I was at a student robotics competition and saw a team display that had some metallic panels that had been CNC routed to have a decorative pattern of holes in them. The team was using them as a sort of divider/lampshade. I asked them about the panels and was told that they were aluminum composite - they were maybe 1/4" thick, painted or anodized aluminum on both sides with a black plastic-looking core. I couldn’t touch them to get a sense of their mechanical properties. In looking these up, it seems like they are used most frequently as cladding panels for sleek modern buildings.
Has anyone worked with this material? Is the stuff strong enough to serve as a structural material on its own? How is it fastened to itself or its substrate? Some architectural applications show the panels following a curve; how is this done without creasing or kinking the skin of the panels? How would it compare, strengthwise, to plywood of the same thickness, or a plastic material like coroplast?
It looks like it would be a neat project material, but I suspect that you have to use mechanical fasteners like rivets or bolts to connect pieces together.
Quite a few client sites I have worked with recently have been specifying these materials. Hard to find a ‘modern’ look building without this somewhere involved - either as the primary facade material or a highlight or feature section. There is a huge range of manufacturers and types worldwide.
It comes as you’ve described - two thin sheets of aluminium sandwiching a core material. Core materials seem to be either plastic or a recycled mineral infill. I’ve seen sheets between 3mm and 9mm total thickness.
There is a huge range of fastening techniques based on the look you are after. They can be directly adhered using a glue, attached using a special double sided tape, screw fastened to framing, or have a hidden ‘cassette’ type framing system.
My experience with the material is that it is not a core part of the buildings structural integrity. It must be adhered to a suitable substrate or framing system. It would no doubt add some rigidity and strength to the structure once installed, but I am not sure if the structural designers factor that strength in. From a wind loading perspective it certainly forms a core part of the building envelope and this is a primary design consideration with the material - its wind resistance based on the different fastening methods available.
The core material has some flexure, so it can be rolled using similar machinery as to roll any other metal or plastic plate. To make sharp angles, the backing material can be locally removed so it doesn’t need to be compressed or displaced when folded. Aluminium itself is quite formable, so it is no surprise the ACP panels can be rolled, folded, bent, etc. I am sure each manufacturer supplies guidance as to maximum rolling angles and how much radius can be achieved per pass through the rollers to prevent creasing etc.
A brief comparison between a couple ACP products and plywood shows me that the tensile strength, bending strength and rigidity of ACP products significantly outperforms a standard range of structural plywoods in like for like thicknesses. However there is such variance in plywoods that no doubt there are plywoods available with similar properties.
It has been subject of some controversey over the last few years due to poor fire performance, resulting in some epic multi-storey building fires all over the world. So take care what the manufacturer states with respect to fire resistance - if it involves a significantly plastic core, it probably burns with an intensity that would outstrip plywood by significant level.
Check out some (australian) information available here
Thanks for the information, Richox. The link to the fastening systems were particularly helpful.
I was mostly interested in evaluating this as a weatherproof/rotproof replacement for thin plywood sheets for outdoor projects - like the sheathing of a teardrop trailer, or outdoor furniture or storage. It looks like that might be feasible with rivets and/or adhesives to do the fastening.
Pretty much all of the examples of this stuff in use that I can find are building cladding projects, though, so I was wondering if there was some other issue with the material besides, perhaps, cost. For example, maybe the aluminum skins are designed to hold up against wind and rain but they won’t tolerate being sat on or rubbed against the dirt…
You can get a variety of aluminum honeycomb panelswithout a plastic core; filling the sandwich is aluminium and air. These typically weigh more than plywood, but are a lot stronger and some are specifically advertised as resistant to weather, corrosion, and dirt/debris.
Such panels are easy to cut to size and fasten and/or glue together.
Aluminum composite panels are used extensively in construction of airplanes & helicopters. If you’ve been in a commercial airliner, you’ve almost certainly walked on aluminum composite panels used as cabin floors.
As a “for example”, the cargo floor of the USAF KC-10 (and the civilian DC-10-30CF) is constructed of a .016" aluminum sheet on top, a 1/4" balsa wood core, and a .010" aluminum sheet on the bottom, bonded together into panels that are fastened with screws to the aircraft’s floor beams. I forget the PSF rating of the KC-10 floor, so I can’t give a specific number on that. I do recall a caution in the operating manual (the “Dash 1”) about female passengers wearing high-heeled shoes and other point-type loads.
One potential drawback of composite panels of any construction is water ingress, especially in climates with freezing temps. Water degrades/corrodes some core materials, and freeze/thaw cycles will obviously cause debonds between skins and cores. A great deal of the strength of composite panels is the bond between skin and core; debonding and delamination will quickly destroy the panel’s structural integrity.