Aluminium welding vs brazing

[malkiserow]

Does anyone know the merits of aluminium welding vs brazing on 1mm sheet?

 

I am making some complicated shaped airducts for an amphibious vehicle and although used to some welding and brazing, I am not used to welding Aluminium at all so want to understand how to start (I've done other welding and brazing on mild and silver steel).

 

Cheers

Malk

[webber]

I would find someone who has mastered tig welding aluminium, and give him the job of welding. Quicker and cheaper, maybe not as much fun.

 

webber

[artful badger]

you can mig aluminium with ali wire but it wont be as good as tig, a good engineering shop wont charge much for a small job

[malkiserow]

I should add, I have a MIG welder to use and ali wire.... I was surprised that ali can be brazed and I am very familiar with brazing. It's a paid job for me as I've been working on the engineering and design for about 5 years. I've just taken on making the jigs for the ali fabrication, and these are prototypes not commercial. Function is more important than beauty! I did think of tacking them to basically hold them together for an expert ali welder.

[amateur]

I've used lumiweld rods with a Rothenberger Mapp gas torch to very successfully weld thin section aluminium (16g up to 10mm section)

 

The technique is akin to soldering, and has the advantage that you are unlikely to blow a hole in the thin section ali.

 

It needs much less skill than welding, and the Lumiweld kit is cheap - £13.70 from Frosts http://www.frost.co.uk

 

Although the Frost site says that you can use a butane torch, I have found that you need at least propane, or better still Mapp.

The Rothenberger Mapp gas torch is less than £75

 

The joints, when properly made are structurally sound - I repaired a brake boss on one of my bikes with it and it will certainly handle 1mm aluminium with ease

 

Ian

Edited January 30, 2009 by amateur

[mfletch]

If you do decide to have ago your self dont forget that you will need 100 percent argon gas to weld Ally,

[happyhunt]

you can;t braze ally successfully ,welding is really the only option, lumiweld rods as stated would be the best if you have no experiance, your mig set would require special ally rollers and liner for the torch to feed the wire properly and if you have a tig set it has to be a ac/dc set has ally can only be welded using ac current . if a good job is reqd then maybe get a competent welder to sort it for you.

[tractorboy]

if you decide to braise aluminium get a bar of soap NOT the liquid stuff rub the area to be braised with the soap heat the join until the soap goes black then you start to braise joint with the braising rod till you have finished said join allow to cool then clean area with wire wool .jobs a good un

Edited January 29, 2009 by tractorboy

[peck]

you may find the below link very interesting, i do have some of these rods and they do work very well.

 

http://www.easyweld.com/videos.cfm/vidid/4...ng-with-Durafix

 

if you download the video at the bottom right of the page it shows more detail than the one higher up, both well worth watching.

Edited January 29, 2009 by peck

[amateur]

Good videos - the bloke in the second video made it look very easy - but it does take a little practice to get the temperature right!

 

The Lumiweld kit comes with a stainless abrader that you need to get underneath the aluminium oxides to make a strong joint.

 

The only downside that I've found with Lumiweld is that it is a different colour to aluminium, so on an unpainted piece, even if it has been dressed and polished, you can see the join.

[peck]

a bit like Brucies rug you mean.

[amateur]

[Andy H]

Another alloy soldering product is HTS 2000 similar to durafix , Go onto the HTS website and watch the demo video where he punches a hole in a coke can about 8 mm diameter and then without cleaning it repairs it in about 30 seconds.

[malkiserow]

The Durafix and HTS200 seem very similar. I already have a stainless steel brush.

[jollysp2]

To weld 1mm ali you'd need a ac/dc tig set with foot pedal or a 4 function hf switch trigger. Just normal argon as any other gas only makes your weld pool hotter. Once got that set the set on ac current as dc is for carbon, stainless and copper an the like. The frequency should be about 90hz an amps about 120 ish as everybody is different some people like it a bit hotter as so they can move quicker. Also you would need 2mm ali filler rod. Thats the basics of it without going into detail about pulse settings and different parameters.

 

( Also if you are going to cut the ali best to use a guillotine an not a grinder as some idiots do as that contaminates the steel plus it looks rough then you've to clean it up with acetone )

 

If your not in a rush i'm off from the 7th to the 14th and have alook how much there is to weld then maybe i could bring my set over as only near banbury let me know hope info helps

Edited January 29, 2009 by jollysp2

[amateur]

The Durafix and HTS200 seem very similar. I already have a stainless steel brush.

 

The key thing is that you must not have used it on anything other than aluminium - Lumiweld and the rest depend upon the aluminium being abraded with a clean stainless brush (or aluminium oxide emery paper).