Maximum temperature of ISO VG32,46&68 oils for sufficient film thickness between meshing gears?

[SMKRe]

The ISO VG 32,46 and 68 oils are being used in gearboxes.
The gearboxes here specifying are high speed and high power gearboxes.

what is the maximum operating temperature of ISO VG 32 , 46 and 68 oils to have required viscosity to form sufficient film thickness between the meshing gears? if the gears are having surface roughness of 0.5 microns.

 

[geesaman.d]

You have two questions here:
1) What is the required viscosity of oil to maintain EHD of high speed gearset with roughness 0.5 microns
2) What is the temperature vs. viscosity curve of ISO VG 32, 46, 68 oils, such that I know the maximum operating temperature that any of these oils can be used in my application? That should come from the lubricant viscosity curves.

What methods are you currently using for EHD film thickness calculation? A quick google search provided a lot of content.

https://www.geartechnology.com/arti...specific-film-thickness-and-gear-pitting-life