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Thread: forming honeycomb panels
09-08-2005, 11:43 AM #1
I am working on a design for a client where we are considering using honey comb panels. 1/4 paper honeycomb with .040 al on one side perhaps .020 on other. the idea is to get rigidity both stiffness and torque resistance. This is an exterior container application. Question is, how do you form this? can you simply brake form it. ie crushing the honey comb core? how would you form a rounded corner?
09-08-2005, 12:15 PM #2
Not sure what you are doing, but my company used to buy the honeycomb and aluminum separately, form one piece of aluminum over a mandrel, apply glue and honeycomb, then vacuum bag. Apply second sheet of aluminum with glue and vacuum bag again.
09-08-2005, 01:00 PM #3
Ask Hexcel- even their name means honeycomb. They make and fabricate the stuff, in all kinds of wack materials. They have a plant near me, and we hit the dumpster from time to time, getting stainless, aluminum, and phenolic honecomb.
09-08-2005, 01:13 PM #4
09-08-2005, 03:19 PM #5
I was hoping to be able to buy prelaminated sheets and brake form it advoiding the labor of glue up.
09-08-2005, 03:39 PM #6
Hexcell is more into the honeycomb not finished panels Try M C Gill Composites. They make stock panels
09-08-2005, 03:44 PM #7
"I was hoping to be able to buy prelaminated sheets and brake form it advoiding the labor of glue up." Is appearance any concern? Unless you had some sort of very wide roll-form dies, I would think prelaminated homeycomb would crush at the male and female dies long before it starts to bend.
09-08-2005, 05:16 PM #8
I was thinking that a double 45 could be formed with 2 parrallel crush bends, keeping the crush onthe inside of the bend, the exterior has to look nice, the interior can be 2 nd class.
Right now they are welding an aluminum box section for stiffness, this is costly and interfers with the anodized finish on the exterior.
09-08-2005, 05:34 PM #9
If you bend the honeycomb, you have just created a weak spot. They usually put 2 sheets together with stiffeners that are bonded mechanically to the flat sheets. The open edges of the panels are also filled.
If you're in aircraft, they fill the honeycomb with wax and then mill it to the shape they want, then remove the wax. The skins get an adhesive coating and everything is assembled in a fixture. The fixture is put in an autoclave and either vacuum applied to the fixture, or pressure applied to the outside, or both.
In one of my other lives, I worked for a place that made F-4 tail sections and the back half of the "saucer" on the AWACS planes. Boy, that goes back 30 years!
09-09-2005, 12:01 AM #10
If it were up to me and ultimate strength wasn't the issue, I'd bend up some thin sheet angles like I wanted and rivet, bolt, or bond them to the honeycomb sheet to make corners, one inside and one outside.
If you try to bend it, it'll probably tear the outside.
09-09-2005, 03:19 AM #11
It occures to me that this question is more of an engineering question than a fabrication one. What kind of strength are you hoping to have in these crush bends? If you are expecting much at all, I would think again. If the bends do not need to be strong, but simply hold the walls in place, then I wouldn't worry about it so much. For example, if you were trying to make a cube out of this stuff, the edging might not matter thatn much intermes of strength and rigidity and your technique might be fine. But if you are trying to make a shovel, you are going to be very disapointed.
In short, ask the engineer... or barring that, run a test.... or barring that form the pieces and glue up seperatly.
really it is all to do with the loading that you will expect.
09-09-2005, 09:21 AM #12
THe idea of using honeycomb is to cut down ont he twisting of a large 20 x 60 sheet metal lid. A pan is now welded to the inside, but that is expensive to do and interfers with teh anodized finish. I am examining several ideas to stiffen the lid and have lots of options. I have worked with flat honeycomb many years ago. that had carbon skins over nomex core, ironically it had to be perfectly opaque, but we found out the carbon was so thin that it was translucent, who would had thought? Anyways that stuff was very expensive, this project calls for paper honey comb approach, or perhaps a foam core.
09-09-2005, 01:36 PM #13
How about cutting a 90 degree notch at the inside location of the corner, then bend?
09-09-2005, 01:40 PM #14
GMTA George hehe, I was gonna go there but you beat me to it, the inside corners could then be re-inforced with a brake bent 90 glued or otherwise fastened to the aluminum inner skin.