Need Help!- Help Bending And Making Metal Boxes

[Brenck]

Hi everyone...

I need to make a simple metal box, that i will be 16'' x 12'' x 7'' or 405 x 305 x 180 mm for thoose on metric...

It will be basically like a computer desktop, made by 2 parts, each of them with 3 faces on it, like wall-roof-wall and the other part rear wall-ground-front wall... The manufacturing of it its not the problem... But...

I need to make it from aluminium sheet, what i want it to know if is there any chart with the thickness of the sheet i need to use according to the dimensions of the box... I dont want to make it to think that will stay all loose and unstable and goofy and also i dont want to make it super thick that it will be heavy and more expansive due to the fact that im payng for all the extra weight on aluminium...

The box will only be to cover eletrical parts and it wont suffer any weight on to or sides or anything...

Thanks everyone

[rgarrett7]

I have never seen a table like you are describing. I think there would be a problem in creating something like that. The closest I can think of would be flex at a given length for a given weight. That is not going to be a straightforward answer to your question, though, because all the sides are supported. You probably need a college mechanical engineering text to get the equations to compute the correct answer.

Don't think you are looking to be that precise, so based on your description, I think .090 would be quite strong and not very heavy. You might be able to get by with .062, if the sides are well braced, but I think you might well see some bulging if there is any weight at all. I really don't think the sides would flex at all with .090

You also did not mention what alloy aluminum you were planning to use. If you use one of the high strength alloys, you should be fine (2024, 5052, 7075 -- almost certainly overkill). I'd be a little concerned about 3003, in terms of strength.

For the size box you are making, I don't think the thickness of the aluminum is going to make a significant difference in weight. You could figure it out, but it's probably a couple of ounces at most.

Don't forget, there is a minimum radius for each skin thickness and alloy. Too sharp a bend will break the metal immediately or create a fracture in the longer term.

Also, in addition to, or instead of, making bends, you could use angle aluminum for the edges and rivet the aluminum sheet to the angles. This would be stronger and would never fatigue. However, it would weigh more because of the angles.

Aircraft Spruce has information about aluminum in their online catalog. I have bought far too many things from them over the years.

Hope that helps.

[blackbeard52]

for something that small is there a reason you are choosing Aluminum? steel sheet stock will certainly be light and the physical properties are condusive to the sharp bends. using even a 29ga. steel will be strong and light if bent and fastened properly... the only reason I can find to not use steel is rust and if you use a galvanised surface even that can be reduced.

I guess I got off subject. But as Rgarret said the bends are a problem... easily broken on sharp radius. its why you see a lot of hardware on Aluminum cases.

Anyway here is the information you requested http://www.precisionsheetmetal.com/home/materials.htm

Bob

[PhoenixMetal]

If you go with regular steel, you will be fine with 24 gauge. We make enclosures of a size very similar to what you are describing and 24 gauge will be fine. For increased rigidity, you could use up to 16 gauge.

Originally Posted by Brenck Hi everyone... I need to make a simple metal box, that i will be 16'' x 12'' x 7'' or 405 x 305 x 180 mm for thoose on metric... It will be basically like a computer desktop, made by 2 parts, each of them with 3 faces on it, like wall-roof-wall and the other part rear wall-ground-front wall... The manufacturing of it its not the problem... But... I need to make it from aluminium sheet, what i want it to know if is there any chart with the thickness of the sheet i need to use according to the dimensions of the box... I dont want to make it to think that will stay all loose and unstable and goofy and also i dont want to make it super thick that it will be heavy and more expansive due to the fact that im payng for all the extra weight on aluminium... The box will only be to cover eletrical parts and it wont suffer any weight on to or sides or anything... Thanks everyone

[montifik]

Hello gentelmens,sorry for interrupting, can you answer me please, if i need to bend aluminium 7020 sheet(t=4 mm), do i have to heat it to 200 degrees of celsium?

[metalworkz]

Originally Posted by Brenck Hi everyone... I need to make a simple metal box, that i will be 16'' x 12'' x 7'' or 405 x 305 x 180 mm for thoose on metric... Thanks everyone

Hello,
The size box you want to make should work fine with 5052 H32 aluminum in .063" thickness. The .090" thick mentioned in a previous reply I feel would be overkill for what you are making. However you might want to take a look at alternative designs as far as to how you make the box. You will probably be able to use a smaller blank size for the 2 piece method you suggest but it may not work too well without some support flanges formed along 2 of the mating sides and perhaps a tab and keyed mating where the 2 halves are assembled. Also if this will be like a CNC control box with all the electronics inside you may want to include a door with hinges for easy access to the parts without taking the whole box apart.
You could even use thinner aluminum material(5052) if you provide some hat sections along the broad surfaces and good mounting flanges where each side fits with the other.