1 scratch ( two-body abrasive wear ) Hard particles in contact with the shaft along with the movement of the friction surface, which is the lower surface of the contact stress of the metal particles , they draw on the pad surface of the linear wound ; semi- hard particles embedded in the surface of the pad on the surface of the shaft will draw the line scars are known as scratching. Scratch is a two-body abrasive wear, consistent with the direction of the linear scars shaft movement.
Lubricant film rupture, the peak shaft hub will also scratch the surface of the bush , there are many linear scars, it is also the two-body abrasive wear .
Hard particles embedded in the bearing surface and fall off, causing punctate scars scratched.
Most of these particles are iron powder and sand . Scratching leads to friction surface roughening , thereby reducing the carrying capacity of the lubricant film , and will form a new hard can scratch the surface of the particles and the friction wheels peaks , resulting in a vicious cycle. 2 ( three-body ) abrasive wear Into the bearing gap small hard particles , wandering between the two friction surfaces , the contact stress in the high friction surface to form three-body abrasive wear , similar abrasive , wear of the pads and the shaft surface . High contact stress between the hard particles and the friction surface of the friction surface of the plastic deformation of the ductile metal or fatigue damage, so that the friction surface of the brittle metal or brittle flaking occurred .
Abrasive wear scars also linear direction is also consistent with the direction of shaft movement.
When the edge contact , lack of lubrication or film rupture , etc. will produce severe abrasive wear . Abrasive wear will cause shaft and ( or ) bearing geometry and shape change , the loss of precision , bearing clearance increased, so that the sharp deterioration in the performance of the sliding bearings before life expectancy.
3 seizure ( glued ) In the lubricating oil film rupture or starvation state , a large coefficient of friction results in a large amount of frictional heat , the bearing temperature. At high temperatures, a low melting point metal friction surface adhesion by softening the friction surface on the other , the rotary shaft with shear movement formed from the original surface of the metal adhesion from the transfer to the other friction surface , causing significant friction surface convex pits and scars . This damage is adhesive wear .
Seizure occurs when a sharp increase friction bearing temperature rises further, creating a vicious cycle . When adhesion serious power shaft rotation is no longer able to cut open the bonding point, shaft movement will cause the termination , commonly known as the " axle " , bearing completely damaged.
4 . Fatigue wear Fatigue wear , also known as fatigue damage . Under the effect of repeated cyclic loading in a direction perpendicular to the sliding direction of the friction surface fatigue cracks, cracks develop in the depths of the vertical surface of the pad , the backing layer and the joint surface , the friction surface extending parallel to go , Finally, the friction material is peeled from the surface down , causing a crater-like damage.
5. Stripping When manufacturing the pad , when the backing layer and the binding force is insufficient or poor bonding , the bearings during operation , under the effect of the load , partial lining material is peeled from the pad . Peel and fatigue spalling somewhat similar, but fatigue spalling pits surrounding irregular , combined with stripping pits caused by poor perimeter relatively smooth . 6 Corrosion Lubricants in use constantly oxide, often produce weak organic acids, especially lead bearing material it cast copper lead alloy corrosive , characterized by spotty off the lead , so that the surface becomes rough.
Strong inorganic acid corrosion of steel more journal surface . After the tin-based bearing alloy of tin is oxidized to form a layer on the pad surface of SnO and SnO2 black hard coating layer composed of hardness in the range of 200 ~ 600HS . The cover layer is very harmful to the bearing , it is hard and can scratch the surface of the journal , and to the bearing gap becomes smaller.
7 . Erosion ( 1 ) cavitation Cavitation damage in the form of the solid surface in contact with the liquid surface and the relative movement generated .
When the lubricant film in the area of ??low pressure , the oil will form a bubble , the bubble movement to the high pressure zone at a pressure of the bubble collapse , the collapse at the moment have a great impact force and high temperature , solid surface in action under repeated impact, material fatigue off, the friction surface appear small pits , and then developed into a sponge -like scars.
Heavy duty , high speed, and large changes in load and speed plain bearings , often cavitation .
( 2 ) fluid erosion Fluid intense shock to the solid surface can cause fluid erosion, punctate scars appeared to make a solid surface , such damage is relatively smooth surface .
( 3 ) Electric Erosion As the motor or electrical leakage, electric discharge generated between the friction surfaces , causing scratches on the dot friction surface , characterized in that damage occurs on the hard reciprocating journal surface .
8 Fretting And the backing layer , combined with the bearing surface of the pad , since the micro-vibration ( slip ) between the metal surface and the combined effects of oxidation , forming the adhesive wear, oxidation ( corrosion ) and abrasive wear in the form of three kinds of composite wear, fretting wear is called , it will result in a combination of point-like scars surface.