Reduce the damage type sliding bearing in NSK
1 scratch (grain wear two body)
Hard particles with a diameter of moving contact and friction surface, the particles and the metal surface contact stress is low, they underline the linear scar on the bearing surface; hard particles embedded in the surface of shaft bearing surface will also draw linear scars, are referred to as scratch. Scratch the genera and two body abrasive wear, linear scar direction and axis movement direction.
Rupture of the lubricating film, the surface of shaft hub peak will scratch pad, appeared many linear scar, it is also the two body abrasive wear.
Hard particles embedded bearing surface and shedding, scratches spot scars.
The particles are mostly ferrite powder and sand.
Scratches resulting in friction surface roughness, which reduces the carrying capacity of the lubricating film, and the formation of new can scratch hard particles friction surface and wheel peak, resulting in vicious spiral.
2 (three body abrasive wear)
Small hard particles into the NSK bearing clearance, wavering between the two friction surface, resulting in high in the friction surface contact stress, consisting of three body abrasive wear, similar to the abrasive action, make the bearing and shaft wear surface. Between hard particles and the friction surface of the friction surface of high contact stress of ductile metal plastic deformation or damage, the friction surface of brittle metal brittle cracking or spalling.
Wear scar of wear particle is linear, the direction of motion direction is consistent with the shaft diameter.
When the edge contact, lack of lubrication oil or oil film rupture will generate abrasion violent. Abrasive wear will cause the shaft diameter and (or) bearing geometry size and shape changes, loss of precision, NSK bearing clearance is increased, the performance of sliding bearing in NSK life expectancy before a sharp deterioration.
3 seizure (glue)
The rupture or lack of oil lubrication condition, friction factor leads to the generation of a lot of friction heat, NSK bearing temperature rise. At high temperature, a friction surface of the low melting point metal for softening and adhesion in another friction surface, along with the shearing axis diameter rotary motion formation, adhesion of metal from the original surface, transfer to another friction surface, causing friction surface as obvious concave and convex. This damage is adhesive wear.
Appear bite stick, friction increases rapidly, NSK bearing temperature rise further, forming a vicious spiral. When the adhesion of serious, dynamic rotation shaft diameter can no longer be sheared viscosity node, will enable the axis motion termination, commonly known as "axle", NSK bearings thoroughly damaged.
4 fatigue wear
Fatigue wear and fatigue damage. In the repeated use of cyclic loading, in a direction perpendicular to the slide direction on friction surface, fatigue crack, crack perpendicular to the bearing surface to deep development, to the lining layer and the backing surface, and the friction surface extending parallel to, finally material from the friction surface is peeling off, causing cavernous injury.
5 peel
Making bush, if the lining layer and the backing binding or binding side, in the NSK bearing in operation, under load, local lining materials will be peeled from the bush. Peel and fatigue spalling is somewhat similar, but the fatigue spalling pits surrounding irregular, with peeling pit surrounding caused relatively smooth. 6 corrosion
Lubricating oil in the course of continuous oxidation, oxidation of organic acids produced weak often, it on NSK bearing materials especially the casting of copper lead alloy of lead corrosion, which is characterized in lead spotty off, make the rough surface.
Inorganic acid strong more prone to corrosion of steel shaft neck surface.
Tin based bearing alloy NSK in tin is oxidized, a layer of SnO2 and SnO composed of black hard covering layer is formed on the surface of the bearing bush, hardness in the range of 200 ~ 600HS. The covering layer is extremely harmful to the NSK bearing, it is very hard, can scratch the shaft neck surface, and make the NSK bearing clearance becomes small.
7 erosion
(1) the cavitation
Cavitation is a form of damage to the surface of solid surface contact with the liquid and the relative movement generated by the.
When the lubricating oil in the oil film pressure zone, oil will form a bubble, bubble motion to the high-pressure zone, under pressure of bubble collapse, great impact and high temperature in the collapse of the moment, repeated use of solid surface in the impact force, material fatigue fall off, the friction surface the small pit, and then developed into a sponge.
Heavy load, high speed, and the load and speed changes in the larger sliding NSK bearing, often cavitation.
(2) fluid erosion
Fluid fierce impact solid surface can cause fluid erosion, the spot scar on solid surface, the surface of this damage is smooth.
(3) the electrical erosion
Because the motor or electric leakage, electric spark is generated on the friction surface, causing punctate scar in the friction surface, which is characterized in injury reciprocating in stiffer shaft neck surface.
8 the fretting wear
In the lining layer and the backing, combined with the bearing and NSK bearing surface, because the micro vibration between the metal surface (slip) combination and oxidation, the formation of adhesive wear, oxidation wear abrasion (corrosion) and the 3 forms of abrasive wear, called the fretting wear, it will cause the scar on the node point the bonding surface.
