The Serpent Rider wrote on 2024-04-06, 04:03:
TL;DR:
Ball bearing -gets noisy faster, but have easy maintenance.
Sleeve bearing - more quiet, but practically no maintenance.
TL;DR: not true at all.
Ball bearing fans have easy maintenance... ONLY if you have a supply of small bearings to throw at them when the old ones go bad. And let's be honest, how many of you here keep spare bearings for fans? Anyone? 😁 (I know I do, but they are 2nd hand bearings off of Ebay, so not "100% brand new and high quality" as advertised.) Otherwise, if you want to service the old (worn) ball bearing, you have to be very quick to catch it right as it's starting to get noisy. Catch it too late, and it would be too worn out for a "simple" lubrication job. I've actually done that for several fans and a hand rotary tool of mine, and I can't in the least say that it's easy to do. If anything, it's a PITA and takes a good amount of time. To service a noisy BB, you have to remove the thin locking wire and then the metal shields/guards (on BOTH sides!) of the bearing. Then clean with break cleaner and let dry. Finally, stuff the bearing with grease suitable for ball bearings. Some lithium grease types are usually OK for this, though not all. Read the label / datasheet to confirm. Oil of any type is a NO-GO (been there, tried that, didn't get the T-shirt, but did get a randomly-rattling bearing again. 😦 )
Also, some BB fans can also be a PITA to take apart, even if you just want to go for a "simple" bearing replacement job. It really depends on who (manufacturer) made the fan and how it was designed. The locking clip holding the fan rotor shaft to the bearings at the back of the fan can sometimes be quite hard to remove and I've snapped broken a few myself in the years of doing these. I much prefer to see plastic c-washers used here... but many BB fans don't use them.
And lastly in regards to BB fans... no they don't get noisier faster. Actually completely the opposite - they last much longer than sleeve bearing fans. But they are noisier by design. I'm sure some of you remember the noise of (now old) HDDs with ball bearings - these things were never quiet, even from day #1 of use.
As for sleeve bearing fans... yes they are more quiet indeed.
In terms of maintenance, though, they can range from much easier to very hard to service.
Most of the old (retro?) sleeve bearing fans (especially the "no-name" ones) are usually very very easy to service. These typically have just a rubber plug under the label on the back. Peel the label, remove the rubber plug (if there is even one) and you will usually find access to the rotor shaft, held in place to the stator / chassis by means of a plastic locking c-washer. Pry the c-washer apart and off the shaft, and the rotor assembly (top part) of the fan can be pulled off and away for easy cleaning. I do this for ALL sleeve bearing fans that are easy to service like this. It only takes a few more minutes of time, but the results are faaaar better than just put a drop of oil and calling it good. Taking the fan apart allows the shaft and sleeve bearing to be cleaned completely from the old (dried) gunky lubricant and fresh one added. I personally also like to score long grooves into the sleeve bearing material, parallel to the shaft orientation. This allows the bearing to retain more oil and operate very similarly to a "riffle bearing", or whatever they are called. As for lubricant - always use OIL ONLY for sleeve bearing fans. Greases tend to either seize up or push-out over time, leaving the bearing dry again. And synthetic greases like lithium grease often are too "sticky" and can make sleeve sleeve bearing fans turn slower afterwards / perform worse.
That said, going back to how easy (or not) it is to service sleeve bearing fans, modern "sealed" sleeve bearing fans are indeed not made to be taken apart - at least not easily. I cringed a little while reading the above Digikey article, particularly about how the author(s) went about to open some of the sealed fans (melting plastic at the top.) There is actually a less destructive way to open these fans: drill holes on the back to expose the fan shaft, heat the shaft with a soldering iron (that hot, but not so hot to melt solder yet, as you don't want solder to adhere to the steel shaft), and pull the rotor assembly (rotating fan assembly) out. The reason for the heat with the soldering iron is that these "sealed" sleeve bearing fans usually have their locking c-washer at the top of the shaft, near the rotor part. So it's impossible to get to. By heating the metal shaft, this softens the plastic locking c-washer and allows the rotor assembly to be pulled apart without damage. Once that is done, the rest of the procedure is the same as for cleaning and lubricating a regular sleeve bearing fan mentioned above. Only difference is when putting back the fan together - for a sealed sleeve bearing fan, you would want to save some of the plastic that was drilled out from the back and re-glue it again. Otherwise many sealed sleeve bearing fans tend to get "sunken" rotor assemblies, since there is nothing to hold the shaft from going further in towards the back of the fan. Probably easier to demonstrate how I do this with pictures (should really write a "HOW-TO" article on this)... but it is not too hard to do.
The Serpent Rider wrote on 2024-04-06, 04:03:No modern high-end hydrodynamic or magnetic bearing spotted.
These are just variants of the sleeve and ball bearing designs, with a few improvements (and lots of marketing hype/bullshit) on top.
Ozzuneoj wrote on 2024-04-06, 17:43:What I found interesting was the pictures which help a lot in identifying the different types of fans and which ones (hint: most fans) cannot be opened up without destroying the fan.
Not anymore, that is.
Most old fans were fairly serviceable, even the cheap "garbage" / no-name ones. Modern crap is made to be assembled as cheaply as possible and no one cares for it to be repairable... so companies don't bother with putting in convenient rubber plugs or other means to get access to the fan bearings. Most fans nowadays are press-fitted by a machine and that's that.
