Din5480 is the din standard
for 30 degree involute splines.
You can use the Lewis equation to
calculate the loads after laying
out the profiles to get a close
approximation. It varies by
number of teeth and also by the
material strength that you are
using. Since the Lewis equation
is for tip loading and only one
tooth loading, you can multiply
the results by the number of teeth.
The trouble is the Lewis equation is for
inch sizes and the result is in pounds.
Basically the Lewis Equation is
W = sbY/Diametral Pitch
W = allowable tangential tooth load (pounds)
s = allowable stress (approximately 1/2 UTS)
b = face width inches
Y = form factor greater than .50 for 30 degree spline
Diametral Pitch = 25.4/Module
UTS = Ultimate Tensile Stress (PSI)
This should give you a rough estimate.
This is a best guess approach!
Lets assume you have a 5 module spline.
25.4 divided by 5 equals 5.08 diametral pitch.
I would think the addendum would be 40 percent
times the module ie. double stubbed form.
Stub gear is 80 percent times the module.
Assume the material UTS is 100,000psi
Spline interface b length is .75 inches.
Assume 24 teeth. (Y factor .5 guess)
Did not layout the teeth.
Then max load would be 24 times sbY/diametral pitch
24 times (.50 x 100000) times .75 times .5 / 5.08
equals 88583 pounds.
5 module with 24 teeth is 120mm pitch diameter
or 60mm radius or .19685 feet radius.
.19685 times 88583 yields 17438 ft-lbs (foot pounds)
torque or 23643 Newton Meters torque.
Will let you check the math!
The geometry of the spline profile per DIN is perfectly precalculated in that standard. Just pick what you need (dimensionally), select proper fit (standard, again) and calculate the length necessary to carry the torque.
Do not convert into inches - it is a metric spline.
gearguru
