Deep groove ball bearing consists of an outer ring, an inner ring, a group of steel balls and a group of cages. There are two types of deep groove ball bearings: single row and double row. Deep groove ball structure is also divided into seal and open structure. The open type means that the bearing has no sealing structure. The sealed deep groove ball is divided into dust-proof seal and oil-proof seal. The dust-proof seal cover is made of steel plate, which only serves as a simple way to prevent dust from entering the bearing raceway. The oil-proof type is a contact oil seal, which can effectively prevent grease overflow in the bearing.