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How to Choose Cooling Fan
- May 18, 2018 -

The fan plays a central role in actively cooling the CPU's air-cooled heat sink. The performance of the fan itself is not good, and the manufacturing process is not precise, which can lead to local overheating of the heat sink, and constantly burn the material plastic of the fan itself, causing a fan to deform, a vicious cycle of falling speed, and in more serious cases, a fan stall occurs. A short circuit in the motor circuit burns the CPU and even causes a fire accident.

There are many factors that determine the heat dissipation performance of a fan. Recently, the cause of widespread concern is the bearing transmission mode of the fan. The cooling fan currently used in the market is mainly using two types of bearing transmission methods:

Self-lubricating bearings: also known as oil bearing. Its working principle is mainly due to the rotating rod in the bearing under the action of the lubricant. When rotating in the shaft bed, due to the capillary action, only a slight contact with the surrounding, so that the friction is reduced to the minimum, ensuring the stability during work. The problem with self-lubricating bearings is that they are highly dependent on lubricants. When the amount of lubricant is insufficient or the viscous properties are poor, the bearings are prone to ageing, causing the fan speed to drop, or making abnormal noise, so the overall life is not long.

Ball bearing: This is the most widely used bearing transmission method in the CPU cooling fan. Its structure is also not complicated. In the middle of two hard metal rings, there is a series of metal balls fixed by relative positions in the shaft cage. Lubricant is added between the shaft cage and metal ball. In this way, when the bearing rotates, the contact surface between the ball and the rotating track is extremely small. As long as there is a small amount of lubricating material, the entire bearing structure can maintain a long life and maintain good performance.

The problem of the structure of the ball bearing is mainly because the working noise is slightly larger, and the user cannot add lubricant to the bearing himself. Therefore, it is very important to select a reliable manufacturer when selecting the ball fan. In contrast, although self-lubricating bearing maintenance is relatively simple, but if you want to achieve the same rotation performance with ball bearings, you need to design a more complex internal structure, which virtually increase the cost of fan manufacturing, not suitable for large-scale produce.

In addition, if there is a bearing problem, ball bearings can often have more obvious early warning, such as speed drop, noise, etc.; and self-run bearing failure is often difficult to predict. Therefore, everyone who sees the most in the market is a fan with a ball-bearing drive.

However, more and more manufacturers are now using two types of bearing hybrid design to accommodate the advantages of these two forms, which may be a development direction of fan design in the future.