Common quality defects of KOYO imported bearing parts after heat treatment

Common quality defects of KOYO imported bearing parts after heat treatment include: quenching microstructure superheat, underheating, quenching crack, insufficient hardness, heat treatment variant, surface decarburization, soft point.

Overheat

Overheating of the microstructure after quenching can be observed from the rough mouth of KOYO imported bearing parts.

However, in order to correctly judge the degree of overheating, it is necessary to observe the microstructure. If coarse needle-shaped martensite appears in the quenched structure of gcr15 steel, it is quenched and superheated. The formation may be caused by excessive heating of the quenching heating temperature or the heating temperature is too long; or it may be due to the serious banding of the original structure, forming a local martensite needle-like coarse in the low carbon zone between the two zones. Cause local overheating. The retained austenite increases in the superheated structure, and the dimensional stability decreases. Due to the overheating of the quenched structure, the crystal of the steel is coarse, which leads to a decrease in the toughness of the part and a decrease in the impact resistance. The life of the KOYO bearing is also reduced. Excessive heat can even cause quenching cracks.

2. Underheat

Low quenching temperature or poor cooling will produce a tortite structure exceeding the standard in the microstructure, called underheated structure, which will reduce the hardness and sharply reduce the wear resistance, affecting the life of KOYO bearings.

3. Quenching crack

The crack formed by KOYO imported bearing parts due to internal stress during quenching and cooling is called quenching crack. The causes of such cracks are: the heating temperature is too high due to quenching or the cooling is too fast. The thermal stress and the mass of the metal change the tissue stress greater than the fracture strength of the steel; the original defects of the working surface (such as micro cracks or scratches on the surface) or internal defects of the steel (such as slag inclusions, severe non-metallic inclusions) , white spots, shrinkage holes, etc.) stress concentration during quenching; severe surface decarburization and carbide segregation; insufficient firepower or timely tempering after quenching; excessive cold stress caused by previous processes, forged folding, deep Turning tool marks, sharp edges and corners of oil hooks.

4. Heat treatment deformation

KOYO imported bearing parts have thermal stress and tissue stress during heat treatment. These internal stresses can be superimposed or partially canceled. It is complex and variable because it can follow heating temperature, heating speed, cooling method, cooling rate, The shape and size of the part change, so heat treatment deformation is inevitable. Knowing and mastering the changing laws can make the deformation of KOYO imported bearing parts (such as ellipse of the sleeve, large size increase, etc.) in a controllable range, which is conducive to the production. Of course, mechanical collisions during heat treatment can also cause deformation of the part, but this deformation can be reduced and avoided with improved operation.

For more information and purchase please visit: https://www.supplyforever.com

Introduction to the cause of corrosion of IKO oil-free bearings and methods for preventing corrosion

Oil-free bearings use water-soluble cutting fluids, and users must work harder on machine maintenance and management to control erosion and even eliminate erosion. In order to prevent water from eroding the metal surface, the machine tool should always be fully lubricated and greased on important parts of the machine tool.

Oil-free bearings can have a long life under accurate use. If the damage is too early, it may be caused by improper selection, improper use or poor lubrication.

Therefore, when installing IKO bearings, we need to record the type of machine, the installation location, the premise of use and the nearby cooperation. Through research to summarize the type of bearing damage, the use environment when the problem occurs, to avoid similar situations happen again.

Correctly control the concentration of the cutting fluid. When the machine is shut down, use the cutting fluid to clean the surface of the machine, and open the machine cover to dissipate the humid air in the working area of ​​the machine. To prevent the occurrence of electrical corrosion, a layer of waterproof grease should be applied to the metal surface. Moreover, the machine tool should be grounded strictly. It is not enough to ground the electrical cabinet only. To avoid the breeding and breeding of bacteria, the cutting fluid should be cleaned or replaced on time, the chips should be removed in time, and soft water (pure water with low mineral content) should be used. Diluted the cutting concentrate.

In addition to excellent quality, oil-free bearings are also very precise parts. They are high-performance bearings. If they are used improperly during use, they will not achieve the expected functional effects, and it will easily damage IKO bearings. I have definitely paid attention to it.

First, the use of the installation should be taken seriously and do not agree to strong stamping, do not answer the application of vertical tapping bearings, do not allow to pass the pressure through the moving body.

Second, use appropriate and correct installation tools to use special tools as much as possible, and try to avoid the use of cloth and short fibers.

Third, try to keep the bearing and its surrounding environment clean. Even if the visible dust that is invisible to the naked eye enters the bearing, it will increase the wear, vibration and noise of the IKO bearing.

Fourth, to prevent the corrosion of IKO bearings When taking the bearings directly by hand, you should wash the liquid on your hands and apply high-quality mineral oil before handling. In the rainy season and summer, pay special attention to rust prevention. Under certain special operating conditions, oil-free bearings can achieve longer life than traditional calculations, especially at light loads. These special preconditions are that when the moving surface (track and moving parts) is effectively separated by a lubricating film and the surface damage caused by the contaminants is restricted. In fact, under the premise of ideal, the so-called permanent IKO bearing life is possible.

For more information and purchase please visit: https://www.supplyforever.com