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The wear of machine parts
Classification of types of wear. At process stage- shivani are influenced by a number of factors. The most important ones are as follows: • the nature and character of friction. The nature is rolling friction or sliding friction, the nature of dry friction or with a lubricant; • the value of specific pressure and the nature of the application loads (static or dynamic); • the speed of relative movement of the rubbing is surfaces; • method of supply, the quantity and quality of lubricants; • the ambient temperature of the work parts; • corrosive environment and the quality of the image available films; • the presence of abrasive material, its quality (hardness) and dimensional characteristics; • the initial state of the friction surfaces; • the degree and nature of removal of wear products; • the shape and dimensions of the rubbing surfaces. The presence of such a large number of factors, provide encompassing the influence on the deterioration process, indicate the complexity of the phenomena occurring in the surface layers. Depending on the impact of these factors when the friction surfaces have in place the following processes: • mechanical (plastic deformation, cutting, scratching); • chemical (oxidation, corrosion); • thermal (temperature effect by friction on the change in the mechanical characteristics of the surface layer); • molecular (diffusion); • EDM. These processes cause the surface layers various types of wear, which established Stan- Darth GOST 27674-88 "Friction, wear and lubrication. Ter- mines and definition". To mechanical abrasion include the following types: abrasive, hydro and gazoobrazovania, hydro and gas erosion, cavitation, fatigue, wear when jamming, wear when fretting. Corrosion-mechanical wear includes oxidative deterioration and wear under fretting- corrosion. EDM wear occurs when the action of the electric current. Mechanical wear occurs as a result of mechanical impacts on the surface- chestnye layers of moving parts. Corrosion-mechanical strength- Kim called wear and tear from mechanical who- actions, together with the chemical or electrochemi- ical interaction of the metal with the working environment. EDM is called erosive wear as a result of the impact of discharges during the passage of the elect- historical current. All of these types of wear occur the work of parts in the car. In real operation conditions of machines is very often there is a conjunction of several types of naseleniya. In such cases, set the leading type, limiting the longevity of the parts, and separate it from other, related types of fracture surfaces, non- significantly affecting the performance of the pairing. The mechanism leading type of wear is determined by as the friction surfaces. Each type of relevant em particular only the surface of ISASI- tion. It is the result of reflection action time personal factors specific for this process to work you friction pair, for example, risks on the friction surface indicate the presence and action of abrasive particles, pow- Ki oxides arise from the action of corrosive media, washing formed under the action of fluid flow or gas, etc. The features of surface friction allow you to set the leading type of wear, and knowledge mechanism and the nature of its flow enable to develop activities to achieve specified long- eternity when performing repair work. |
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