What are the common problems of oil-free bearing?

What is the oil free self-lubricating bearing made of:

Oil-free self-lubricating bearings have strong wear resistance, while high-force brass has high strength, high hardness and strong chemical resistance.
High strength brass is used as the matrix, and embedded radial arranged orderly cylindrical polymer filler for friction materials, superiority lies in its made of copper alloy and non-metallic antifriction material has the respective complementary advantages, not only has high bearing capacity, and break through the boundaries of generally depends on the oil film bearing grease lubrication, achieve no oil lubrication, the embedded solid lubrication easy lubrication film formation,It improves the friction and wear performance greatly and is stable, reliable and cost-effective.

We tell you that oil-free self-lubricating bearings should be dealt with in time when the situation arises:

Oil-free self-lubricating bearings are mainly used in the case of high speed. The higher the speed, the lower the viscosity of the bearing; The greater the load, the higher the viscosity of the bearing. The higher the temperature, the higher the bearing viscosity. Bearings belong to precision parts, so it requires a very cautious attitude when using. Even high-performance bearings can not achieve the expected performance effect if they are used improperly, and they may cause bearing damage. It should be noted that the grease of oil-free self-lubricating bearings should be replaced once every six months or so, and it is better to replace it once every three months under poor working conditions.

What mistakes should we pay attention to when using oil-free self-lubricating bearings?

Blind choice of lubricants: lubricants lubricate, cool, clean and seal.The quality of lubricating oil is directly related to the service life of the engine.Black oil is oil deterioration: engine oil is working under harsh high temperature conditions, easy to oxidation and deterioration, acid substances and superimposed into polymer sediments, so as to destroy lubrication.

Diesel vehicles use gasoline car oil: oil has gasoline engine oil and diesel engine oil.Although gasoline engine and diesel engine work under the same conditions of high temperature, high pressure, high speed and high load, there are still great differences between them.

In the process of using oil-free bearings, it is inevitable that some conditions will arise. The first failure modes of oil-free bearings mainly include: cracks, plastic deformation, wear, corrosion and fatigue. Under normal conditions, the primary oil-free bearing is the main factor of internal fatigue influence: hardness, strength, strength, wear resistance, corrosion resistance, internal stress (outside service conditions).

Let you know what are the common problems of oil-free bearings?

1. Martensite in quenched steel of oil-free bearing

Original arrangement of high carbon chromium steel: granular pearlite

Quenching + low temperature tempering: the carbon content in quenched martensite m is obviously higher than that of bearing, which affects the mechanical function of steel

When the carbon content of quenched m of GCr15 steel is 0.5% ～ 0.56%, the inductive mechanical function with the strongest failure resistance can be obtained.

2. Retained austenite in quenched steel of oil-free bearing

After normal quenching, high carbon chromium steel can contain 8% ～ 20% AR (retained austenite).

The content of AR in bearing parts should be appropriate.

The hardness and the life of the steel increase with it. If it spontaneously transforms into martensite and then decreases after reaching the peak value, the favorable effect of AR is that under the stable condition of AR, the resistance of the steel will decrease sharply and become brittle.

When the axial load is small, a small amount of deformation occurs in AR, which not only reduces the stress peak, but also strengthens the deformed AR by processing strengthening and stress-strain induced martensitic transformation. The effect of increasing the amount of AR on the contact fatigue life is reduced. When the axial load is large, the larger plastic deformation of AR and the matrix will partially occur stress convergence and fracture, so that the life decreases.

3. Residual stress of oil-free bearing after quenching and tempering

The fatigue strength increases with the increase of the residual compressive stress on the surface (excessive residual stress may cause deformation of the parts). When the residual internal stress on the surface is tensile stress, the fatigue strength decreases.

After quenching and low temperature tempering, the bearing parts still have large internal stress.

4. Undissolved carbides in quenched steel

The quantity, description, size and distribution of undissolved carbides in quenched steel are affected by the chemical composition of the steel and the original arrangement before quenching, and by the austenitizing conditions.

When bearing, especially when the carbide is non spherical, the stress converges with the matrix and cracks occur, which will reduce the resistance and fatigue resistance.

Effect of quenched undissolved carbides on the function of steel

The carbon content and AR content and dispersion of quenched martensite are affected, which has additional effect on the function of steel.

Too much undissolved carbide in quenching is harmful to the mechanical function and failure resistance of steel.

It is necessary for bearing steel to have a few undissolved carbides after quenching. In order to obtain fine grain cryptocrystalline martensite, it is required that the undissolved carbides should be small (quantity is small), small (scale is small), uniform (the difference between size and size is very small, and the distribution is uniform), and round (each carbide is spherical).

Reducing the carbon content of bearing steel is one of the ways to improve the service life of parts.

5. Impurity content of oil-free bearing steel

Impurities: nonmetallic dopants harmful elements (acid soluble) if the oxygen content is higher, it is necessary to reduce the oxygen content of steel for production. Exception: the more oxide dopants, the more impurities in steel. The influence of impurities on mechanical function and anti failure ability of parts is related to the type, nature, quantity, size and shape of impurities. Generally, it has the effect of reducing resistance, plasticity and fatigue life. About working under high stress Because of the ellipsoidal shape of MNS dopant in steel, the harmful oxide can be wrapped in the bearing parts. The effect of MNS dopant on fatigue life is small and even may be beneficial.