A FEM study of the bending strength of circular fillet gear teeth compared to trochoidal fillets produced with enlarged cutter tip radius

Circular fillet (CF) gears have been proven to possess a higher bending strength than their standard trochoidal fillet (TF) counterparts. However, stronger nonstandard variants of the TF are already possible to produce by increasing the tip radius of the cutters used for gear generation (racks, hobs, pinion cutters), affording competitive results. In this paper a comparison of the bending strength is made between the CF and the nonstandard large tip radius TF designs spanning the entire usable tooth number range using FEA. The results suggest a systematic advantage of the CF over the stronger variants of the TF for numbers less than 17 teeth, which is the undercut limit for the 20 degrees involute gear system.