Precautions for replacing grease
author: Leila
2024-07-26
Grease is commonly known as butter. Lubricating with grease is an effective measure to reduce friction and improve the anti-wear performance of various moving parts of machinery. So what should we pay attention to during the replacement of grease?
1. The amount of grease added should be appropriate
According to statistics, excessive grease is a major cause of bearing lubrication failure. Before each filling, do not add more blindly, but make a scientific calculation based on the requirements and conditions of the equipment, such as speed, size, type, etc., so as to know the amount of oil to be added. If an automatic lubrication system is used, it should be noted that the amount of each filling and the frequency of refueling should be calculated and adjusted to avoid excessive refueling. If the amount of grease added is too large, the friction torque will increase, the temperature will rise, and lubrication failure will occur; if the amount of grease added is too small, reliable lubrication cannot be obtained and dry friction will occur. Generally speaking, the appropriate amount of grease is 1/3 to 1/2 of the total void volume in the bearing. However, depending on the specific situation, sometimes grease should be applied to the edge of the bearing to implement cavity lubrication, such as the wheel hub bearing of a car.
According to statistics, excessive grease is a major cause of bearing lubrication failure. Before each filling, do not add more blindly, but make a scientific calculation based on the requirements and conditions of the equipment, such as speed, size, type, etc., so as to know the amount of oil to be added. If an automatic lubrication system is used, it should be noted that the amount of each filling and the frequency of refueling should be calculated and adjusted to avoid excessive refueling. If the amount of grease added is too large, the friction torque will increase, the temperature will rise, and lubrication failure will occur; if the amount of grease added is too small, reliable lubrication cannot be obtained and dry friction will occur. Generally speaking, the appropriate amount of grease is 1/3 to 1/2 of the total void volume in the bearing. However, depending on the specific situation, sometimes grease should be applied to the edge of the bearing to implement cavity lubrication, such as the wheel hub bearing of a car.
Estimation formula for grease addition: Q=0.005 x D x B
Q——filling amount, unit g
D——bearing outer diameter, unit mm
B——bearing width, unit mm
2. It is forbidden to mix greases of different brands
Since the thickener, base oil and additives used in greases are different, mixing them will cause changes in the colloid structure, increase oil separation, change viscosity, and affect mechanical stability. In addition, in the process of oil change, pay attention to clean up the old oil. New grease cannot be mixed with old grease, even if it is the same type, because the old grease contains a lot of organic acids and impurities. If mixed with new grease, it will accelerate its oxidation and deterioration. Therefore, when changing grease, the old grease on the parts must be cleaned and then new grease is added.
3. Pay attention to the grease change cycle and use process management
Pay attention to regular filling and replacement of grease. When adding and replacing new grease, the waste grease should be squeezed out until the new grease is seen at the grease outlet. The greasing process must be kept clean to prevent mechanical impurities, dust and sand from mixing in.
As the types and quality of grease are constantly improving and changing, when old equipment is replaced with new grease, it should be tested first and then used formally after trial; when replacing new grease, the waste grease should be removed first and the parts should be cleaned. When adding grease, the waste grease should be squeezed out until new grease is seen at the grease outlet.
In addition, when the bearing temperature exceeds 70°C, the interval for adding grease should be reduced by half for every 15°C increase in bearing temperature.
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