First of all, we must know that many factors determine the level of fan noise, including speed, fan blade size, fan dynamic balance, and the user’s noise environment. However, the most important factor is the bearing of the fan itself.
The major function of fan bearing is to make fan blades operate fluently. The purpose of fan bearing is to reduce rotational friction and support axial loads.

Fans bearing can be found in many designs, particularly in those that operate in normal temperatures and on static equipment. Applications, such as computer and office equipment, HVAC appliances, and industrial cabinets make extensive use of sleeve-bearing fan designs.

Bearing design for fans may be designed in a variety of ways depending upon the size, operating conditions, etc. and a wide range of oilless bearings would be required to cover every type of application.
Particulars of suitable bearing seating tolerances are given in the application notes but it should be remembered that the selection of tolerances relates, in these instances, to the sizes of bearings applied.
Consequently, for similar applications using bearings of other sizes. it may be necessary to select different tolerances for the shaft seatings. Recommendations regarding tolerance selection are to be found in the VIIPLUS General Catalogue. However, it is advisable to consult VIIPLUS about tolerances for fans bearing for special operating conditions.

Compared with roller bearings, VIIPLUS fan bearings have such advantages: simple construction, low failure rate, easy maintenance, reliable operation, low noise, and low cost. On the contrary, if you use ball bearings, the only benefit is that the initial operation is slightly power-saving, but there are many disadvantages.

The first is the high cost. The installation of roller bearings requires precision machining of the mounting area, and the cost of the bearings themselves is high.

The second is poor reliability. Roller bearings do not allow dust to enter the gap, otherwise, it will seriously affect the operating life.

The third is poor maintainability. Once the ball bearing is damaged, the replacement needs special tools, the installation process requirements are also high, time-consuming, and laborious.

The fourth is the noise. Ball-bearing use of time to generate clearance after the noise will greatly increase, unbearable.

In general, the fan bearing uses plain bearings, the advantages are far greater than the use of ball bearings. A good fan, using powder metallurgy technology sliding bearings has been very perfect. As for the low life of some fans, it has a lot to do with the lack of timely maintenance, no matter what bearings are used, such high-speed rotation of the product, is in need of regular maintenance.

1. Surface dust: The dust on the surface of the rotating shaft and the dust on the inner hole wall of the fan bearing will affect the noise. Before assembly, the surface of the shaft should be wiped clean with a lint-free cloth.

2. Surface scratches and bruises: The shaft and the fan bearing are both precisely matched. The bruise on the shaft surface or the scratch on the inner wall of the bearing will cause scratching friction noise, and at the same time destroy the stability of the fan and affect the life of the motor. Care should be taken to avoid bumps during the rotation of the shaft and the processing and handling of the semi-finished rotor.

3. The adjustment is not smooth: the structure of the fan motor bearing is required to tap the periphery of the end cover with a hammer to make it smooth, concentric, and smoothly transfer after assembly. If the rotor is not concentric, the rotor will be stuck. Due to the weight of the rotor, the center of gravity will deviate to one side, resulting in large periodic friction noise. conform to the judgment standard.