Bonding aluminum to aluminum - Doable? How?


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    Default Bonding aluminum to aluminum - Doable? How?

    Dear expert machinists:

    Here is the problem: I have a lot of aluminum extrusions, but they are all a little thin: 1/8".
    Now, when I need a thicker piece, I was wondering if I could bond together a few thinner
    pieces, with some type of adhesive, and end up with a material "almost as rigid" as
    the real thing: say, three 2"x1/8" bars to make a 2"x3/8" bar.

    Is this doable? What kind of adhesive would strongly bond aluminun to aluminum?
    Epoxi? How to prepare the surfaces and conduct the cure?

    Thanks a lot for your suggestions

    Nelson

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    Last edited by Arquibaldo; 10-29-2009 at 01:52 AM. Reason: typo


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    Member Kool Parts's Avatar
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    This is a cut and paste of a answer I gave to a similar question a while back.
    Gary

    I have done some extensive testing with different adhesives and 6061. The best by far is Locktite E-30-CL. Used to be known as Locktite glass bonder.

    Its clear and has a 30 min working life. Found this as a tip from a Locktite engineer years ago. He said that it outperformed all of there other products for alum.

    I have put this stuff through shear tests you wouldn't believe..That said it might just eat plastic for lunch! But for $8.00 you get a 50ml twin syringe set...so a pretty cheap test. Part #29329
    Gary




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    To bond aluminium you need to get the epoxy to bond to Al, and not to the oxide. You need a method of stripping off the oxide, then keeping it from reacting with oxygen wheil applying the glue.

    Is this job structural or just decorative.

    Regards,
    Mark


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    Hi Nelson

    Forgive me asking but why? The cost of the glue could exceed the cost of some new bar stock. The problem with any laminated material is that the glue lines represent possible fault lines if the part is stressed. The exceptions being where the laminated material is porus as in wood or cloth where the composite laminate can be stronger than the materials used on their own.

    If the parts are stressed take into account that the glue used may soften with exposure to water or other solvent - shatter under impact - have a restricted usage temperature range. In other word know the glues limits.

    Hope this helps

    Pat



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    Default thanks

    Thanks a lot, fellows - All very good replies.

    RotarySMP : unfortunately, it is a structural job.

    wildwestpat: yes, I know - adhesives have a lot of restrictions - not to mention temperature;
    they are organic compounds, so they give up at 200 to 300 Centigrade max, while most
    metals are still holding...

    My problem is actually the supplier: The people I buy extrusions from only sell them in whole
    pieces, ie: 6 meters minimum. @ around US$12 per kilo, it gets expensive pretty fast for
    the thicker stuff... I have to find someone that sells cut pieces...

    Thanks again

    Nelson

    Last edited by Arquibaldo; 10-29-2009 at 04:55 PM. Reason: typo


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    Member ger21's Avatar
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    Use this before epoxying.
    http://www.westsystem.com/ss/surface-prep

    Gerry

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    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

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    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Unless my math is out, a 6 meter piece of 2" x 3/8" is going to run you about US$95. If it is a paying job, I don't see how it's worth the hassle to bother with epoxy. Actually, even if it is a non-paying job, I would still use a solid extrusion.

    If you can't transport pieces 6 meters long, you could always bring along a hack saw and make 1 or 2 cuts before loading the material into your vehicle.



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    Hi Nelson

    Try ebay or Google for a mail order supplier. Think this is your best bet.

    Regards

    Pat



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    Talking

    Try rivets, in the aircraft industry this is done on structural assemblies that have to stand up to bending and extreme temperature effects. Google for more info...

    My 2¢


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    Yes...it's called welding. Seriously...laminated aluminum extrusions in lieu of using whole material? Sounds dodgy to me. Just make sure you don't try to sell any of that crap to me.



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    Default Thanks again

    ger21: Thanks, I'll see if this product is available here.

    ckirchen: Unfortunately, it isn't a money-making job - it is a money-wasting job: my poor
    attempts at building a tabletop CNC router... Any single expense larger than
    20 or 30 dollars is a red flag in front of "the one who must be obeyed".
    Besides, there is a problem of availability: Thin extrusions are easy to find,
    while anything beyond 1/8" is almost always out-of stock.
    As for transporting the extrusions, I've been doing that for years: they cut the
    pieces in half for me, and they then fit precisely in my car...

    wildwestpat: Yes, ebay... If only I lived in a first-world country...

    bronek: Yes, I know - Rivets aren't practical for me, but I would make sure that no piece
    would depend only on the adhesive - there would always be a few screws
    contributing to keep the laminations together. The adhesive would only be
    responsible for additional rigidity.

    307startup: Very cute and elegant contribution - don't worry - I won't try to sell this crap
    to you or to anyone else - it is crap for strictly private use.

    Nelson

    Last edited by Arquibaldo; 10-29-2009 at 11:06 PM. Reason: typos


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    Well if that is the case, what would be wrong with offset holes in each layer of extrusion, and plug welding these holes as you stack the layers? This would in effect make your available extrusions all one piece.

    _o_o_o_o_
    o_o_o_o_o
    _o_o_o_o_

    Quote Originally Posted by Arquibaldo View Post
    ger21: Thanks, I'll see if this product is available here.

    ckirchen: Unfortunately, it isn't a money-making job - it is a money-wasting job: my poor
    attempts at building a tabletop CNC router... Any single expense larger than
    20 or 30 dollars is a red flag in front of "the one who must be obeyed"
    As for transporting the extrusions, I've been doing that for years: they cut the
    pieces in half for me, and they then fit precisely in my car...

    wildwestpat: Yes, ebay... If only I lived in a first-world country...

    bronek: Yes, I know - Rivets aren't practical for me, but I would make sure that no piece
    would depend only on the adhesive - there would always be a few screws
    contributing to keep the laminations together. The adhesive would only be
    responsible for additional rigidity.

    307startup: Very cute and elegant contribution - don't worry - I won't try to sell this crap
    to you or to anyone else - it is crap for strictly private use.

    Nelson




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    307startup: Thanks, that would be a perfect solution - only trouble is that I don't have
    the equipment to weld aluminum, and I understand it is pretty expensive,
    with all that inert gas stuff, plus it seems to demand a good deal of
    workmanship to operate.

    Nelson



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    Hi Nelson

    Now understand your predicament a bit better. Lucky my wife works part time and I am retired so deliveries are practical!

    If you drill an ream holes at the ends of your length of made up composite and use close fitting pins then the intermediate bolts will only have to clamp the laminations together. Do all the gluing and bolt tightening in one go let it cure for the full time and then drill, ream and fit dowels. The dowels will help prevent any sliding between the laminations as it tries to bend. The holes for the bolts are unlikely to be close enough tolerance unless you do some careful sizing of the bolt shank to suit the diameter of the holes and make sure that the plain shaft of the bolt is the part that fits the first and last lamination - this means using special home made bolts or packing washers to keep all the threaded part out of the hole. As a possible bodge tap the holes and fit studding secured with glue (Locktite if available) and file off after the glue has set. The aim is to stop particularly the outer layers sliding over the others in the lamination pack.

    The thin alloy sections we get in the local DIY outlets here in the UK are a very soft alloy so I hope yours are better quality.

    Hope have a good result.



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    Hey Nelson

    Just read through the thread whilst sipping coffee. I now have four questions for you.

    How long are these two inch sections ? 2 meters?

    How are they to be loaded i.e. as a beam with the 2 inch dimension vertical?

    What load are you going to subject these pieces to?

    How are the pieces to be supported by the rest of your machine?

    I ask as I think there may be a cheaper solution to your domestic problem with finance.


    Many years ago I did some experimental work on laminations in a search for a super strong light weight stable material. Much of this would not be applicable to a home workshop scenario with out a lot of extra gear. However the lamination of thin metal to a balsa wood core was very sucessful. The resulting laminated plank had a very high load capability and was very stiff. The materials used were thin alloy and I think these sheets were less than 0.5mm thick and the balsawood was soft grade and about 5 mm thick. The sandwich of alloy balasa alloy was held together with resin glue under heat and pressure. The glue was applied with a roller and pressure applied with a vacuum blanket but bricks might be good enough. Where load bearing fixings were required round blocks were inserted. The blocks were turned with a deep grove that would have been in the middle of the balsa and glue was liberally applied to the hole and block as it was pushed into place in the previously cured beam. The blocks were pre drilled for the fixings. A latter stage of this work resulted in beams that were 20mm thick and used alloy honeycomb material instead of balsa. The only reason for the change to alloy spacer material was because the customer was teriffied of wood worm!

    Regards

    Pat



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    Has anyone tried this stuff? They mention its like brazing for aluminum

    http://durafix.com/



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    Member Bongodrummer's Avatar
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    Default Re: Bonding aluminum to aluminum - Doable? How?

    Quote Originally Posted by Lexx0001 View Post
    Has anyone tried this stuff? They mention its like brazing for aluminum
    Dura Fix Aluminum Welding Aluminum Brazing Aluminum Soldering & Repair Rod is not sold on Ebay US or Amazon
    I tried something very similar on one of my chainsaw cylinder stove fans (the HTS 2000 brazing rods). I found them very fiddly to use and had mixed success. You can watch a video of my attempts here:
    If you read through the comments on the vid there are some good suggestions for improving the process. If you go the brazing rout, be ready to loose some material while climbing the learning curve!

    Bongo - https://www.youtube.com/flowering_elbow


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Bonding aluminum to aluminum - Doable? How?

Bonding aluminum to aluminum - Doable? How?