One is a thin-walled SKF bearing with a bush, which is similar to a tile, commonly known as a bush; the other is a bush, also known as a copper sleeve, which is a hollow cylinder. Bushing thin-walled SKF bearings are mainly used to support the crankshaft and connecting rod of the engine; bushings are mainly used to support camshaft journals and piston pins. This article mainly describes the bush-type thin-walled SKF bearing (bearing bush).
Early forms of damage
During normal use of SKF bearings, due to the gradual wear and tear until the final loss of working capacity and the end of its service life, this natural damage is inevitable. However, if the SKF bearing wears prematurely or has various damages due to improper engine assembly and adjustment, poor lubricating oil quality or poor use conditions, it is an early damage caused by man. Early damage not only greatly reduces the service life of SKF bearings, but also affects the normal operation of the engine. According to the long-term experience of diesel engine maintenance, the common forms of early damage of sliding SKF bearings include mechanical damage, SKF bearing cavitation, fatigue pitting, corrosion, etc.SKF Bearing 619/8-2RS1 online, click here to buy it.
(1) Mechanical damage
The mechanical damage of sliding SKF bearings refers to the presence of groove marks on the alloy surface of the bearing bush to varying degrees. In severe cases, metal peeling occurs on the contact surface and large-area messy scratches; in general, contact surface damage and ablation simultaneously exist. The main cause of mechanical damage to SKF bearings is that it is difficult to form an oil film on the surface of SKF bearings or the oil film is severely damaged.
(2) SKF bearing cavitation
Sliding SKF bearings undergo plastic deformation and cold work hardening under the repeated action of cylinder pressure shock loads, and locally lose their deformability, gradually form grains and continue to expand, and then as wear debris falls off, cavities are formed in the loaded surface layer. . Generally, when cavitation occurs in the bearing bush, pits appear first, and then the pits gradually expand and cause cracks at the interface of the alloy layer. The cracks expand in the parallel direction of the interface until they peel off. The main reason for the cavitation of sliding SKF bearings is that the sudden change of the cross-section of the structural elements such as the oil groove and the oil hole causes the oil flow to be strongly turbulent, and bubbles are formed in the turbulent vacuum area of the oil flow, and then the bubbles collapse due to the increase in pressure. Cavitation. Cavitation generally occurs in the high-load area of SKF bearings, such as the lower bearing bush of the main SKF bearing of the crankshaft.
(3) Fatigue pitting
SKF bearing fatigue pitting refers to the overheating of the SKF bearing and the excessive clearance of the SKF bearing due to the overload of the engine, resulting in fatigue damage, fatigue pitting or fatigue loss in the middle of the SKF bearing. This kind of damage is mostly caused by overload, SKF bearing clearance is too large, or the lubricating oil is not clean, and foreign matter is mixed in it. Therefore, care should be taken to avoid SKF bearing overload work and not run at too low or too high speed; adjust the engine to a stable state when idling; ensure the normal SKF bearing clearance to prevent the engine speed from being too high or too low; check, Adjust the working conditions of the cooling system to ensure that the working temperature of the engine is appropriate.
(4) Corrosion of SKF bearing alloy
SKF bearing alloy corrosion is generally caused by impure lubricating oil. The chemical impurities (acid oxides, etc.) in the lubricating oil oxidize the SKF bearing alloy to generate acidic substances, causing part of the SKF bearing alloy to fall off, forming irregular micro-cracks Or small pits. The main reasons for the corrosion of SKF bearing alloys are improper selection of lubricants, poor corrosion resistance of SKF bearing materials, or rough engine operation and excessive temperature.
(5) SKF bearing melting
There is a small raised metal surface between the journal and the SKF bearing friction pair that directly contacts, resulting in local high temperature, and in the case of insufficient lubrication and poor cooling, the SKF bearing alloy will be blackened or partially melted. This failure is often caused by the tight fit between the journal and the SKF bearing; insufficient lubricating oil pressure can easily burn the SKF bearing.
(6) SKF bearings go outer circle
The outer circle of SKF bearing means that the SKF bearing rotates relatively in the seat hole. After the SKF bearing goes outside the circle, it will not only affect the heat dissipation of the SKF bearing, and easily cause the alloy on the inner surface of the SKF bearing to ablate, but also damage the back of the SKF bearing, and burn the SKF bearing in severe cases. The main reason is that the SKF bearing is too short, the tenon is damaged, and the processing or installation does not meet the specifications.We provide SKF Bearing 1209 EKTN9, contact us to buy it.
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