Material for driveshaft
Material for driveshaft
(OP)
I made a center driveshaft for an off road race car from 1" 1018 steel. The shaft failed by twisting through about 30 degrees and bending slightly. I am trying to figure out what material to upgrade to. I have room to go as large as a 1 3/8 inch dia. shaft and can find 1215 grd. splined shafting and hubs (5 spline or 22 slpine) locally. I am not familiar with the metalurgy ... would the 1 3/8 inch dia. 1215 shaft provide signnificantly more strength that the 1 inch dia. 1018? Any other suggestions for matl and where I might get splined shafting?





RE: Material for driveshaft
Are you buying hardened and ground stock?
I would think you would want a 1040, 4140,
4130, ie a higher carbon content in the material
selection for a shaft.
RE: Material for driveshaft
Neither 1018 nor 1215 have the high strength necessary for a demanding application such as a driveshaft. Heat treatable, meaning quenched and tempered, grades like 4130 and 4140 are suitable, and frequently used for smaller quantities like yours. Without knowing the forces/stresses involved, I would estimate that heat treating to a hardness of 35-38 HRC would be a good place to start.
RE: Material for driveshaft
As diamondjim says I would reccommend going with an alloy steel like 41xx or 43xx.
I dont have hardenability data on these steels handy, but for normalized bar you will see strengths of over 90ksi. The 43xx will have higer hardness through the thickness, whereas at ~1" the 41xx alloys will have a tough ductile core with a hard case.
You might also want to try thick walled alloy tubing, if you can get the diameter larger you will have more stiffness and wont suffer a huge weight penalty.
As far as getting splined shaft I have no idea. You could likely find a machine shop in your area that will be able to machine raw bar.
Nick
I love materials science!
RE: Material for driveshaft
Mark
RE: Material for driveshaft
RE: Material for driveshaft
http://www.seshafting.com/index.html
You might want to check with these people also.
www.gorbinc.com
RE: Material for driveshaft
I have used Hex shaped shafts before with good success.
As Rowyco states, the 1/4" key give less surface area for toque transfer.
The splined shaft will center itself in the joint, while the keyed shaft may do some other things.
Some more information might help: are there u-joints at each end, is there a lot of movement (shaft sliding in one yoke), how long is the shaft?
RE: Material for driveshaft
RE: Material for driveshaft
2 use axle steel to make axles
Increasing the OD will help, obviously, but axle steel is good stuff.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Material for driveshaft
should be a great improvement that
unclesyd's site referenced.
This seems like a cheap alternative.
Larger diameter is always better as
the area increases by the square of
the diameter. The 1 3/8 diameter would
give you 89 percent stronger shaft.
A 1 1/4 diameter would be 56 percent
increase is in area. A 1 1/8 diameter
would give you a 26 percent increase.
You mentioned a 30 degree bend. Is the
load overhanging or offset?
RE: Material for driveshaft
Sounds like you're trying to keep cost to a minimum. I agree with the others that a heat treated alloy steel is the preferred solution. It is certainly possible to buy heat treated 4140 round bar stock and have a gear shop machine splines into it, though this would certainly be more costly than off-the-shelf splined shafting.
That being said, going from 1" 1018 to 1-3/8" 1215 is a very large improvement.
1215 is designed for easy machining - not for fatigue strength. Though it's yield strength is similar to that of 1018, it's fatigue performance will not be as good because of the sulfur and phosphorous which are added to make machining easier.
Other things being equal, strength increases as the cube of the diameter - you would be multiplying your strength by about 2.6. Even though you'll suffer a slight loss due to lower fatigue performance, you'll be way ahead with the size increase.
RE: Material for driveshaft
RE: Material for driveshaft
A spline is even more detrimental to the strength since you are removing more material. If you need to spline or key the shaft, do so at the ends ONLY....this will also save you a lot of machining.