The shaft diameter prevents direct adhesion and boundary lubrication when in direct contact with the bearing pads. The material factors that affect the frictional compatibility of the friction pair are:
(1) The degree of difficulty in forming an alloy by metallurgical materials.
(2) Affinity of materials and lubricants.
(3) The friction factor of the auxiliary material in the non-lubricated state.
(4) The microstructure of the material.
(5) Thermal conductivity of the material.
(6) The size of the surface energy of the material and the characteristics of the oxide film.
2. Embedding The material allows the ability of external hard particles to be clamped in the lubricant to prevent scratching or (and) abrasive wear. For metal materials, if the hardness is low and the modulus of elasticity is low, the embedding property is good, and the non-metal material is not necessarily, for example, carbon graphite, the modulus of elasticity is low, but the embedding property is not good. KOYO bearings usually use a softer material to form a frictional web with a harder material. Generally, a softer material is used as the bearing pad.
3. Running-in property In the running-in process of shaft diameter and bearing bush, the shaft diameter and bearing bush machining error, coaxiality error and surface roughness parameter value are reduced to make the contact uniform, thereby reducing the friction and wear rate.
4. Friction Compliance The material compensates for the initial poor fit of the sliding friction surface and the flexural performance of the shaft by the elastoplastic deformation of the surface layer. Materials with low modulus of elasticity have better compliance.
5. Abrasion resistance The ability of the secondary material to resist wear. Under the specified wear conditions, the wear resistance is indicated by the wear rate or the degree of wear and the reciprocal of the amount of wear.
6. Fatigue resistance The ability of a material to resist fatigue damage under cyclic loading. At the temperature of use, the strength, hardness, impact strength and tissue uniformity of the bearing material are important to combat fatigue. Materials with good running-in and good insertability usually have poor fatigue resistance.
7. Corrosion resistance The ability of the material to resist corrosion. Lubricating oils will gradually oxidize when used in the atmosphere, producing acidic substances, and most of the lubricating oils also contain extreme pressure additives, which will corrode KOYO bearing materials. Therefore, KOYO bearing materials need to have corrosion resistance.
8. Cavitation resistance In the state where the solid moves relative to the liquid, when the bubble in the liquid ruptures near the solid surface, a local impact high pressure or a local high temperature is generated, which will cause cavitation wear. The ability of a material to resist cavitation wear is referred to as cavitation resistance. Generally, copper-lead alloys, KOYO bearing alloys, and aluminum-zinc-silicon alloys have good cavitation resistance.
9. Compressive strength The ability to withstand a unidirectional load without being crushed or the size does not change.
The criteria for judgment vary depending on mechanical properties and importance, inspection period, and the like. KOYO bearings must not be reused if they have the following damage and must be replaced.
1) Breakage and defects of linear bearing components.
2) Peeling of the rolling surface of the raceway.
Bearing fault identification method
It is very important to improve the productivity and economy by identifying or predicting the failure of the running linear bearing without disassembly inspection.
The main methods of identification are as follows:
1) Identify by sound
It takes a lot of experience to identify by sound. Must be fully trained to be able to identify bearing sounds and non-KOYO bearing sounds. To this end, the work should be carried out by a dedicated person. The sound of the bearing can be clearly heard by attaching a listener or a listening stick to the housing.
2) Identification by operating temperature
This method is a comparative identification method and is limited to occasions where the operating state does not change much. For this purpose, continuous recording of the temperature must be carried out. In the event of a fault, not only does the temperature rise, but irregular changes can occur.
3) Identification by the state of the lubricant
Sampling analysis of the lubricant is judged by whether or not the degree of contamination is mixed with foreign matter or metal powder. This method is particularly effective for KOYO bearings or large bearings that cannot be observed close.
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