The physical properties of the grease - bearing knowledge influence on mechanical wear

Wear and tear, refers to the movement of vice when relative motion dual surface material on the surface of the work process of constant loss or residual deformation. Between the surface of the wear process is mainly due to the dual mechanical action, sometimes with chemistry. The mechanical action is usually refers to the effect of friction, and chemical action often refers to environmental medium and chemical erosion. Grease lubrication, grease film can reduce wear and prevent the corrosive substance on the surface of the dual access. Fracture is mechanical parts wear, aging and damage and failure of the three main reasons. Only at the beginning of the wear and tear occurred in terms of the phase or mild wear ( Running-in) Is likely to make a smooth surface. So, a lot of machinery, such as car have to get up to speed before put into normal operation. Generally said, after the parts wear, often causing mechanical precision loss and lower efficiency, so need to replace or repair, forcing lower mechanical productivity. In the mechanical work, every year the economic loss caused by wear and tear is astonishing. By one estimate, more than one-third of the world's energy is in the process of all kinds of mechanical energy in various forms of friction loss. Equipment damage due to loss, on the surface of the dual, need to replace the worn parts, so the spare parts and the amount of steel consumption in gross domestic product (GDP), often almost equal to the host for production. Use, including grease, lubricant, can greatly reduce the friction loss, reduce wear and prolong the service life of mechanical parts, which can save energy and reduce consumption of steel. A, exterior appearance is through the intuitive feel to test the quality of the grease one of the most simple way. Such as color, transparency, and uniformity can be visual inspection; Such as the smell and can use the nose to smell out; Such as grease wiredrawing fiber length, degree of hardness and softness, hands out impurities particle size available. Therefore, by appearance inspection, preliminary judgment about the quality of the grease and identify the types of the grease. Sodium base grease is fibrous structure, for example, can pull a long silk, has strong adhesion on the surface of metal. Second, the grease is generally selected drop point, because it has not attached to the parts due to gravity erosion ability. Must know, at what temperature grease will lose this ability. Never flow dynamic to the flow dynamic and grease on the optical properties of the shift is not easy to use macroscopic observation to determine, so direct determination never flow dynamic grease into flow dynamic temperature. This temperature is called drop point. This change of state is contains the characteristics of the grease soap thickeners class, for the soap base grease thickener class, may not have this state changes, but the precipitation of oil drop. Drop point no definite physical meaning, and its numerical owing to the different devices with different heating rates. From the determination of dropping point can be roughly understand the categories of the grease, composition and its use temperature approximation limit, etc. From the point of soap to melt, the use of soap grease should generally low temperature drop point - 20 30℃。 For example, calcium base grease drop point is 75 - Temperature of 95 ℃, its use is about 50 - 70℃。 Table 4 - 1 lists grease temperature drop point and the use of general, the lower limit mainly depends on the chosen base oil at low temperature. The national standard GB/T4929 - 85 is a drop point measurement, grease and ISO/DP2176 equivalent. GB / T3498 - 83 is the grease to find disease point measurement temperature range.