Every lubricant poses particular character that meet certain circumstances and function, customers need to comprehend certain lubricant that they employ with.Because lubricating oil can oxidize, consequently can the base oil in grease. When the grease oxidizes, it generally darkens; there is a build-up of acidic oxidation products, just like in other lubrications. These products can have a destructive effect on the thickener, leading to softening, oil bleeding, and leakage. Because grease does not conduct heat easily, critical oxidation can start at a hot point and spread slowly through the grease. This generates carbonization and progressive hardening or crust formation. All things regarded as the effect of oxidation is more harmful in grease than in oil.
The level of oxidation is mainly dependent on the temperature. Here it is good to understand that if a soap-based grease is heated, its penetration raises only very gradually until a certain critical temperature is reached. At this level the gel composition breaks down, and the whole grease develops into liquid. This critical temperature is known as the DROP POINT. Grease, when heated above its drop point and then allowed to cool it generally does not totally regain its grease-like consistency, and its performance subsequently will be unsatisfactory. Therefore, it follows that at no time should the drop point be exceeded. The problem with multi-purpose greases is that at least one of the agents will go beyond its drop point thus adversely affecting the soap onification process. Grease has a highest temperature at which it can safely be used. Therefore, it follows that it must also have a lowest temperature. This lowest temperature is the point where the grease becomes too hard for the bearing, or other greased component, to be used. Again, the base oil of the grease determines the lowest temperature. Obviously, the base oil of the grease for low-temperature service should be made from oils having a low viscosity at that temperature. The temperature limits for apply of greases are therefore, determined by drop point, oxidation, and stiffening at low temperatures.
The level of oxidation is mainly dependent on the temperature. Here it is good to understand that if a soap-based grease is heated, its penetration raises only very gradually until a certain critical temperature is reached. At this level the gel composition breaks down, and the whole grease develops into liquid. This critical temperature is known as the DROP POINT. Grease, when heated above its drop point and then allowed to cool it generally does not totally regain its grease-like consistency, and its performance subsequently will be unsatisfactory. Therefore, it follows that at no time should the drop point be exceeded. The problem with multi-purpose greases is that at least one of the agents will go beyond its drop point thus adversely affecting the soap onification process. Grease has a highest temperature at which it can safely be used. Therefore, it follows that it must also have a lowest temperature. This lowest temperature is the point where the grease becomes too hard for the bearing, or other greased component, to be used. Again, the base oil of the grease determines the lowest temperature. Obviously, the base oil of the grease for low-temperature service should be made from oils having a low viscosity at that temperature. The temperature limits for apply of greases are therefore, determined by drop point, oxidation, and stiffening at low temperatures.
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