I would like some instructions for setting the degrees and minutes on a Liebherr
or Barber Colman hob. Our machines use a Vernier scale to match the lead angle
of the cutter to the part to form straight teeth. There is a dispute on how to do
this task, and I wanted insight from another professional.
Cracks initiated at the surface of case-hardened gears may lead to typical life-limiting fatigue failure
modes such as pitting and tooth root breakage. Furthermore, the contact load on the flank surface
induces stresses in greater material depth that may lead to crack initiation below the surface if the
local material strength is exceeded. Over time the sub-surface crack propagation may lead to gear
failure referred to as “tooth flank fracture” (also referred to as “tooth flank breakage”). This paper explains the mechanism of this subsurface fatigue failure mode and its decisive influence factors, and presents an overview of a newly developed calculation model.