The NSK bearings failure classification problems

The quality of NSK bearings. During the collapse of the bearing box first checks whether lubricating grease are deteriorating, agglomerate, impurities such as this is bad is the important basis of bearing failure reasons. Then inspect the bearing have chewed and wear; Check the bearing inner and outer ring, rolling body, maintains its smoothness and presence of cracks on the surface of the discoloration, rust, peeling, pits, overheating defects such as excessive measurement of bearing clearance; Look for wear bushing hole point desquamate if there are circumstances when a new NSK bearings should be replaced. NSK bearings. Bearing installation bearing inside diameter and shaft, with the outer diameter and the shell is very important when cooperate with too loose fitting surface will produce relatively sliding known as creep. Once produced will creep of wear surface damage shaft or shell and wear powder into the bearing internal heat, vibration and damage. Too much interference will lead to smaller outer diameter or inner ring diameter larger bearing internal clearance. To choose the suitable for use with want to consider the nature of bearing load, size, temperature condition, the rotation of the inner ring outer conditions. NSK bearing contact fatigue failure of contact fatigue failure refers to the work surface under the role of alternating stress and failure. Contact fatigue spalling occurred in bearing working surface, often accompanied by fatigue crack, first of all, from the maximum cyclic shear stress under contact surface, and then extended to form a different flake shape, such as dot to pitting corrosion or pitting spalling, peel into small sheet according to the shallow flaking. Due to spalling surface expands gradually, and often to deep extension, forming deep spalling. Deep spalling is contact fatigue failure of fatigue source. Between the surface of the wear failure wear failure refers to the relative sliding friction lead to constant wear and tear of the working surface of the metal and the failure. Continuous wear will cause bearing parts damaged gradually, and ultimately result in the loss bearing dimensional accuracy and other related issues. Wear may affect the shape change, the increase of fit clearance and working surface morphology change, may affect the lubricant or make its pollution to a certain degree of lubrication function is lost, so that loss of bearing rotating accuracy and will not operate properly. Wear failure is one of the common failure modes of all kinds of bearings, according to the wear and tear is usually divided into one of the most common form of abrasive wear and adhesive wear. Work of abrasive wear refers to the bearing surface between into hard foreign matter or foreign solid particles or abrasive dust on the surface of the metal caused by the relative movement and the contact surface of wear, often cause furrow of abrasion in bearings working surface. Hard particles or other foreign body may come from inside the host, or from the host system adjacent parts sent by lubricating medium bearing inside. Adhesive wear refers to the because of the friction surface microscopic bumps or foreign bodies make the friction surface is uneven, serious deterioration, the condition of lubrication for local friction heat production, easy to cause local deformation and friction surface friction welded phenomenon, serious when the surface of the metal may be the partial melting, contact surface forces from the local friction welding points on the matrix will be torn and increase the plastic deformation. This kind of adhesive - — Tear - — Adhesive cycle constitutes the adhesive wear and tear, in general, mild adhesive wear is called a scratch, serious adhesive wear called occlusion. Failure of bearing failure of the main reason is that defects and overload two factors. When the loads more than material strength limit fracture caused by parts called overload fracture. Overload reason mainly is the main engine failure or improper installation. Bearing parts of micro crack, shrinkage cavity, bubbles and large foreign impurities, overheating organizations and local burns and other defects during the impact overload or violent vibration will cause fracture in defect, known as defect fracture. It should be pointed out that the bearing in the process of manufacturing, for raw materials into the factory reinspection, forging and heat treatment quality control, process control through instrument analysis of the existence of the above defects and correct still must strengthen control in the future. But in general, usually bearing fracture failure of most for overload failure. NSK bearing clearance change failure at work, because of the influence of the external or internal factors, change the original fit clearance, lower accuracy, and the change of 'killed' called clearance failure. , large amount of the external factors such as interference of installation does not reach the designated position, temperature rise caused by the expansion, instantaneous overload, etc. , internal factors such as residual austenite and the residual stress in a state of flux and so on all is the main reason for the failure caused by clearance changes.