Bearing Design

On a positive note the TMG fan is a very well executed piece of engineering. After reading the literature & schematics on Thermaltake’s website and then seeing this fan in action our suspicions were aroused too exactly what the term “enter bearing” meant. To us if it acts, sounds and feels like a FDB, then it should be considered a FDB variant, and in fact that was what we were going to state. However, just as this review was about to be published Thermaltake was able to not only confirm that it is a proprietary Fluid Dynamic Bearing (FDB) fan but it is made by their OEM partner Everflow.

The main advantages FDB’s have over normal sleeved or ball bearing designs are that they create very little friction and thus create very little noise. This is because the main moving part is separated from the fan housing not by grease or ball bearings but by FLUID and fluid has a tendency to dampen any noises the bearing surfaces make. The easiest way to think of how a FDB system works is to take a normal “sleeved” bearing design and replace the grease with fluid. Some people refer to fluid dynamic bearings as a modified sleeve design. Whatever else you call it, you can call this enter bearing fan quiet.

Here is a diagram showing how the enter bearing works


Here is a Scythe FDB diagram


Similar looking are they not? Of course the Thermaltake is only rated for a "mere" 50,000 hours Mean Time Between Failure (MTBF). Which while certainly acceptable is curiously short, since for example Scythe’s S-Flex line has a MTBF three times longer than this.


Please note:

MTBF numbers are not the same as “expected time before failure”. All MTBF really means is that if you have a MTBF of 50,000 AND you USE 50,000 you can expect 1 to die every hour. It does not mean that ANY will LAST 50,000 hours…a subtle distinction but it is a distinction you shouldn’t overlook.

Unfortunately, manufacturers don’t like to publish the life expectancy of their products. This would give customers a false sense of security, and (where we do live in a litigious society) this “level of expectation” would leave them wide open to a class action suit. After all if they say it “should last X hours” and when a good percentage do not last that long, well lets just say that is the stuff lawyers' dreams are made of.

To get a better “feel” for what the manufacturer thinks is the real length of time a product should last simply look at the length of warranty. The length of warranty has been calculated to be long enough so that customers feel secure in purchasing it BUT still short enough that it will be “out of warranty” when most fail. Taken for what its worth, Thermaltake’s TMG A1 comes with a 6 year warranty.