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Purpose for Chamfer on Edge of Spur Gear Teeth?
- Thread starter badpeanut
- Start date
mfgenggear
Aerospace
one answer is
depending on the type of material & heat treat process, case hardening such as ion /or gas nitride, vacuum or endo gas carburize.
it prevents gear teeth from chipping.
having chipped teeth is very bad.
easier engagement of gear teeth
depending on the type of material & heat treat process, case hardening such as ion /or gas nitride, vacuum or endo gas carburize.
it prevents gear teeth from chipping.
having chipped teeth is very bad.
easier engagement of gear teeth
MikeHalloran
Mechanical
When the shafts become misaligned, e.g. while deflecting under load, that general area will be particularly stressed, and relatively likely to fail in fatigue, throwing a chip that will eventually find its way into the mesh and destroy the gears. Better to remove it preemptively.
Still better; cut a small chamfer over the entire end profile, which is laborious and expensive when done by hand, but I think some machinery exists for the purpose.
NOT better; abrasive flap wheels and related items. The random scratches from the abrasive grains don't help fatigue life.
Mike Halloran
Pembroke Pines, FL, USA
Still better; cut a small chamfer over the entire end profile, which is laborious and expensive when done by hand, but I think some machinery exists for the purpose.
NOT better; abrasive flap wheels and related items. The random scratches from the abrasive grains don't help fatigue life.
Mike Halloran
Pembroke Pines, FL, USA
mfgenggear
Aerospace
an other answer is
to prevent cracks from propagating
from sharp edges!!!
to prevent cracks from propagating
from sharp edges!!!
badpeanut,
Gear tooth chamfers and corner breaks are very critical on case hardened, high performance gears. As others noted, the primary function is to prevent through hardening of those sharp edges during carburize/nitride. The hard brittle corners would fracture and break off during operation of the gear. The amount of chamfer or edge radius depends upon the case depth.
As for why a chamfer is used, the chamfer is usually easier to machine than a corner radius. But a radius would work just as well.
Because tooth edge breaks can be so critical, there is specialized machinery to produce very precise gear tooth edge breaks:
Like most things with regards to high performance gear design, it's all about the details.
Good luck.
Terry
Gear tooth chamfers and corner breaks are very critical on case hardened, high performance gears. As others noted, the primary function is to prevent through hardening of those sharp edges during carburize/nitride. The hard brittle corners would fracture and break off during operation of the gear. The amount of chamfer or edge radius depends upon the case depth.
As for why a chamfer is used, the chamfer is usually easier to machine than a corner radius. But a radius would work just as well.
Because tooth edge breaks can be so critical, there is specialized machinery to produce very precise gear tooth edge breaks:
Like most things with regards to high performance gear design, it's all about the details.
Good luck.
Terry
- Thread starter
- #7
Thanks for the input everyone!
These gears are through hardened 4340 steel, or through hardened 440C stainless depending upon where they are located. The final stage is shot peened.
Any guidelines as to the chamfer size (minimal, down to the pitch diameter, down to the root diameter, larger than the root diameter, etc.)?
These gears are through hardened 4340 steel, or through hardened 440C stainless depending upon where they are located. The final stage is shot peened.
Any guidelines as to the chamfer size (minimal, down to the pitch diameter, down to the root diameter, larger than the root diameter, etc.)?
dinjin
Mechanical
- Jun 15, 2008
- 336
- 0
- 0
It also helps in handling these parts if you do not have sharp corners on the outside diameters. We used a rough
approximation of 1/4 times the module for the chamfers.
When the pinions are over hung, often a very large chamfer
was initiated at that leading edge equivalent to 1.2 times the module or greater.
approximation of 1/4 times the module for the chamfers.
When the pinions are over hung, often a very large chamfer
was initiated at that leading edge equivalent to 1.2 times the module or greater.
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- #11
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