EVALUATION OF HIGH ENERGY RATE FORGED GEARS WITH INTEGRAL TEETH
Final rept. Jul 1965-Sep 1966
WESTERN GEAR CORP LYNWOOD CA RESEARCH DEPT
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The fatigue properties of gears forged with integral teeth were compared with those of gears machined from bar stock and gears machined from simple upset forgings. The gears tested were manufactured from both air melt and vacuum-melt 9310 steel and tested on a single tooth fatigue testing machine at 175,000 and 157,000 psi Lewis bending stress. At both stress levels the gears forged with integral teeth had average fatigue lives approximately seven times that of the machined gears. More scatter was experienced in the fatigue data of the forged gears over that of the machined gears. However, statistical analysis by the Students t method shows that the low mean fatigue life of forged gears was twice as high as the high mean fatigue life of cut gears. Several metallurgical processing variables including case depth, surface hardness, grain size, and static strength were examined. No correlation between these parameters and the scatter in the fatigue data of the forged gears was found. Neutron activation analysis was used to determine the relative wear of the four types of gears studied. Very little difference between the wear properties of the various gears investigated was observed, indicating that forging gears with integral teeth or machining gears from upset forgings does not change the wear properties over that of conventional gears machined from bar stock.
- Properties of Metals and Alloys
- Machinery and Tools