be significantly louder in use.

Sleeve bearings are a simpler design, utilizing a porous metal sleeve riding upon a layer of oil. Because of the greater surface area involved in a sleeve bearing design they spread out friction over a wider area and thus tend to be significantly quieter. Modern Hydrodynamic Sleeve Bearing systems take this a step further by pressurizing and sealing the oil within the assembly, utilizing the pressure as an additional stability element to the assembly. Still, from a longevity standpoint, ball bearing designs are still superior.

Noctua, leveraging the work of the Austrian Institute of Heat Transmission and Fan Technology, takes this a step further with their self-stabilising oil-pressure bearing or SSO Bearing, and adds an additional magnet to their motor assembly which helps stabilize centering of the rotor axis, leading to reduced friction and considerably longer lifespan than a more traditional hydrodynamic sleeve bearing design.

Not only does this lead to lower noise in the short term, but it also leads to less noise over the long term as well, not to mention the gains in overall lifespan. Noctua's MTBF (Mean Time Between Failure) ratings are three times longer than the ratings we've seen for most traditional sleeve bearing fans.

Let's move on, and take a peek at the other improvements made by Noctua.