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Measures to Reduce Wear of Ball Mill Gears
Mar 26, 2018

According to our company's ball mill operating conditions and maintenance experience over the years, every two major repair cycles need to replace a pair of gear wheel and pinion.

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1.  Ball mill steering requirements

The ball mill's pinion layout angles and steering are as following pictures shown.

The layout angle of the pinion gear is usually about 20°, which is equivalent to the gear pressure angle. At this time, the positive pressure P1 of the pinion gear is vertically upward, so that the transmission bearing is subjected to vertical downward pressure and is beneficial to the connection bolt and foot of the pinion bearing, work well and run smoothly. Since p1 is vertically upward, the force on the main bearing of the drive end of the mill is reduced, so that the wear of the main bearing bushing is reduced. (In addition, reducing the horizontal area of the mill can make the base of the transmission bearing and the main bearing of the mill on the same plane, so it is easy to change the pinion.) If the ball mill turns in the opposite direction to the illustration, the connection bolt will loosen and Broken.



2.  Improvement of gear lubrication

The lubricant of the ball mill gear mostly uses grease and adds the grease at the gear disengagement point. The lubrication method is also often manual addition or automatic injection lubrication device.


No matter how the grease added is rotated with the gear, most of the grease is thrown toward the gear cover under the effect of centrifugal force and drops to the gear in the vibration of the gear cover, is thrown to the gear cover, and finally falls to the bottom of the gear cover. The lubrication condition of the gear is poor, and dry friction or boundary friction occurs at the partial meshing point of the gear surface.


Ball mills are mostly open drives. The seal of the gear cover is poor. The slurry often contains impurities such as pulp and powder particles. This can cause abrasive wear, resulting in even worse gear lubrication conditions, aggravating gear wear and shortening the operating life of the gears, and a serious waste of grease.


The ball mill gear adopts automatic oil injection lubrication device, and the grease is sprayed into the gear's intermeshing position. This improvement simply moves the automatic nozzle to the point where the gear meshes before, fixes it on the gear cover and makes the tubing connection. In order to prevent the vibration of the gear cover from affecting the oil line, a hose is preferably used for the nozzle and the oil supply system. The grease is sprayed into the gear before entering into the mesh and is promptly brought into contact with the teeth to form a lubricating film on the gear surface, which improves the lubrication condition of the gear and prevents grease from splashing. This effectively extends the operating life of the gear and saves grease.


However, long-term injection of grease cannot be recovered, accumulate in the gear cover and need regularly clean the gear cover. This method is mostly used in some heavy-duty ball mills, such as large-scale slurry mills, cement mills, etc.


Another method is to use lubricating oil instead of grease, which must be sprayed continuously before the gear enters into engagement to form a lubricating film. Lubricating oil flows in the gear cover and enters the oil station and is recycled after being filtered. Lubricating oil instead of grease has a high requirement for the sealing performance of the gear cover. This method is mostly used in some ball mills with lower loads, such as coal grinding mill.

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3.  Summary

Under the premise of satisfying the requirements of the ball mill's steering, it is of great significance to extend the running life of the ball mill gear part by improving the injection point and injection method of the gear part lubricant and reduce the running cost of the ball mill.