Fastening to Perforated Sheet Metal

[rhwiet]

I have a layered, vertical panel as follows: solid 18ga steel, 2" fiberglass insulation, perforated 22ga steel with 25% open area.

I would like to fasten load-bearing parts to the perforated side of this panel, but am an unsure on how to determine the number of fasteners needed? Is this even do-able? Thanks in advance!

 

[Jboggs]

One does not often hear the terms "load-bearing" and "perforated" in the same context. In my mind, that's a good recipe for a bad reputation. Whenever the phrase "Who's the guy that came up with this?" runs through my mind, I find another way.

Your load can be positioned over the perforated sheet but the supports should span to some stronger members, like the surrounding framework.

 

[rhwiet]

Ok. What if I wanted to fasten to a solid sheet metal face instead of perforated? I am new to most aspects of sheet metal design...

 

[drawoh]

rhwiet,

Perforations do not scare me. You can account for it in your calculations. Work out your weight saving. It will not be impressive.

An overall sheet metal structure can be very strong and rigid if you design it carefully. Your biggest problem is attaching stuff. A secondary problem, if you are used to machined parts, is that sheet metal is less accurate. You need to think through your drawings carefully.

Plan on doubling and tripling your sheet metal layers at connection points. For aluminium sheet, PEM nuts and their equivalents make strong tapped holes. Screws and regular nuts will allow sloppier holes.

--
JHG

 

[MintJulep]

Where does the load go next after the perforated sheet?

That is to ask, what is the perforated sheet attached to, and how is it attached to it?

If the answer is that the perforated sheet is attached to the fibreglass by glue and wishful thinking then you need to rethink your plan.

 

[dhengr]

Rhwiet:
As mentioned above, you really have to define your problem better. Is the fiberglass 2" of batt insul. or is it some form of rigid foam insul., and bonded to the two outer sheets? How are the two outer sheets fastened together, and then to some support structure? What are the loads, a couple 10lb. loads would be treated differently than 500lbs. What are the perforation holes, size, shape, etc? Can you screw (sheet metal screws) load supporting brackets right into the existing holes (light loads), or do you have to back-up and reinforce the perforations for good support? I’m always amazed at how much important info. you guys leave out of your OP’s and expect some sort of a magic, all encompassing, answer. E-Tips has become the game of 20 questions, for all to play, rather than a meaningful exchange of info. and ideas btwn. real engineers. We can’t see it from here, so you gotta clue us in.

 

[Tmoose]

The perforated sheet sounds like it might be an acoustic feature, if the fiberglas is batt.

http://image.shutterstock.com/displ...tock-vector-speaker-grill-vector-62769034.jpg

 

[berkshire]

If you are fabricating these panels ,you could add a narrow strip of solid sheet metal behind the perforations to carry your fasteners.
That way you do not have to worry about breaking out the edge of your perforations, when you punch or drill for your fasteners.
B.E.

You are judged not by what you know, but by what you can do.

 

[rhwiet]

MintJulep - The perforated sheet is attached to the solid sheet using fasteners (see the attached image).
dhengr - I didn't mean to come across as if I was expecting the forum to do all of the work for me. I am just trying to get some experienced opinions about the problem at hand.

Maximum weight we should see is about 500 lbs. Insulation is fiberglass batt.

Thanks for all of the suggestions and responses!

 

[MintJulep]

500 pounds is non-trivial and 22 Ga is rather thin.

Stiffness (or the lack of it) will be a significant challenge.

How large are the panels? What is the loading direction? Where is the load relative to the plane of the perforated sheet?

 

[berkshire]

Is it possible to remove the perforated panel, then attach brackets to the 18ga box , replacing the perf before attaching your load, and screw through there into the brackets?
B.E.

You are judged not by what you know, but by what you can do.