AGMA 05FTM13-2005 pdf free download.Evaluation of the Scuffing Resistance of Isotropic Superfinished Precision Gears.
Sikorsky Aircraft Corporation performed Scuff ing Resistance Testing to obtain twenty four (24) data points for scuffing resistance, with gear testing being conducted at Pratt & Whitney Corporation in East Hartford, CT. The test plan was as follows:
1. Two spur gears (one gear pair) in a test rig were to generate two data points by utilizing both surfaces of the gear teeth.
2. Twelve data points were to be from baseline (final ground) test gear pairs.
3. Twelve data points were to be from isotropic superfinish test gear pairs.
4. All testing was to be performed at Pratt & Whitney Corporation in East Hartford using their 4-inch gear testing facility.
5. There was to be shared responsibility for writing the Manufacturing Methods Report.
However, after the gears had been fabricated, problems developed with the gear test stand at Pratt & Whitney Corporation, precluding its use. Consequently, Sikorsky Aircraft Corporation selected the Drivetrain Technology Center (DTC) – Applied Research Laboratory, at Pennsylvania State University, in State College, Pennsylvania to conduct the tests at their 4-inch gear testing facility.
Isotropic Superfinish
To perform the tests to the specified test plan, DTC requested a total of 17 gears of which 6 would be used for equipment set up, six were to be the baseline (final ground) (shipped directly from Sikorsky Aircraft Corporation) and five were to be final ground plus isotropic superfinish (ground samples were shipped from Sikorsky Aircraft Corporation to REM Chemicals, Inc. located in Brenham, TX).
It was determined by REM Chemicals, Inc. that the as received (final ground) gears were well within the specified maximum arithmetic mean roughness (Ra) of 20 mm. See figure 1 for profilometer measurement results for three of the baseline gears.
REM Chemicals. Inc. isotropic superfinished the contact surfaces of the five test gears with the goal of achieving an arithmetic mean roughness (Ra) of less than 3.0 mm. while maintaining a maximum stock removal of 0.00015 in. per surface. All five gears were processed as one batch in the same vibratory bowl. After isotropic superfinishing. the gears were measured once again to determine the final surface roughness. The values ranged from 1.9 mm. to 3.09 mm. Ra. See figure 2 for the protilometer measurement results for three of the isotropic superfinish gears. The witness coupon used to monitor stock removal indicated that a total of 0.0001 inch per surface was removed during the process. Based on the small amount of stock that was removed to achieve the required Ra, it was anticipated that there would be no detrimental affect to the gear geometry.
The five isotropic superfinish gears were forwarded to DTC, Upon receipt, DTC serialized the parts to establish identification for inspection and testing.AGMA 05FTM13 pdf download.