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Fixing channel to acm panel, recommendations on fixing?
Can any of you lovely people recommend a suitable fixing for attaching sign channel to Alu composite panel, seems that many are using flush rivets but struggling to find any suppliers?
Any help greatly appreciated!
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20 Replies
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VHB tape & rivets are what I generally use, try searching for countersunk rivets, lots of suppliers but don’t have any names on this machine.
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we use countersunk rivets, and tape from http://www.indasol.co.uk/ we tried 2 pack adhesive, didnt work to well
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Cheers Martin/Gary have managed to find some now searching for countersunk instead of flush 🙂
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just my take on it, but i wouldn’t use countersunk on composite.
composite aluminium skin is thin enough without then removing more aluminium on one side to sink/hide the fixing.
also, some composites depending on brand and type have a thinner skin again!i have used tons of quality branded composites from dibond, rynabond and the like with channel rail fixings riveted to the rear.
in several instances over a period of about a year, we saw the face being tore from the rails in high wind. basically the rivets were left on the rails, the composite was too soft and the rivets were pulled through the face. granted these were in very remote high wind exposed areas but still… we reverted to using aluminium and it solved the problem.
Nowadays when using a composite on channel rails for any reason we couple up the area thats been riveted with a 3-4 inch strip of general use VHB tape. this spreading the load preventing rivets being pulled thru the face.i know this may sound extreme, but its more a belt and braces exercise if we need to use composite over aluminium. once bitten and all that! 😉
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quote Robert Lambie:just my take on it, but i wouldn’t use countersunk on composite.
composite aluminium skin is thin enough without then removing more aluminium on one side to sink/hide the fixing.
also, some composites depending on brand and type have a thinner skin again!i have used tons of quality branded composites from dibond, rynabond and the like with channel rail fixings riveted to the rear.
in several instances over a period of about a year, we saw the face being tore from the rails in high wind. basically the rivets were left on the rails, the composite was too soft and the rivets were pulled through the face. granted these were in very remote high wind exposed areas but still… we reverted to using aluminium and it solved the problem.
Nowadays when using a composite on channel rails for any reason we couple up the area thats been riveted with a 3-4 inch strip of general use VHB tape. this spreading the load preventing rivets being pulled thru the face.i know this may sound extreme, but its more a belt and braces exercise if we need to use composite over aluminium. once bitten and all that! 😉
I do pretty much the same as Robert, large panels are aluminium, smaller panels where I use composite I normally tape as well as rivet, belt & braces as Robert says.
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Hi
On a related note,
Is it ok to use countersunk rivets for the corners of sign trays? I have made two so far, one of them I finished off with tek screws, and the second I used wide head rivets.
Both leave a lot of room for improvement.
I think they would look better and more finished if I used countersunk rivets to fix the corners, but I am concerned that they might pull through.
Are they commonly used in this location?
Simon. -
We use a special rivet that opens up inside the ACM, i.e. no visible fixture from the front. It requires a special drill that limits the drill depth as well. Used with Wurth Power Bond adhesive.
We always use 2 fixing methods – 1 chemical and 1 mechanical. Overkill is the Bossman’s middle name……
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quote Gert du Preez:Overkill is the Bossman’s middle name……
Thats a good middle name for me too, Gert!
I will have to google the hidden rivets. I presume you pull them from the inside?
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Hi, Simon,
Just had a look in the store. Sorry. All inscriptions on the box is in Japanese……
The manufacturer is " JAPAN DRIVE-IT CO LTD" …. Being a listed company, you may be able to find them with Google.
The part number is: SD-52-SW-MK 30263-10X0901. The rivet size is 4×12, but they open up inside 3mm ACM. A normal rivet gun is used.
Hope this helps
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Hi Gert
Is it the grooved DH rivets you are talking about?
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Hi, Stuart,
Almost. The ones we have opens up in a "petal". I presume it is almost the same thing, protected by different patents 😀
The example you illustrated should work as well
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At the risk of sounding like a newbie, my 3M tape supplier has insisted that rivets are no longer necessary when using their vhb tape
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They sound like peel rivets from the description Gert, anything like this
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Hi, Martin,
Nope 😀 Almost the same, but the "petals" don’t curl all the way round. I’ll take a picture and post it.
@Ewan: Yes and No. The real VHB (there are a few others with the same claims but dubious performace on the market) is very good, and lasts for years, even with freezing cold etc. My opinion is that VHB, correctly applied, is a suitable method. However, our Architects and Engineers in the 3rd World have to compensate for "less than perfect" installation / materials. That is why they normally request for a "safety" fixture to be included.
BTW, we do full building cladding with ACM, the biggest thus far being (I think) about 15 stories high.
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I can’t see how those peel rivets would work inside 3mm ACM.
Also cant see how the Grooved head rivets would add much to a VHB tape adhesion, but i guess every bit helps.
As its not practically possible to determine the extra safety afforded by adding the rivets to ACM I would as Robert says use Aluminium sheet with riveted channel (usually bought in from Ashby) for anything requiring a high level of safety and for low level low risk areas just use VHB tape on ACM. -
I’ve tried many different tapes and preparation methods and the best solution I found is:
– clean both parts with 3M cleaner (or IPA)
– apply 3M Scotch Weld Tape Primer 83 on both surfaces
– use 3M 5925 VHB tape on the channel – press it with a roller for better adhesion
– stick it to the pannel applying as much pressure as you canThis will hold much better than using just a tape but to be sure I always like to put a few rivets as well. Never cuntersunk composite as it’s not a strong material anyway and taking one layer of aluminium it will make it even less rigid.
Now the other side of all this is that you are probably selling an aluminium composite sign as a cheaper option for the client but if you think about it and add all the time involved to do all the prep work and the cost of the 3M cleaner / tape and primer you will probably find out that it costs you more than just buying a proper 3mm thick aluminium panel ready made with channel to rear from a trade supplier.
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What function does the primer have over and above cleaning?
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It increases the adhesion between the tape and the substrates. I think I could say that it "opens the pores" of the materials allowing the VHB tape to stick better
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Cristian, when you say you have tried many different tapes and preparation methods and come up with the best solution, what criteria or test results have you used to be able to say 3M is better than another VHB tape or UHB tape?
Is is a gut assessment or definitive data?
As I have used other UHB tape and then not need able to physically remove the fixing how can I assess if the bond is any better or worse than a comparison with another make.
The statement you make just sounds like an advert I’m afraid.
Also we have no idea and would like to know if there is any weakening of the bond over time. Say a year or two down the line is a tape bonded fixing any weaker after repeated heating & cooling or wetting? -
Hi Stuart, I am only sharing what I know based on my practical experience and this is the best solution that I am aware of to date (I’m not saying that there aren’t others) and unfortunately the way I got to it was by trial and error. I had signs falling off before (all low level on fences so no risk of injury) but none yet using this method (touch wood).
I took down a sign that has been outside for about one year and tried to take the channel off just to see how strong the bond was and could not take it off without badly damaging the ACM.But as I said initially I always put a few rivets in as well especially if the sign has the potential of hitting someone / something if falling.
To be honest I think that in this process the primer is the one making the difference because I tried using only the tape and the bond was not that strong at first contact. To explain this better – when I accidentally touched the channel to the panel at one end and wanted to lift to reposition – with just the tape I was able to do so easily but when primer was applied I had to cut the tape to get them apart.
I am really sorry that you think that my post was an advert but I can assure you that I am not on the payroll of any suppliers.
Reading it again I don’t know how I could have formulated it differently and actually my last paragraph basically says in other words: don’t waste time and money on tapes and just buy the panel ready made from a trade supplier. I don’t think any sales person would have said this.
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