I fell into a 4x12 sheet of aluminum.125 that is the same type as used for traffic signs. It doesn't want to bendin a brake without getting small cracks. How can i soften it to shape it or should I just use it flat? I'd l;ove to use it bit I'm stymied.
Aluminum can be annealed. Make your torch smoky and apply a layer of soot to the aluminum. Go to a neutral flame and heat till the soot disappears. This will bring most alloys to a dead soft condition.
Like he said, anneal the aluminum. You only need to do it where you are trying to change the shape. Does the sheet have any codes stenciled on it? Craig
Just use an acetylene torch, p*** over the sheet to get a layer of soot, go back and burn off the soot...
The soot acts as a sort of temp indicator, when it burns off your hot enough. Let the piece cool and your ready to go. I don't remember what the temp is. Craig
You can also apply some "Magic Marker" to it, heat it like you would with the acetylene soot and get the same effect. But you'll still need to watch the bend radius, even in the tempered condition. Like someone said above, any alloy and heat treat numbers that might be stenciled on the sheet would be helpful.
Not all aluminum alloys can be annealed...not sure which ones, but I don't think they can all be softened. Also, they need to be work-hardened again to stiffen up...if you anneal a piece of aluminum and bend it once, then leave it alone, it'll still be soft. I'm not sure if putting it in a brake will be enough to work-harden it. For the magic marker method, just run the torch over it until the ink burns off. That's roughly the same temp that the soot layer method reaches. The ink burning off is the indicator that it's ready. -Brad
rub some soap(outa ya bathroom like,the bar type)so it leaves a line.do this over area needing to be annealed.then heat the area until the soap goes dark brown/almost black.then quench with water to "lock in" the new annealed condition.i use this process before bending aluminium angle and channel into radiuses.
Your cracking issue is probably because you're trying to bend too tight of a radius. Usually, 3003 (I'm guessing this is what you have) need a min bend radius of one thickness. So for 0.125" you would need to be bending around the equivalent of a 1/4" rod. Most leaf brakes don't have a radius on them. A trick would be to bend a s**** piece around the upper leaf, then adjust your brake to clamp the bent piece, plus your workpiece, and bend your workpiece around the s****...this will increase your bend radius to the point where it shouldn't crack any more. Beware the "aircraft" aluminum alloys need larger bend radii yet, 6061 and 7075 both need a minimum of three thicknesses, or 3/8" in your case.
The street signs around here are made from 6061, structural stuff, pretty brittle but it can be annealed and formed. As you work it, it will work harden. You can continue to anneal it until the project is done if necessary.
Depends upon the alloy; all will work harden, some will air harden over time. Have to get my old metalurgy books out and study up on the rest...
Know this is an old thread but wanted to say you guys are a wealth of information and thanks for giving me what I needed to finish a project.
About 750 degrees F should do it. You will find that it is more prone to cracking when bent parallel to the long sheet axis. So if you just need a single bend, cut your piece so that can be bent across the grain. Also it helps to use a larger than usual bend radius. To accomplish this use another sheet of something more easily bendable say 3003, between the 6061 and the fingers of the brake.
Glad this popped up again. The 'secret' I recently learned, is to smoke the aluminum with the acetylene torch, them heat it from the other side until the soot goes away. works way better for me than letting the flame consume the soot.
Dead on the money. Just what I was thinking as I read this, street signs would probably be 6016, not what you want to use for forming. Depends somewhat on what you are making, if you just need to put a single fold in it, fine, but if you are planning on doing more forming,I would just get some 3013, and save the 6016 for a project where it was more appropriate. Trying to force a duck to be a goat is a waste of time and material.
I've had bad luck trying to anneal street signs, they always end up brittle as gl***! I gave up and quit stealing them!
Aluminum street signs are made out of a special alloy of aluminum that is very resistant to bending (think windstorms, hurricanes) and is also very resistant to weathering. I am thinking they may be made from age-hardening aluminum and actually gets "harder" over time.
I'll admit to a little secret. If you put my first car up on a hoist and looked at the underside of the trans tunnel, it said STOP.
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