Sheet Metal Edge Bending

[TGINC]

I'm looking for suggestions on equipment needed to take a printed sheet of .009" sheet metal and bend the perimeter edge over 180 degrees onto the back for safe edges. This is a decorative consumer product that we are looking for even the terminology of what this type of bend is called and the equipment needed to produce. We're looking for a low volume bench tool for R&D, then when the product launches, we'd be looking for a piece of equipment needed to bend between 500-1000 of these in an 8 hour day. We will be producing 2 different sizes; letter size and tabloid size. Photos attached for detail of the front and back of a sample finished piece.

 

[Notarealsignguy]

Its called a hem.

 

[2B]

Automated sheet metal bending technology | WEMO

WEMO has several bending technology possibilities. Swivel-, roll, CNC-, variable radius bending, press braking and corner forming. Read more!

www.wemomachines.com

 

[Notarealsignguy]

For hems at a production pace you may want to look into HVAC duct fabrication and if nothing comes up to your liking general sheet metal production. A cheap gutter brake would do it but that's not going to work in large scale production

 

[TGINC]

For hems at a production pace you may want to look into HVAC duct fabrication and if nothing comes up to your liking general sheet metal production. A cheap gutter brake would do it but that's not going to work in large scale production

Thanks for that, I will check it out. The trick would be doing this without scratching the printed pieces...

 

[binki]

You will need a brake press. There are a number of them out there that will do the job. If you have something that is not very big, Harbor Freight has a hand held version.

 

[James Burke]

Former tool and die guy here....

Considering the material thickness and looking at the features and the finishes, I'd be willing to bet hard-earned money that this is being done with a very sophisticated (multi-action) die in a stamping press. Due to the bead and crimp, and the marr-free finish, it really is not feasible or practical any other way. The hem appears to be really tight, and that requires some initial forming operations of the bead before it is completely folded over and crimped. It's the crimping action against the beads that forces the edges down so tightly...which is not possible with a brake.

If you're just printing them, you may be better off finding a vendor for the blanks. If you plan to manufacture them, it could get pricey for the volume you mention.

JB

 

[TGINC]

Former tool and die guy here....

Considering the material thickness and looking at the features and the finishes, I'd be willing to bet hard-earned money that this is being done with a very sophisticated (multi-action) die in a stamping press. Due to the bead and crimp, and the marr-free finish, it really is not feasible or practical any other way (the hem requires some initial forming operations before it is completely folded over and crimped).

If you're just printing them, you may be better off finding a vendor for the blanks. If you plan to manufacture them, it could get pricey for the volume you mention.

JB

Good feedback - would the thickness of the metal give us some more clues? It's only .009" thick. Most of the videos I've seen of sheet metal hemming are with much thicker product, that does indeed need initial forming operations.

 

[Johnny Best]

I call that a reinforced edge.

 

[James Burke]

Good feedback - would the thickness of the metal give us some more clues? It's only .009" thick. Most of the videos I've seen of sheet metal hemming are with much thicker product, that does indeed need initial forming operations.

Yes. A simple hem that is only "folded over" 180 degrees will not produce the rigidity that is required of such thin material.

Being a consumer product (which appears to hang on the wall), weight, cost and safety means everything.

The beaded edges provide two main functions: they supply strength, and they provide finger-friendly edges that don't cut or snag.


JB

 

[Notarealsignguy]

This wouldn't be done on a press brake, if you were doing it manually it would likely be a box brake. I also think that this is some automated roll forming process. You can get a tight hem on a brake, metal trim panels are done this way. To produce cheap products like this it usually requires very expensive machinery that is designed for your specific need. Here is an example: https://www.estesdm.com/p4-panel-bender

 

[James Burke]

I call that a reinforced edge.

Indeed, it is.

The next time you crack open a can of Campbell's soup, take off the label and look very closely. The can itself is not much thicker than the OP's application. It's the corrugation along the middle two-thirds of the can that keeps it strong.

This application is EVERYWHERE...from automotive panels, metal roofing, beer and soda cans...you name it. Anytime you create a form or a bend in a flat sheet of anything, you introduce planes of rigidity that far exceed the mechanical properties of original stock.

Amazingly, the same principle allowed your very first paper airplane to fly.....and that's pretty cool stuff if you ask me.


JB

 

[Notarealsignguy]

Yes. A simple hem that is only "folded over" 180 degrees will not produce the rigidity that is required of such thin material.

Being a consumer product (which appears to hang on the wall), weight, cost and safety means everything.

The beaded edges provide two main functions: they supply strength, and they provide finger-friendly edges that don't cut or snag.


JB

That super thin material is also very difficult to work with using manual type equipment. It's like trying make something out of aluminum foil without getting any creases in it.

 

[James Burke]

That super thin material is also very difficult to work with using manual type equipment. It's like trying make something out of aluminum foil without getting any creases in it.

Exactly. But the very first clue I look for is the pristine finish on the front side. The edges are formed after the initial finish is applied to the metal.

There is absolutely no hint of (optical) distortion (ripples, creases, etc...) on the front surface whatsoever. That means the metal is firmly held within a die as the subsequent forming operations take place.

"Air bending", or die-assisted bending on a brake will never be able to produce this type of beautiful finish.


JB

 

[Notarealsignguy]

Exactly. But the very first clue I look for is the pristine finish on the front side. The edges are formed after the initial finish is applied to the metal.

There is absolutely no hint of (optical) distortion (ripples, creases, etc...) on the front surface whatsoever. That means the metal is firmly held within a die as the subsequent forming operations take place.

"Air bending", or die-assisted bending on a brake will never be able to produce this type of beautiful finish.


JB

roll forming would do the same which would make the most sense because you would run a straight line, coil to print to roll hem edges then shear. Or shear than form. That would keep it aligned through the process as well.

 

[signbrad]

Former tool and die guy here....

Considering the material thickness and looking at the features and the finishes, I'd be willing to bet hard-earned money that this is being done with a very sophisticated (multi-action) die in a stamping press. Due to the bead and crimp, and the marr-free finish, it really is not feasible or practical any other way. The hem appears to be really tight, and that requires some initial forming operations of the bead before it is completely folded over and crimped. It's the crimping action against the beads that forces the edges down so tightly...which is not possible with a brake.

If you're just printing them, you may be better off finding a vendor for the blanks. If you plan to manufacture them, it could get pricey for the volume you mention.

JB

A simple flat hem can be done with a brake. But a hem with a rounded bead like this is more of a problem for hand tools like a brake or rolling mill. I'm sure it can be done, but not easily or quickly. And making it stay flat and not warp will be a problem. Surely this was done with complex (expensive) equipment as James Burke said.

Some older cars in the 1930s had hems in the fenders like this. You can wrap the metal around a thick wire to re-create the bead.

Brad in Kansas City

 

[James Burke]

roll forming would do the same which would make the most sense because you would run a straight line, coil to print to roll hem edges then shear. Or shear than form. That would keep it aligned through the process as well.

Perhaps. But the two edges perpendicular to the feed direction would have to be done as secondary operations after shearing....which defeats the economy gained with roll forming, along with the potential for introducing un-balanced stresses during the process. Roll forming requires a lot more floor space.


JB

 

[Notarealsignguy]

Perhaps. But the two edges perpendicular to the feed direction would have to be done as secondary operations after shearing....which defeats the economy gained with roll forming, along with the potential for introducing un-balanced stresses during the process. Roll forming requires a lot more floor space.


JB

I looked at it on my phone and didn't notice that it wasnt a flat bend. You are probably correct with the stamping. Any way you look at it though, it's not going to be cheap to do.

 

[Johnny Best]

A trip to China and find a guy to make the die and then He will have his daughter form those out for you.
You have to tell her if she does not produce a #1,000 a day she will be sent off to force labor camp.

 

[James Burke]

A trip to China and find a guy to make the die and then He will have his daughter form those out for you.
You have to tell her if she does not produce a #1,000 a day she will be sent off to force labor camp.

Probably more true than we realize.


JB