Selecting an appropriate quenching medium is particularly important. It determines the bearing microstructure and properties after quenching. Quenching medium usually has solid, liquid and gas three forms.
Deep groove ball bearings in heat treatment furnace heated to fully austenitic, for obtaining the required organization and performance, it need for a quenching treatment. Workpiece after cooling to obtain martensite organizations, its cooling rate must be greater than the critical cooling rate, but too cool and too fast will make volume shrinkage and microstructure transformation violent, caused a great deal of stress. Thus conditions for martensitic “f” should enable the cooling rate as low as possible.
NTN bearings after correct repairing are the same performance with new bearings. The precision parameter such as its clearance can meet the requirements of new bearings. It is important to understand and identify damage degree to choose the correct rehabilitation program. For example, surface finishing treatment can clear some minor damage, but could not clear the real fatigue and the debris or wear caused by depression. Therefore, if only for the NTN bearing surface finishing treatment, generally it is not suitable for serious injury deep groove ball bearings. And if fully repair remanufacturing technology, the fatigue of bearing layer is completely clear, replace the rolling elements, also cage being undertaken a comprehensive consolidation so that bearings can meet the performance requirements of a new bearing.
Once the deep groove ball bearings injure, they must go through a very rigorous testing procedures to determine whether the injury NTN bearings can be repaired. Bearings must be fully cleaned, and then a very rigorous and comprehensive testing. The first is to detect whether the bearing damage, such as cracks, spalling and thermal discoloration, bearing with these injuries are likely beyond repair and must be scrapped.
Raceway surface of deep groove ball bearings, due to contacting with the roller elements, its running track is the dark side, track attached to the roller surface is within the exception, which may be able to tell the load conditions, so in removing the NTN bearing cases, pay strict attention and observe of raceway surface running track, you will learn the it bears only radial load, subjected to an axial load, tolerance for moment loads, or extreme inequality of rigid on the bearing box.
1, appropriate clearance of NTN bearing, too large will impact, too small will be poor lubrication, may be burnt.
2, improve lubrication quality and control oil pressure, temperature and flow, strengthening the oil filter.
3, geometry and surface quality of NTN bearings and axle should be strictly guaranteed.
4, adopted the fuel and lubricating oil in accordance with the demarcation.
5, take control of engine temperature, overheating or in cold case work is negative. In cold weather, diesel engine should warm up before starting, scroll with the hand crankshaft oil into the friction surface.