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How to determine if deep groove ball bearings need to be replaced?

Release time:

2025-06-20

To determine whether a deep groove ball bearing needs to be replaced, a comprehensive inspection from multiple dimensions such as operating conditions, performance parameters, and appearance details is required. The following are systematic judgment methods and practical operation guidelines to help quickly identify the risk of bearing failure: 1. Visual and tactile preliminary inspection: a. Appearance damage detection: mechanical damage: after disassembly, observe the surfaces of the rings, raceways, and balls. If any of the following conditions occur, the bearing needs to be replaced: cracks, notches, or peeling (such as when the metal on the raceway surface flakes off, as shown in Figure 1); obvious scratches or indentations (depth > 0.1mm will increase friction); cage deformation or fracture (such as when a resin cage breaks or a metal cage rivet loosens). Corrosion and rust: rust spots or blackening appear on the surface of the rings (common in humid environments), even slight rust will reduce the bearing's stiffness; lubricating grease drying, caking, or mixed with metal debris (in the form of brown or gray paste, indicating severe internal wear). b. Clearance abnormality detection: manual shaking test: fix the inner ring of the bearing, shake the outer ring axially / radially. If there is a significant gap (refer to Table 1 for normal clearance), or the rotation is stuck or there is abnormal noise, it indicates that the raceway is worn or the steel balls are out of round. Clearance measuring tools: use a feeler gauge or a micrometer to measure the radial clearance. If the measured value exceeds 1.5 times the standard value (for example, the standard radial clearance of a 6205 bearing is 12-27μm, and if it exceeds 40μm, it needs to be replaced immediately). 2. Operating status dynamic monitoring: a. Temperature abnormality warning: temperature measurement tool: use an infrared thermometer to detect the temperature of the bearing housing. If it exceeds the following thresholds, be vigilant: in normal temperature environments (≤30℃), the bearing temperature is >70℃ (temperature rise >40℃); in high-temperature environments (such as kiln equipment), the temperature exceeds the material's tolerance limit (for ordinary bearing steel, >120℃ will anneal and soften). Temperature sudden rise causes: failure of lubricating grease, installation too tight, or abnormal load, immediate shutdown for inspection is required. b. Vibration and noise analysis: stethoscope / vibration instrument detection: abnormal noise types: sharp screeching: insufficient lubrication or oil film rupture during high-speed operation (such as a 608 bearing with insufficient lubrication); periodic impact sounds: steel ball wear or raceway peeling (similar to "clicking" sound); dull abnormal noise: eccentric installation or uneven load causing local overload. Vibration value standard: measure the acceleration using a vibration meter (unit: g), when the vibration value exceeds 2 times the "good" level in the ISO 10816 standard (such as motor bearings >2.8g), it indicates a bearing failure risk. c. Performance parameter quantitative assessment: 1. Calculating the rated life: compare according to ISO 281 standard, the basic rated life (L10h) calculation formula is: \(L10h = \left( \frac{C}{P} \right)^3 \times \frac{10^6}{60n}\) where C is the rated dynamic load, P is the actual load, and n is the rotational speed (r/min). If the operating time of the equipment exceeds 80% of the calculated life (such as calculating L10h = 20000 hours, after 16000 hours of operation, even without obvious abnormalities, it is recommended to perform preventive replacement). 2. Precision attenuation test: rotational accuracy detection: install the bearing on a core shaft and use a micrometer to measure the radial runout of the outer ring: for precision equipment (such as machine tool spindles): the runout should be >0.01mm for replacement; for ordinary machinery: the runout should be >0.05mm when it affects machining accuracy.

How to determine if deep groove ball bearings need to be replaced?

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