AGMA 02FTM10-2002 pdf download.Comparison in Rating Trends in AGMA versus ISO.
Calculation Method
The comparisons made in this paper will be based on calculations made using the AGMA copyrighted ISO 6336 program and the newly developed AGMA program for calculations per ANSI/AGMA 2001. These two programs are being released as “Gear Rating Suite by AGMA”. Using these two programs to do the rating comparisons, the results are independent of any one individuals opinion or interpretation of either standard.
By using these programs, the input data for the gear geometry is the same for both the AGMA and the ISO ratings. This allows for a consistent trend analysis by only changing one gear geometry parameter while holding all of the other gear geometry items constant within the program.
The focus of this paper is to show the trends of the two rating systems by varying specific geometry parameters one at a time. This paper is not trying to establish a “rating constant between the two rating standards and should not be used as such.
Examples similar to the three examples from the 1981 AGMA papers will be re-examined to determine the rating trends with respect to changes in the profile shift. An example similar to the fourth example from the 1981 papers will also be reexamined to determine the rating trends with respect to changes in the helix angle. Two examples will be added to investigate the differences in rating trends with respect to pressure angle for a spur gear set and a helical gear set.
We will rate the gears as carburized and hardened gearing ground to AGMA Class 011. This is approximately ISO Class 6. We will assume that the material is per AGMA Grade 2 and ISO MQ. We will use the upper life factor curves and rate the gearing for a life of 10,000 hours. The pinion speed will be set at 1750 rpm. An input power of 250 hp (186.3 kW) is being used and the programs are being used to calculate the factors of safety.
In each example, the first calculated factor of safety becomes the reference factor of safety. The other calculated factors of safety are then divided by the reference factor of safety to get the Factor of Safety Trend value. In the tables, we are calling the Factor of Safety Trend “FST”. This is repeated for each rating item, pinion bending, gear bending, pinion durability, and gear durability. The Factor of Safety Trend is calculated independently for AGMA and ISO. The Factor of Safety Trend value is then plotted versus the factor being varied for each example.
How the Rating Programs Were Run
The tooling was specified as not having protuberance. The tooling tip was specified to be a full root radius or as large as the geometry would allow. Since the ISO ratings are made with tooth thicknesses that do not include backlash, the AGMA ratings were also made with zero backlash. No grind stock was specified. The surface finish was specified as 32 RMS for both the flank and the root fillet.AGMA 02FTM10 pdf download.