First, understand the operating conditions of the aircraft engine:
1. High speed, the general aircraft engine speed is above 18,000 rpm, such a high speed has high requirements for materials.
2. High temperature, the operating temperature of the engine is very high, and the operating temperature of the bearing may reach 300°C. The bearing material needs to be able to withstand high temperature.
3. High reliability, whether it is a civilian aircraft or a fighter jet, the requirements for reliability are very high, and a slight difference can be life-threatening.
Once you know the operating conditions of the bearing, you can choose a bearing suitable for this working condition. Since the operating temperature of the bearing is very high, the outer ring is made of AISI M50 material with high temperature resistance and high temperature stability. This material has a hardness of 300°C It can still reach 58HRC.
When running at high speed, since the inner ring of the bearing is rotating, the centrifugal force is very large, and the section of the inner ring of the bearing bears the circumferential tensile stress, so there should be no microscopic cracks on the surface of the inner ring to avoid crack expansion under the tensile stress, so it is often used The inner ring is made of AISI M50NiL material.
Due to the very high speed, in order to reduce the additional load of the steel ball due to centrifugal force, generally use a relatively light weight, relatively high hardness ceramic material, such as silicon nitride (Si3N4) or titanium carbide (TiC) as the steel ball material , Sometimes in order to increase the wear resistance of the inner and outer rings of the bearing and reduce friction, the inner and outer ring raceways are also sprayed with ceramics.
There are so many pipelines, part of which is used for lubrication. The lubrication of engine bearings is actually similar to the lubrication of ordinary bearings. Because the bearing speed is too high, contact seals cannot be used, so the engine bearings use labyrinth seals, but the lubricating oil he uses is better. Many, because the operating temperature is too high, the general lubricating oil is easy to oxidize and deteriorate, so the synthetic oil MIL-PRF23699HTS is generally used.
