Several performances affecting the service life of linear bearing are as follows:

　　1.Cavitation

　　Bearing cavitation is the form of surface damage caused by solid surface contacting with liquid and making relative movement.When the lubricating oil is in the low pressure area of the oil film,bubbles will form in the oil.After the bubbles move to the high pressure area,the bubbles will collapse under the pressure.At the moment of collapse,great impact force and high temperature will be generated.Under the repeated action of this impact force,the solid surface will fatigue and fall off,causing small pits on the friction surface,and then develop into spongy scars.Cavitation often occurs in sliding bearings with heavy load,high speed,and large changes in load and speed;

　　2.Fluid erosion

　　The fluid erosion of linear bearing means that the fluid will cause fluid erosion when the fluid impacts the solid surface violently,which will make the solid surface appear dotted scars,and the surface of this kind of damage is relatively smooth;

　　3.Electrical erosion

　　The electric erosion of bearings refers to the electric spark generated between the friction surfaces of linear bearings due to the electric leakage of the motor or electric appliance,and the dotted scars caused on the friction surface,which is characterized by the damage appearing on the hard journal surface.

　　In order to predict the fatigue life of bearings and judge the remaining life,it is necessary to understand all bearing fatigue damage phenomena,which will take a long time.However,since rolling fatigue occurs under the compressive stress of the contact point,great material changes will occur to achieve the damage.Therefore,in addition to the early cracks on the surface,the chemical effects on the raceway,and the crack propagation before the material change,the fatigue degree of the linear bearing can be judged by detecting the material change.

　　Fatigue failure of linear bearing is a surface form of failure,which is mainly manifested in the initiation,propagation and fracture process of fatigue crack,and the long-term impact of load failure caused by alternating.

　　The cracks are in two aspects:

　　1：From the surface,this is the effect of the external load caused by the plastic deformation on the working surface and the periodic change of the contact stress on the strain-hardened surface of the linear bearing during the rolling contact process,and finally the formation of the surface crack between the inner surface where the small crack develops.Due to the"added lubricant"on the working surface,the open force severely hit the wall and forced the crack forward;

　　2：From the surface layer,under repeated pressure,the contact of the surface will initially produce cracks at a certain depth at the exposed surface,and from the angle of the surface direction to a certain depth,from behind the surface of the contact surface,and beyond the surface,and finally form corrosion stripping,leaving a crater.