Demonstration and test of 35 fans

Details of our test participants

As you can read in the introduction, one of the most important factors for fans is the bearing. For a long time, only sliding - or, if you prefer a glider - bearing bearings existed, and then ball-bearing versions appeared. We’ve adored these for years, because how much better it sounds to have a ball-bearing vent. Then, as time went on, sliding bearing pieces began to leak back onto the shelves, in addition to not only the cheap but also the more expensive segment. Then, to make things even more complicated, liquid-bearing fans also appeared. Here, then, the average buyer no longer knows what he is up against, since what kind of thing is that there is fluid in the engine instead of the bearing. Stupidity. Such cannot exist, and as we read on, it will turn out that it does not even exist.

Ball bearing

Let's start with the ball bearing fans! I think everyone has some idea what such a bearing looks like. In general, the bearing consists of three main parts. These rings, the inner of which is pressed onto the shaft, the outer, which is in contact with the bearing housing, and the balls, which, with a little exaggeration, allow frictionless running, rotation between the two rings, such as the motor shaft and the bearing housing.

Technology also has advantages and disadvantages. The advantages are that in normal cases their operation is relatively maintenance-free, due to the low friction there is a small chance of wear and tear, and they have a long service life. Their disadvantage is that the shaft must be mounted in at least two places to prevent it from swaying and to be noisy. The noise is higher than that of a plain bearing because there is simply no technology that can produce completely regular balls and rings at the right manufacturing cost. Because of this irregularities, the ball bearing will then “hit” a bit and noise will be generated. In my opinion, the worse thing about the fans is that they can't put many ball bearings in the motors due to their size, which again leads to the fact that the run will not be smooth.

Plain or plain bearing

However, there is a solution where no balls are needed, and that is the plain bearing. Like any solution, it has its pros and cons, but before we get into that, let’s look at what components make up a bearing.

Here we also have to fix ourselves right away, since in the case of a fan we can only talk about one main part, and that is the bearing bush. This is made of bronze in most cases, and especially in the case of the aerators we discuss. The bronze bushing is simply pressed into the bearing housing and the shaft rotates in the middle of the bushing. Here comes the big question of what without lubrication helps the rotation, why not produce enough heat to get the whole structure in. For the sake of accuracy, it is worth noting that an axle pin will be needed outside the bushing, in the case of fans, rather a support disk, which prevents the motor shaft from moving vertically.

Of course, the fact that there’s no lubrication isn’t true, it’s just not conspicuous. Bronze, as an alloy, contains a variety of other metals, some that are softer and provide better lubrication than copper. The most common types are aluminum, tin and lead bronze bushings. Lead bronze is also the best solution of these, as it has the best lubrication of the three, it has adequate wear resistance compared to it, so it is also less prone to sticking. Bronze bushings are also cooked in oil for better lubrication, further improving their gliding properties.

As we have written, the plain bearing also has advantages and disadvantages. Their advantages are simple structure, cheap production, almost complete lack of tendency to sway, and quiet operation. The disadvantages are the higher friction, the resulting faster wear, and the fact that they are more sensitive to lubrication failure.

Fluid bearing

In our case, we are discussing a solution called S-FDB (Fluid Dynamic Bearing), a trademark of Sony. The bearing is actually nothing more than a plain bearing. The main difference compared to the conventional solution is that in this case a high-pressure oil film is formed between the shaft and the bushing, which ensures lubrication. At the “bottom” of the engine, i.e. on the side of the shaft opposite the blades, we find an oil bath, in which the end of the shaft “stands”. Although no precise description of the technology has been found, it is likely that the narrowing gap between the shaft and the bushing and the rotation will result in the formation of the high-pressure oil film layer that ensures glide. A seal is found at the top of the bushing to prevent oil from leaking towards the blade.

Another interesting fact is that in the motor we find additional magnets under the blades, the role of which is to reduce the oscillation as much as possible, so that the rotor and the blade rotate more evenly, thus reducing wear and noise.

Thanks to Sony's technology, conventional plain bearings have much less noise and a much longer service life, three times the life of traditional solutions. Of course, we have no practical evidence for this yet, but in a few years it will be revealed whether the factory data is true.

Now that we have reached the end of the descriptions of the bearings, the test subjects may be introduced!