What is the typical thickness of the lubricant film under normal conditions?
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The shaft rotates inside sliding bearings and is lubricated with light oil. What is the thickness of the lubricating oil film between the shaft and the bearings under normal operating conditions? I’d like to ask; accuracy isn’t required – the order of magnitude is sufficient, please
It is actually very difficult to estimate the thickness of the lubricating oil film. Generally, the oil film in high-speed machinery is slightly thicker, while that in low-speed machinery is thinner. The thickness of the oil film is generally in the micrometer to sub-micrometer range; for some precision machinery, it can be even thinner, around a few layers of oil molecules thick, that is, in the nanometer range.
I once attended a lecture by a lubricant manufacturer, who said it was around 0.1 mm
At the micron level, the roughness is not high enough; how can lubrication occur in such a case?
This post was last edited by qugd on 2015-12-14 at 15:27. Roughness also comes in different levels, and the thickness of the oil film isn’t uniform either. In some machinery used for power transmission, the roughness can be higher, the allowable tolerances are greater, and the thickness of the oil film is also larger. For some high-speed mechanical components, the machining precision is very high; the oil film is thin. Such mechanisms are often sealed, require little lubricant, and do not oxidize during operation, as fluorinated oils are used as the base oil.