Sheet Metal - Embossing

As a very simple explanation.

The strength of a simple cantilever is proportional to the cube of it's thickness.

Any embossing or return effectively increases the thickess in that area (or along the line of a bend) and therefore vastly increases the strength along the bend...

By having a shaped embossed area rather than a simple bend the increased strength can be extended over the whole area rather than just being localised along one plane as would happen with a simple straight line bend along one edge of a sheet.

Friend, r u tryin to relate moment of inertia with the strength ?

i.e. moment of inertia of a rectangle is [ bxdxdxd/12 ] if b is considered as base & d is thickness & it gives different results if the same is rotated by 90 degree.

!!!??

Nope... I say what I mean

..I mean what I say.

do you have any technical document abaout sheet metal embossing? can you sent it to me? my email adress:glr.hande@gmail.com

I am not a sheet metal mechanic.

Is there a language or terminology variation that I am not aware of. Is this a tradesman's term.

I am thinking 'flange-ing' but can only associate embossing with a stamping or appearance based effect as opposed to a strengthening process.

cr3

Yeh, I'm not sure I'd call it embossing...dunno if there is a better term.

But you know the stuff, ridge or groove (often semi-circular cross) section say 5mm deep pressed in for strength/stiffness. Just think auto floor pan?

Re. next reply...I find imaginary forces generally don't do much .

'Yeh, I'm not sure I'd call it embossing...dunno if there is a better term.'

Beading? I've beaded (embossed?) long runs of stainless panel using a bespoke tool in a punch press. Mind you, no calcs required, it was all cosmetic.

If I'm following you it would be similar to knurling a handle, only flat like a running board on the truck ?

Does this make sense?

A picture is worth a thousand words.

In my case 6.7 words.

I always thought that was to align mating parts and help with draining.

Take a across section of plain sheet & embossed sheet apply imaginary force, you will get the answer.

Two basic mechanisms that I can think of: work hardening and increasing structural depth.

The most effective of the two is the latter whereby creating say a dome in the plate will effectively increase the overall strucural depth of the section. The dome acts by arching from one side to the other and thrusts out on its perimeter. The perimeter acts as a hoop in tension; at the base of the dome this is a simple task for most materials (concrete or brick domes have steel perimeters like at St Paul's Cathedral).

However, patterning of embossed sheets can still leave an overall weak section such that you can find a line of least resistance created in between the bosses. If you want to strengthen the overall shape with small patterned bosses, an overall check is also required. The edge conditions can be quite critical.

The work hardening is a material property whereby stretching the metal at low temperatures increases its yield strength. This is especially true of stainless steels where the strength can attain 1000MPa for drawn rods. Their ductility is reduced and any heat subsequent heat treatment will generally bring the yield point back down to its original value. Welding can therefore be a problem.

For most sheet metal purposes, it is the new geometry that is the key.

Wow! I've been working sheet metal for more than 12 years, and NOW I know that there is a science behind these designs. Thanks! (Well, I always suspected....) I guess there is so much cosmetology involved that often the engineering becomes invisible. A car door "could" be made from corrugated metal, like barn roof, but it looks better to have a long slow curve.

Generally speaking, rolled edges (like around fender wells) provide stiffness. In the case of medieval body armour (which is my area of expertise, no really!), rolled edges are there for safety. Ridges are known as flutes...and they provide a fair amount of stiffness. Some armours in museums are heavily fluted. They normally show few signs of ever being used. They are not as popular as you might think because it is much more expensive to repair a dent in a fluted surface than in a flat surface. And of course fluting is an expensive process to do in the first place! The fluting stresses the metal, making it more likely to crack along the bead, and more importantly, wear is now concentrated on a narrow ridge.

Now you got me interested in the science behind my trade again! I think I will reread Gordon's book "The New Science of Strong Materials" , I think there was some of this info in there. Again, thank You!

you asked me "do you have any technical document about sheet metal embossing?" Oh man, what a question!

I imagine googling "panel-bashers" or "body work" would do the trick. It is interesting looking at the way aircraft, esp. high performance aircraft like space capsules are built....they use the minimum material in order to do a difficult and complex job. For instance, the wing of a large aircraft. There is the outer surface which forms the airfoil, the supporting corrugated inner surface which often carries hot air from the engines for de-icing and wiring for fuel sensors, and the ribs which hold it all together. The gauge and type of metal is dependant upon factors such as how big the wing is, how much fuel is being carried in the wing, the expected loading, and the airfoil shape which provides lift. This is not a field one walks into cold! Maybe with a few books in hand! Carleton University demands a 3 year "core" engineering program before going into this field of study...then it is two years after that before you can even think about getting an entry level position in Canadaire. So my recommended reading list would pretty much be "aisle three and half of aisle four of the University text book room.

Get an english wheel, a planishing hammer, a sand bag, and a few sheets of steel, make fancy fenders for motorcycles....a lot less studying, and you get to see something for your work. Find one of the "old guys", buy him a couple of packs of cigarettes, and get him to show you how it is done. Then you will be able to narrow down the questions to only half the engineering library!

Ahhhh.