Greases are formed by mixing the base oil with a thickener to form a grease. Krytox® greases use a special high thickening efficiency, low molecular weight PTFE with very small particle sizes as its thickener. This is one of the most thermally stable thickeners for high-temperature, long-term greases. The lower thickener content in the grease maximizes the oil for improved grease life.
Greases can be formulated with different viscosity oils to handle different temperatures and load conditions. High viscosity oils can be used in greases for high temperatures or heavy loads or low speed applications. Low viscosity oils can be used in greases where low temperature properties are important or speeds are higher. Lower amounts of thickener form softer or more fluid-like greases. Higher thickener levels form harder, stiffer greases. Additives are often added to the grease to enhancenticorrosion protection, raise load carrying ability, or help reduce wear.
Rolling Bearings Krytox® greases and oils provide a thick lubricating film for bearings. This film reduces metal-to-metal contact in the bearings, resulting in superior load carrying capability.
Before adding Krytox® to a bearing, the bearing should be cleaned of all existing greases, oils, or preservative oils used to protect it during storage. If left in the bearing, these hydrocarbon oils can form carbon deposits at higher temperatures, which may accelerate bearing failure. Chlorinated solvents should not be used, because they can leave chlorine that can cause corrosion. If a bearing has previously been packed with another grease, mechanical agitation or an ultrasonic bath should be used to be sure of removing all of the grease.
After the bearing surfaces are clean, they should be lubricated/wiped with Krytox® and properly stored to prevent corrosion. If they are not going to be packed with Krytox® immediately, or if they are going to be in storage for an extended period, they can be dipped in a solution of Krytox® oil and Krytox® fluorosurfactant to coat the surface and protect against rust.
Proper lubrication is achieved by using the correct amount of grease. Too little grease in the bearings causes premature failure. Too much grease at the initial fill or during relubrication can cause overheating of bearings that are running at medium to high speed, resulting in bearing failure. The amount of grease put in the bearing depends on the application and operating speed. For applications such as conveyor rollers and low-speed machinery with DN values (inner race ID in mm x rpm) below 50,000, the bearing can be filled to capacity. For mediumspeed applications, i.e., DN 50,000-200,000, the bearing can be filled 50-70%. For higher-speed systems, the fill is typically 30-40%. Some extreme-speed special applications have grease fills of only 10-15% (see Speed Factor for definition of DN values). Because Krytox® is heavier than hydrocarbon lubricants, its higher density must be considered when determining the fill quantity by weight.
Grease fittings should be changed to a different style, such as button-head or pin type, to ensure that another type of grease is not accidentally put into the bearing. A dedicated grease gun that matches the fitting should be used.
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