Grease lubricated bearing analysis of the low and high temperature environment

Grease lubrication usually applies to the bearing operating temperature lower than the limit temperature grease in the low speed applications. There isn't a antifriction bearing grease can be suitable for all applications. Each only have limited the performance of the grease and features. Grease is composed of base oil, thickener and additive. Bearing grease is usually include use of some metallic soap thickening of petroleum base oil. In recent years, synthetic base oil with organic and inorganic thickener. 26 summarizes typical grease composition table. Table 26. The composition of the grease base oil thickening agent additive in mineral oil grease synthetic hydrocarbon resin material in the silicone oil lithium fluoride, aluminum, barium, calcium complex soap base and without soap ( Inorganic) Microgel ( Clay) PTFE, carbon black, silica gel, no soap base ( Organic) Polyurea compound corrosion inhibitor dye viscous agent metal passivator antioxidant anti-wear extreme pressure additive calcium and aluminum base grease has excellent water resistance, is suitable for the need to prevent moisture intrusion of industrial applications. Lithium grease has many USES and is suitable for industrial applications and wheel bearing. Synthetic base oil, such as esters, organic resin and silicone, when they and common thickening agent and additives are used together, the highest working temperature is usually more than the highest working temperature with oil as base oil. Working temperature range can be from synthetic grease 73 ° C to 288 ° C. Here is with petroleum base oil general features of commonly used thickener. Table 27. For use with petroleum base oil thickener the general characteristics of thickener typical the highest temperature drop point water resistance will be the thickener in table 27 and synthetic hydrocarbon or ester base oil used, the highest working temperature can be increased about 10 ° C. ° C ° F ° C ° F lithium base 193, 380, 121, 250 good compound lithium base 260 + 500 + 149 300 good compound excellent sulfonic acid calcium aluminum 249 480 149 300 299 570 177 350 260 500 149 300 excellent polyurea is good be used for polyurea thickener is lubrication field for more than 30 years the most significant progress. Polyurea grease in a variety of bearing applications show the excellent performance, and in a short period of time, has become a recognized by people is ball bearing lubricant. Low temperature under the condition of low temperature, the size of the grease lubricated bearing starting torque is very important. Some grease only to work properly when the bearing is running, and for bearing's starting causes too much resistance. In some small machine, when the low temperature may be unable to start. In such work environment, requirements to grease has the property of cold starting. If the working temperature range is wide, synthetic grease has obvious advantages. The grease can in - 73 ° C is still under the low temperature of starting and running torque is small. In some cases, these grease in this regard than the lubricant performance is better. About the grease to the point, the starting torque is not necessarily a grease consistency or integrated performance function. The starting torque is more like a particular individual performance is a function of grease, by using the experience to determine. High temperature, high temperature limit of modern grease is usually base oil thermal stability and resistance to oxidation and oxidation inhibitor of the effectiveness of the comprehensive function. The temperature range of the grease is made up of grease thickener drop point and base oil composition. 28 shows the various tables under the condition of the temperature range of the grease base oil. After years of grease lubrication bearing test, the experience method showed that higher temperature every 10 ° C, the service life of the grease will be halved. For example, if a service life of the grease at 90 ° C temperature is 2000 hours, when the temperature rises to 100 ° C, the service life of about 1000 hours. On the other hand, the temperature dropped to 80 ° C, the expected service life can reach 4000 hours.