In order to assure reliability, the manufacture of gears for power tra
nsmission in high load bearing applications requires precise control o
f a wide range of processing parameters during manufacture, aimed at a
chieving specific material properties. Process selection and control i
n forming and heat treatment operations plays a crucial role in gear p
roduction, and must start at the design stage. Material selection, cho
ice of forming processes, thermochemical and heat treatment operations
, surface finish and condition will ultimately determine the integrity
and performance limits of the gears. An ongoing research programme by
Birrana Engineering, Adelaide, and the University of South Australia
involves the evaluation of materials, process route and process contro
l used in the manufacture of a range of gears and relates these factor
s to fatigue resistance, with the aim to reduce production costs and i
mprove gear quality and reliability. The results of single tooth bendi
ng fatigue, and contact fatigue tests on production gears manufactured
from EN39B steel (steel A), and experimental steels B, C and D (heat
treatment details restricted for commercial reasons) are presented and
discussed.