Due to the importance of the roller lubrication system to the bearing of the vertical mill, a simple method can be used to quickly diagnose whether the roller bearing is faulty in normal production:One is to observe the oil condition in the grinding roll on site, or to determine whether the bearing of the grinding roll is damaged by detecting the content of metal particles in the oil sample. If the content of metal particles in the oil sample is high, the bearing has been seriously damaged.The second is to observe the oil return temperature of the ultrafine vertical mill. If the oil return temperature of a certain ultrafine vertical mill rises and the return oil temperature of other ultrafine vertical mills is normal, it indicates that the bearing of the ultrafine vertical mill is damaged.