Research results and experience have shown that certain crystalline precipitates produced in the grease will gradually become smaller, melted and re-dispersed into the grease at a certain temperature. In order to verify this statement, the old bearings (including original grease) were treated with recovery technology, and the old bearings were placed in an oven at 85°C for 2 hours at a constant temperature. After they were taken out and cooled to room temperature, the vibration value of the bearing was measured immediately. After that, let the heated bearing stand at room temperature for a period of time (16 days for the new bearing and 13 days for the old bearing), and then measure the vibration value to further verify the phenomenon of grease denaturation. according to the test results:

(1) After the heating treatment, the average value, maximum value and minimum value of vibration of the old bearing decreased significantly. Among them, the average vibration of A and C bearings is reduced by 1.1dB, and the average vibration of B bearings is reduced by 2.5dB.

(2) After standing for a period of time, the average value, maximum value and minimum value of vibration of all bearings rebounded significantly. Among them, the vibration average value of the old bearing B has the largest recovery, which is 3.4dB higher than that after the heating treatment.

Take out the grease in the bearing and observe its aggregation state with a microscope. It is found that there are many translucent crystals inside the grease, the shape is irregular circle, the maximum diameter of the particles is about 40μm, and most diameters are about 10μm. These particles are large in size, large in number, and have a certain hardness, just like mechanical impurities, which lead to an increase in the vibration value of the bearing.

conclusion:

(1) The precipitation of denatured crystals of grease in the bearing is the main reason for the increase of bearing noise and vibration value. After the recovery heating treatment, the vibration and noise of the bearing were significantly reduced, but the vibration value of the bearing increased significantly after standing for more than ten days, indicating that the storage stability of the grease was poor.

(2) The denaturation process of the grease is reversible.

(3) The formation reasons and components of crystalline precipitates in grease need to be further analyzed.

The formation reasons and components of the crystalline precipitates need to be further analyzed.