Maintenance and care for deep groove ball bearings: maximum operating speed

Maintenance and care for deep groove ball bearings: maximum operating speed

When deep-groove ball bearings operate under a load condition of 0.1C, the increased contact stress between the rolling elements and the raceway surfaces causes the bearing operating temperature to rise, leading to a relative deterioration in the performance of the lubricant; consequently, the limiting speed of the deep-groove ball bearing will be reduced accordingly.

For the range where C/=10, as the reduction in limiting speed is negligible, this may be disregarded; that is, f1 may be taken as 1.

For radial bearings subjected to combined loads, the number of rolling elements bearing the load increases, leading to greater frictional resistance, higher heat generation and poorer lubrication and cooling conditions. Furthermore, the forces acting on the cage also increase. Consequently, the limiting speed of deep-groove ball bearings must be adjusted by multiplying it by a reduction factor f₂ based on the bearing type and the magnitude of the load angle.

If the limiting speed of the selected bearing does not meet the operational requirements, certain technical improvements may be implemented to increase it and achieve a satisfactory level of performance. These include: increasing the bearing tolerance class; appropriately increasing the clearance; using special materials and improving the cage design; changing the lubrication method, such as adopting oil-air, oil mist or jet lubrication; and improving cooling conditions.

I. Inspection Methods for Bearing Lubrication and Maintenance

During operation, the lubrication lines must be kept clear, and seals should be inspected regularly to ensure they are intact; damaged seals must be replaced promptly. Operational conditions must also be monitored, focusing on three aspects: noise, lubricant condition and temperature. During normal operation, a steady humming sound should be audible; any abnormalities must be addressed promptly. A normal lubricant is clear and clean; if it has become contaminated, it will contain wear particles or pollutants. An increase in temperature will result in abnormal operation.

II. Specific Steps for Bearing Lubrication Maintenance

1. The Importance of Lubrication

Great importance must be attached to bearing lubrication technology. Lubrication utilises an oil film to separate the relative moving rolling surfaces, preventing failure due to excessive wear caused by rough point contact. It also ensures that stable performance and rotational precision are maintained throughout the specified service life.

2. Classification of Lubrication

Lubrication is divided into grease lubrication and oil lubrication. The advantages of grease lubrication are that the lubrication system is simple, the grease does not leak easily, and it offers a certain degree of resistance to the ingress of water, air and other contaminants; therefore, grease lubrication is widely used under normal circumstances. Oil lubrication is used under conditions such as heavy loads, high speeds and high temperatures. 3. Use of Grease

The amount of grease applied must be appropriate. It is best to fill one-third to one-half of the space within the bearing and deep-groove ball bearing housings. If too much grease is applied, agitation and heat generation may cause the grease to deteriorate or oxidise. At high speeds, the bearing should be filled to one-third capacity or less. At very low speeds, the housing may be filled to capacity to prevent external foreign matter from entering the bearing.

4. Storage of Bearings

The environmental conditions for storage and preservation are relatively stringent, particularly with regard to temperature and humidity. All bearings must be coated with anti-rust oil prior to leaving the factory; the room temperature should be maintained between 0 and 25 °C, and the relative humidity should be kept between 45% and 60%.