In terms of dimensional changes

Replacement of copper bushings generally needs to be considered when the amount of wear on the inner diameter exceeds the design allowable tolerance. For example, in some precision machinery, if the inner diameter of the copper bushing wears more than 0.1 - 0.2mm (the exact value depends on the precision requirements of the equipment), it will lead to excessive clearance between the mating shaft and the copper bushing. This will not only cause an increase in vibration and noise, but may also reduce the precision of the shaft movement, affecting the normal operation of the equipment.

The wear of the outer diameter of the copper bushing is also critical. If the outer diameter wear makes the copper bushing fit loosely in the mounting seat, for example, the amount of looseness reaches 0.15mm or more, it will lead to inaccurate positioning of the copper bushing, and during the operation of the equipment, the copper bushing may be displaced, which will accelerate the wear and affect the stability of the equipment.

Surface quality

If there are serious scratches, pits or flaking on the surface of the bushing, it needs to be replaced. For example, when the depth of scratches exceeds 0.05mm, these defects will damage the surface finish and flatness of the copper sleeve, making it difficult for the lubricant to effectively adhere and form a uniform oil film. When the equipment is running, the stress concentration at these defects will lead to further wear and tear, and the flaked copper chips may also enter other parts, causing secondary damage.

If the surface of the copper bushing corrosion occurs over a large area, corrosion depth of more than 0.1mm and the area of the surface area of the copper bushing more than 20%, should also be replaced. Because the surface structure of the corroded copper bushing becomes loose and fragile, and its wear resistance and bearing capacity is greatly reduced, unable to ensure the normal operation of the equipment.

Equipment performance affected

When the wear and tear of copper bushings lead to a significant decline in the accuracy of the equipment, such as in CNC machine tools, machining accuracy from the original ±0.01mm down to ±0.1mm or more, it is necessary to replace the copper bushings. Because this decline in precision will make the product quality can not meet the requirements.

If the copper sleeve wear caused by equipment noise and vibration beyond the normal range, for example, the noise level is higher than the normal operation of more than 10dB or vibration amplitude increased by more than 50%, which indicates that the wear of the copper sleeve has been seriously affected by the dynamic performance of the equipment, need to be replaced in time in order to restore the normal operation of the equipment.