Pump Case Study
Invalid Case
20190906 Application Case: A customer in the motor industry reported that their end‑user observed an abnormal noise immediately upon starting the motor. The motor is equipped with two sets of 6203‑2RS bearings.
According to testing by our company’s technical personnel, all dimensional measurements are within specifications; only the noise level exceeds the standard. The detailed analysis is as follows:
1: The customer brought back the bearing from the site, as shown in the figure: there are no obvious signs of installation or wear on its exterior; when rotating the bearing, a noticeable binding is felt, and the elevated noise level further suggests that the raceway has been damaged.
2: After prying open the bearing cover, the grease near the inner and outer rings has discolored (turned black), but it has not completely lost its lubricating performance.
3: The inner raceway exhibits overall wear. Wear marks are evenly spaced along the raceway, with a higher concentration of electrical erosion pits at the centers of these marks; extending outward from these pits is fretting wear.
4: The outer raceway exhibits overall yellowing. Within the raceway, wear marks are evenly spaced; at the centers of these marks, numerous electrical erosion pits are observed, and micro‑motion wear propagates outward from these pits.
5: The steel ball’s surface has turned uniformly yellow. There are severe surface scratches, and obvious pitting caused by electrical erosion is present.
Draw a conclusion
Based on the analysis of the failure symptoms, it is determined that equipment leakage current passes through the bearing, creating a potential difference between the outer and inner rings. This leads to breakdown of the lubricant film and subsequent electrical erosion. Electrical erosion, along with contaminants and raceway defects, results in fretting wear during radial micro‑motion operation.
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