Due to the particularity of its products, the industry standard of the DC cooling fan of the car radiator fan is: For the cooling fan with an outer frame, according to the size of the cooling fan, the single floor is 30-100CM, six sides, free fall in 1CM thick On the wooden board, the cooling fan is partially damaged, but the cooling fan can run normally, and the electrical performance is qualified. It seems that the landing standard is not high, the main reason is that the internal structure of the cooling fan is closely matched, such as the bearing and the middle tube, the stator and the middle tube, and the motor shell and fan blade are all a close-fitting structure. It is not an integrally formed over-standard height floor. When the floor is impacted, the structure size changes, which will cause the cooling fan to make abnormal noises, and it will not be stuck. The over-standard height falls to the floor. For commonly used frame leaves, the plastic material is PBT material. Tubes, ribs, and fan blades are easily broken, which may cause the cooling fan to fail to operate. For the double-ball type fan, the change to PC material can withstand the higher standard landing requirements.