Recommended Shaft Surface Finish for Fatigue
Recommended Shaft Surface Finish for Fatigue
(OP)
Looked through a number of posts related to surface finish and fatigue life in shafts. I was unable to find the specific answer that I am after. Are there recommendations or suggestions for the surface finish to have on a shaft (transmitting up to 1200HP) to best function in fatigue? Are there any industry standards, studies, etc. that support a certain range? I apologize ahead of time if I missed a post that answered this.
Thank you,
Nate
Thank you,
Nate





RE: Recommended Shaft Surface Finish for Fatigue
RE: Recommended Shaft Surface Finish for Fatigue
http://www.asminternational.org/content/ASM/StoreF...
Ted
RE: Recommended Shaft Surface Finish for Fatigue
RE: Recommended Shaft Surface Finish for Fatigue
smooth is good, smoother is better, smoothest is best !?
unless of course you shotpeen the surface as a fatigue life improvement,
then cheapest surface finish is best (as the shotpeening will destroy it pretty well !).
but surface finish is pretty low down the (my) list of things to worry about as far as fatigue life is concerned. i'd start with cyclic stress, then material.
RE: Recommended Shaft Surface Finish for Fatigue
RE: Recommended Shaft Surface Finish for Fatigue
RE: Recommended Shaft Surface Finish for Fatigue
RE: Recommended Shaft Surface Finish for Fatigue
RE: Recommended Shaft Surface Finish for Fatigue
away from the bearing, why would you want more than stadrdard smooth finish, 32? 64 ??
but then i guess that's your question, what is the fatgiue benefit for increased surface finish.
i remember seeing somethng awhile back quantifying the fatigue life improvement with improved surface finish. i don't remember the details but thought it was an expensive way to increase fatigue life.
how close is your fatigue life to the goal ?
or is the question "how do i defend the smoothness i've selected ?"
RE: Recommended Shaft Surface Finish for Fatigue
http://www.eng.cam.ac.uk/DesignOffice/cad/proewild...
Ted
RE: Recommended Shaft Surface Finish for Fatigue
http://www.timken.com/en-us/Knowledge/engineers/ha...
As RB1957 said, how are the bearings, especially the bearing near the sheave/pulley mounted and secured to the shaft? Unless this is a fractional HP device, I hope not with commercial setscrew or eccentric collar. Their holding performance in the presence of rotating varying side loads like belts is poor, and they eat and etch the shaft right where the moment may be highest.
http://lejpt.academicdirect.org/A20/049_060_files/...
Also I'd do my cyphering using belt tension 3 or 4 times higher than than any prediction from the belt manufacturer.
Rather than machine tapered shafts, hubs and bushings, I'd try to used a commercial tapered locking hub ( ringfeder, etc) sleeve on an easy-to-make straight cylindrical shaft
RE: Recommended Shaft Surface Finish for Fatigue
That said, elimination of scratches that are transverse to the rotating axis (as in turning marks), the largest possible radii at the shaft steps, and shot peening all improve fatigue life.
David
RE: Recommended Shaft Surface Finish for Fatigue
Mfgenggear
RE: Recommended Shaft Surface Finish for Fatigue