What are the criteria for discarding bearing shells?

　　⒈The wear of the bearing shell exceeds 1/3 of its thickness. 　　⒉The wear amount on the pinion tooth surface should not exceed 30% of the tooth thickness, while the wear amount on the gear ring tooth surface should not exceed 25% of the tooth thickness; such teeth can be used with their surfaces reversed. They should be discarded when the wear reaches 1/2 of the original thickness. 　　⒊The twist deformation of the ring gear rim shall not exceed 7.5 mm. 　　⒋The hollow shaft should be replaced when grooves or scars appear on its outer surface, or when there is local wear on its inner circular surface, resulting in deformation or cracks. 　　Maintenance and Repair of Ball Mills Maintenance and repair of ball mills are routine tasks, and the quality of these repairs has a direct impact on the machine’s operational efficiency and service life. The following outlines how to carry out proper maintenance and repair during use: 1. All lubricants should be drained after the mill has been in continuous operation for one month; it should then be thoroughly cleaned and refilled with new lubricant. In the future, oil should be changed every 6 months in conjunction with the regular maintenance. 　　⒉The lubrication status at each lubrication point and the oil level should be checked at least every 4 hours. 　　⒊When the mill is in operation, the temperature rise of the lubricating oil in the main bearings shall not exceed 55°C. 　　⒋When the mill is operating normally, the temperature rise of the drive bearings and the reducer should not exceed 55°C, with a maximum of 60°C. 　　⒌The large and small gears transmit power smoothly, with no abnormal noises. Adjust the gap in a timely manner if necessary. 　　⒍The ball mill operates smoothly, with no severe vibrations. 　　⒎There should be no abnormal fluctuations in the motor current. 　　⒏All connection fasteners are tight, and there is no oil leakage at the joints, nor any leakage of water or minerals. 　　⒐Steel balls should be added promptly as wear occurs. 　　⒑If any abnormality is detected, the grinding should be stopped immediately for maintenance. 　　The maintenance of ball mills is a routine task, and the quality of this maintenance directly affects the operation rate and service life of the ball mills. To detect defects promptly and eliminate potential risks in order to ensure the proper operation of the mill, in addition to routine maintenance, it is necessary to shut down the mill periodically (once a month is recommended) to conduct thorough inspections of key components such as the hollow shaft, main bearings, cylinder, reducer, and gears, while keeping detailed records. Appropriate actions are taken based on the severity of the defects, and maintenance and major repair plans are formulated accordingly. 　　⒒The mill liner should be replaced when it is worn by 70% or has cracks 70 mm long. 　　⒓The gasket bolts should be replaced if they are damaged and cause the gasket to become loose. 　　⒔The main bearings should be replaced when they are severely worn. 　　⒕The grate plates of a grid-type ball mill should be replaced when they are worn to the point where they can no longer be welded and repaired. 　　⒖When the gear surface of the large gear is worn to a certain extent, it can be turned over and used again. 　　⒗The pinion gear should be replaced if it is severely worn. 　　⒘When the feed and discharge screws are worn, they should be welded and repaired promptly; when the wear is such that welding repair is no longer possible, they must be replaced. 　　⒙Loose or damaged anchor bolts should be repaired promptly.

In the case of wear, the criterion for discarding components with non-adjustable clearances is when the top clearance exceeds the maximum value, while for bearing shells with adjustable top clearances, the criterion is when the side clearance exceeds the maximum value. If there is thick skin, peeling, cracks, or melting in a localized area, the item is generally discarded. Personal opinions are for reference only.

So far, no information on the scrapping of sliding bearings has been found in this regard. 1. Generally, shaft bearings can be put back into use only after local melting, cracks, and surface abrasion have been repaired. 2. If the gap is too large, the joint can be ground before being used again; pay attention when adjusting the interference. 3. The interference adjustment can be achieved by increasing or decreasing the thickness of the gasket.