Re: [ATM] soldering aluminum

[Charles Mitchard <charlesmitchard@iinet.net.au>]

Michael Byorick wrote:
> How well does soldering (aluminum) work relative to MIG welding?  I can't
> recall exactly what the issue was (strength?), but several years ago I
> looked into the subject and decided to use epoxy for making a 20" o.d.
> all-aluminum truss tube for a 16" scope.  It worked, btw.
>
> Does anybody know the tradeoffs between welding and soldering, as it would
> seem that there must be something significant, else why would anyone bother
> with tedious welding?!
>
> Cheers,
> Mike Byorick
>   
Hi Mike,
I will give it a go.
soldering uses a lower melting point metal to join two other metals 
together, even dissimilar metals. As its only a "glue" type of joint its 
a lot weaker than welding.
Soldering metals come in a variety of alloys depending upon the parent 
metals to join, ie. gold, silver, copper, brass, steel aluminium etc.
Braising is a stronger form of soldering in that the lower melting point 
metal is brass and is stronger than other solders, usually used for 
various steels.
Welding is a fusion process where the parent metals and a filler alloy 
are all melted and fused together giving a joint that in general is as 
strong as the original metal. (within reason)
For the home handyman there are a few processes that can be used to weld.
Manual Metal arc ie the stick welder, excellent and fast but lots of 
slag to clean off. can be used for steel, stainless, aluminium, takes a 
fair bit of practice but is cheap to start.
Tungsten inert gas, Tig, excellent for most metals and the best for 
aluminium, very expensive equipment to start off.
Metal inert gas, Mig, wire feed welders, fast, simple, easier to learn, 
can join most metals with a choice of wires,very good for steel, ok but 
a bit dirty for stainless, good for aluminium with the correct gas mixtures.
Oxy-acetylene, can be used to join virtually any metal although requires 
a lot of practice to produce an excellent joint on difficult metals.
Soldering aluminium can be done but in general is a very weak joint and 
dont believe the hype from the advertising companies about how strong 
and easy it is.
So, to answer your original question, welding produces a stronger and 
better join than soldering.
In a production environment welding can be automated and and can be 
pretty fast.
There are other forms of welding but in general are not available to the 
home builder.
Epoxy and soldering can produce a strong enough joint for certain jobs 
depending upon its design and how much mechanical strength is required.
Regards
Charles


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