Hard vs. tempered involute spline 1

[spigor]

Does it help in anything when the mating surfaces of an involute spline are hard (e.g. carbourized)? They just touch, no friction, so maybe tempered is equally good?

 

[CoryPad]

Splined components must withstand shear stress, contact stress, wear, and fretting fatigue. Hard surfaces generally are better for these applications.

 

[tbuelna]

spigor,

If the spine teeth need to have a long fatigue life, then case hardening is helpful if the simple contact stresses (P/A) are above about 5ksi with most alloy steels. As CoryPad points out, fretting is generally the biggest concern with regards to long life splines.

Be careful with carburizing or nitriding spline teeth. If the teeth are fine pitch and of small cross section, you can easily through harden the teeth, making them brittle and prone to fracture. So watch your case depth, break edges, and mask carefully.

Good luck.
Terry