With the increasingly stringent requirements on the noise performance of precision bearings in various industries, low noise is an important indicator to measure the quality level of bearings. Whether the bearing can run quietly or not largely determines whether the equipment can run smoothly. Improving the machining accuracy and installation accuracy of the bearing can improve the noise. However, with the advancement of processing technology, it is more and more difficult to reduce the noise of the bearing by improving the processing accuracy, so the noise reduction performance of the bearing grease has become particularly important.
Performance aspects of low noise performance (1) Grease with low vibration value can reduce the noise of the bearing and improve the quality level of the bearing; (2) High cleanliness grease can avoid bearing noise caused by wear particles. Low noise grease needs to improve the noise caused by factors such as itself or external load by optimizing the structure of the grease and improving the performance of the grease. The main factors affecting the noise performance of grease are Base Oil, thickener and its fiber structure, additives and cleanliness of grease.
1. Base Oil Within a certain range, the noise characteristic of the grease with higher base oil viscosity is better, otherwise the noise characteristic is worse; but beyond a certain range, the noise of the grease increases with the increase of the base oil viscosity. Different types of base oils have different effects on the noise of lubricating greases. Greases prepared with naphthenic oils or blended oils of naphthenic oils and synthetic esters have better noise characteristics, while those prepared with PAOs or diesters The prepared grease has poor noise characteristics. 2. Thickener The influence of thickener on the noise characteristics of grease is mainly manifested in the fiber structure of the thickener. According to the viscosity of the base oil and the fiber structure of the thickener, the grease can be divided into agitation type grease and groove type grease. Stirring greases have low base oil viscosity and short thickener fibers; grooved greases have high base oil viscosity and slender thickener fibers. Greases with short thickener fibers are more conducive to reducing the noise of the bearing than those with long thickener fibers. Low-noise bearings running at high speed and low temperature are generally lubricated by greases with short thickener fibers. 3. Additives Generally speaking, additives easily destroy the colloidal structure of grease, and different additives have different effects on the noise characteristics of grease. The size of the additive particles is within a certain range to help reduce the noise of the bearing and improve the noise characteristics of the grease. Adding a certain amount of silica and titania nanoparticles can reduce the noise of the grease, but it has little effect on the polyurea grease. Polymer additives can increase the thickness of the oil film and can play a role in reducing noise. 4. Cleanliness In addition to the above factors, cleanliness also has a certain influence on the noise characteristics of lubrication. The size, hardness and shape of impurities in the grease will affect the noise characteristics of the grease. For greases with different thickener fiber structures, impurities have different influences on bearing noise. For grease with short thickener fibers, impurities are easy to repeatedly enter the friction contact area of the bearing, increasing the bearing noise; while for grease with long thickener fibers, there are fewer opportunities for impurities to enter the lubricating interface, and the impact on bearing noise is small. Therefore, greases with short thickener fibers have higher requirements for cleanliness than those with long thickener fibers.
