**Introduction to the Main Bearing of a Cement Mill**
Home > Bearing Knowledge > Introduction to the Main Bearing of a Cement Mill
Source: China Bearing Network | Time: 2014-06-28
The traditional main bearing in cement mills typically uses wool felt rings for sealing, which are prone to wear and offer unreliable protection. According to theoretical analysis, dust particles can enter the main bearing through the gap between the worn wool felt ring and the hollow shaft. These particles are a major cause of abrasive wear and blockage in the spherical SKF bearing bush. Therefore, improving the sealing system is essential.
To address this issue, the author introduced a radial labyrinth sealing method. This approach involves using two steel sealing rings—one male and one female—designed to fit into a radial annular labyrinth groove according to the principles of labyrinth sealing. The male ring is fixed on the main bearing cover, while the female ring is attached to the hollow shaft of the mill. A layer of grease is applied in the labyrinth before installation to reduce friction and enhance sealing performance. This design prevents dust and impurities from entering the main bearing, significantly improving its reliability.
In addition, improper gear meshing between the balance shaft gear and its corresponding axis can lead to mechanical stress and potential cracking of the balance shaft. This issue highlights the importance of maintaining proper alignment and minimizing vibration during operation.
A large number of cement mill failures are attributed to poor construction or maintenance of the main bearing. Therefore, it is crucial to improve the assembly techniques of the bearing bush, enhance the sealing system, and implement appropriate lubrication methods to ensure smooth operation. As the cement industry moves toward larger-scale and automated production, preventive maintenance becomes even more important. Companies must develop detailed pre-repair plans to avoid unexpected downtime.
During operation, friction and heat are inevitable between the hollow shaft journal and the main bearing’s spherical tile. This leads to energy loss due to friction power consumption. Additionally, issues such as loose bearings, misalignment, and excessive axial clearance can cause abnormal wear and even damage to the bearing housing.
To reduce friction and wear, maintain temperature control, and extend the service life of the bearing, ensuring high-quality lubrication is critical. Some cement plants have experienced severe problems, such as burnt bearing tiles or worn hollow shaft journals, due to poor lubrication or contamination. Repairing these issues can take several hours or even days, causing significant production delays and economic losses.
When a new mill is first started, an oil film may not yet form on the bearing surface. Therefore, it is recommended to apply lubricating oil to the surfaces of the mill's two shafts before testing. This helps prevent the bearing from being damaged by dry friction. After running-in, the lubricant should be replaced with clean oil to remove any small babbitt particles that may have formed during the initial operation.
During engine disassembly and repair, improper installation of components like the balance shaft or timing gears can lead to imbalance and increased vibration. This can result in damage to the balance shaft over time. Proper installation and alignment are therefore vital for long-term performance.
**Related Bearing Knowledge**
- The layout of the bearing, bearing seat product, and device orientation
- Rust prevention methods for bearings
- Standard conditions for sealed storage of SKF bearings
- Correct application of spindle bearings
This article is sourced from China Bearing Network. For more information, please visit [http://www.chinabearing.net](http://www.chinabearing.net).
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Model No.
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CG-25
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Max. flow rate
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200kg/min
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Nominal diameter
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25mm( 1 inch)
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LNG accuracy grade
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±0.2%
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Zero stability
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2 years
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1set/carton
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