Request for Interpretation for ANSI/AGMA 9005-F16, Industrial Gear Lubrication
Issued March 21, 2023
Question / statement:
ANSI/AGMA 9005-F16 Annex B, seems to suggest that the choice of viscosity grade for spur and helical gears is dependent on the operating temperature, pitch line velocity and viscosity index. So that, for example, at an operating temperature of 50 degrees Celsius and a pitch line velocity of 5 m/s, the tables in Annex B suggest mineral oil with a viscosity index of 90 and a viscosity grade of 150 and synthetic oil PAO with viscosity grade of 100 and synthetic oil PAG with viscosity grade of 100, that is by choosing synthetic oil, the viscosity grade should be lower.
But, according to my last study and research and the coding that I did based on the AGMA 925-A03 standard in MATLAB software, I came to the conclusion that for temperatures below 60 degrees Celsius , mineral base oil has a stronger oil film thickness than the PAG and PAO synthetic base oil, and we should not choose a higher viscosity grade of mineral base oil in this temperature range.
So, I conclude that the tables attached in ANSI/ AGMA 9005-F16 Annex B definitely need to be revised and the thickness of the oil film should be taken into account.
AGMA Lubrication committee response:
The committee feels that the first sentence of B.1, “In the absence of gearbox manufacturer recommendations, specific application standards, or a rigorous EHL analysis, the following tables are offered for the user to select an appropriate viscosity grade for their application” clearly states that the tables are to be used only when no other information or recommendation is available. With that said, the committee agrees with Mr. Beyralvand’s proposal and plans to review the tables, and update them as needed, during next revision of AGMA 9005.