Hello, can anybody tell me how much I can bend a 4mm dia 316 ss (or
304ss) rod in terms of bending radius? Is there a mathematical formula
that gives the maximum bending radius as a function of material
properties? Or where can I find the data for maximum bending radius for
rods made of different materials?
Missed the original post...just for the heck of it I tested on some
.225" dia (5.7 mm dia) material I had laying around...Material harder
than dead soft, probably a bit less than quarter hard.
"natural" bend radius (clamped in vice and just bent) was 7/16". Forced
radius without special tooling was 3/16". I know that we've often put a
true 90 degree inside bend on .307" (7.79 mm) dia T304 stainless rod and
haven't seen cracking. Of course, not seeing cracking doesn't mean it
wont show up under the right chemical conditions down the road.
Anyway, the point is, stainless is very ductile as long as you aren't
starting out pre-work hardened. Tight bends should be no problem with 4 mm.
Sure. But Grant's answer was just to good! :-)
If you can't find it in any table, here is a coarse way to calculate it:
You need the maximum elongation*) until the material breaks.
Then you pick some radius, calculate the length of the arc in the inner side
of the bend, calculate the length of the arc on the outer bend. If lengths
differ more than the elongation, it will break.
There will be other effects, so you will get an even smaller radius without
breaking. But I guess you come quite close.
With that I mean (don't know the technical term):
If you stress metal, it will get -after a certain force- longer (and _not_
spring back). That value is in % and in the ballpark of 5..20%. You have to
find it out for your material.
Ok... I was afraid of this. It's SO easy to explain with "chalk talk", I
forget how hard it is to describe without pictures.
Picture a gyroscope NOT as a disc rotating on a shaft, but as a SINGLE
particle in orbit around a point. Basically, you're looking at one atom of
the gyroscope's material. Every other atom will behave the same, so one
does the trick for the explaination.
View the rotation from one edge of the orbit, with the "axle" perspective
vertical through the center of the orbit.
For sake of the explaination, consider the orbit to be counter-clockwise --
Now allow the particle to orbit around until it's exactly in front of you --
between you and the "axle".
Summary so far -- vertical shaft, horizontal disk, rotation CCW, and we're
considering the point on the periphery of the disc closest to our view.
SNAPSHOT a velocity vector for the particle we're considering. It's moving
left to right along a straight horizontal line (if the gyroscope were of
Now apply a force upward on the particle in parallel to the axle, which
attempts to rotate the whole affair along an axis horizontal to your view.
What happens to the particle?
It was moving along a horizontal line. Now you've altered the vector to a
"lower-left to upper-right" direction. Nothing else changes.
Switch your mental view back to the single-particle gyroscope now. If the
orbit is now tilted lower-right to upper-left, then the whole disc of
particles will have tilted UP at a point 90-degrees in rotation from the
point of applied force to the disk.
Gyroscopic precession made simple.
What happens is you deflect it