1Grinding machine bearingsLubrication failure: dry friction "hissing" alarm
Root cause: Insufficient or deteriorated lubricating grease, or incorrect selection (such as using low-temperature grease in high-temperature conditions), resulting in direct contact between the rolling elements and the raceway, producing high-frequency metal friction sound.
Repair Guide:
Cleaning and grease replacement: Clean the interior of the bearing with kerosene and replace it with high-temperature resistant (such as lithium based grease) or high-speed (such as low torque grease) lubricating grease. The filling amount should be controlled at 1/3-1/2 of the bearing cavity.
Sealing inspection: If the sealing ring is aged or damaged, it is necessary to replace the sealing component (such as a fluororubber sealing ring) to prevent grease leakage and contamination from entering.
Case: A dental polishing machine had its bearing temperature rise to 80 ℃ due to the use of ordinary lubricating grease. After replacing it with high-speed lubricating grease, the noise was reduced by 80% and the service life was extended to 1500 hours.
2、 Foreign object intrusion: "clattering" damage of sand particles
Root cause: Metal debris, dust, or impurities in the lubricating grease generated during the grinding process enter the interior of the bearing, forming abrasives between the rolling elements and raceways, resulting in surface indentation and rust.
Repair Guide:
Thoroughly clean: Use an ultrasonic cleaning machine combined with a solvent (such as alcohol) to clean the bearings and remove residual impurities.
Improve sealing: Install dust covers (such as metal mesh covers) or upgrade to labyrinth seals to reduce the probability of foreign objects entering.
Regular maintenance: Clean the debris around the bearing every 50 hours to avoid accumulation.
Case: A certain metal polishing machine had 0.5mm iron chips enter the bearing without installing a dust cover, causing scratches on the raceway surface. After replacing the bearing and installing a dust cover, the failure rate decreased by 90%.
3、 Installation deviation: hidden danger of "clanging" caused by knocking
Root cause: During installation, the fit between the shaft and the bearing hole is too loose (clearance>0.05mm) or too tight (interference fit>0.01mm), or knocking during installation causes deformation of the cage and indentation of the rolling elements.
Repair Guide:
Accuracy control: Use a micrometer to measure the shaft diameter and bearing inner diameter, ensuring that the fit tolerance meets the standard (such as H7/h6).
Hot installation method: For bearings with interference fit, use an induction heater to heat them to 80-100 ℃ before installation, avoiding knocking.
Pre tightening adjustment: By adjusting the bearing end cap or nut, the axial clearance is controlled at 0.01-0.03mm (adjusted according to the speed and load).
Case: A high-speed polishing machine broke its cage due to hitting the bearings during installation. After replacing the bearings and using the hot installation method, the machine ran smoothly without any abnormal noise.
4、 Abnormal clearance: "buzzing" vibration that is too loose or too tight
Root cause:
Excessive clearance: During high-speed rotation, the rolling elements generate centrifugal impact, causing a buzzing sound.
Small clearance: Lubricating grease cannot form an effective oil film, resulting in metal contact friction.
Repair Guide:
Clearance measurement: Use a feeler gauge or dial gauge to measure the axial clearance to ensure compliance with standards (such as micro bearing clearance ≤ 0.005mm).
Adjustment method:
Excessive clearance: Replace bearings with smaller clearance (such as C3 grade) or increase preload force.
Small clearance: Adjust the fitting size by grinding the bearing seat or journal, or choose bearings with larger clearance (such as C4 grade).
Case: A dental polishing machine experienced resonance at a speed of 50000 revolutions per minute due to excessive bearing clearance. After adjusting the clearance to 0.003mm, the noise level decreased from 75dB to 55dB.
5Grinding machine bearingsComponent damage: The "click" sound of the rolling track peeling off is silent
Root cause: Long term overload, poor lubrication or improper installation leading to fatigue peeling of the raceway surface, forming pits or cracks.
Repair Guide:
Damage detection: Observe the surface of the raceway with a magnifying glass or microscope. If the peeling area is greater than 1mm ² or the depth is greater than 0.1mm, the bearing needs to be replaced.
Material upgrade: For high load conditions, high carbon chromium steel (GCr15) or ceramic bearings are selected to improve fatigue resistance.
Operation monitoring: Install vibration sensors to monitor the bearing vibration frequency in real time (such as ISO 10816 standard), and replace it in advance when the vibration value exceeds 50% of the reference value.