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Any welders in the house? 295

Head Turd Polisher Administrator Just Bananas Posts: 61,350 Optimum instrumentum est inter aures
Any welders in the house?
« on: March 07, 2019, 12:15:13 PM »
I keep seeing ads for these easy aluminum welding rods and they sort of look more like soldering than welding.

I also hear welders talking about how much harder it is to weld aluminum (if not harder, more involved) than steel, and so I wonder about these special rods- are the welds as strong as a normal weld?  Are they strong enough?  Are they only light duty type thing?

It's one of those things I have been curious about for years, and if anyone has any input I would love to hear it.

Def

Leave the dents as they are- let your belongings show their scars as proudly as you do yours.
Just Bananas Posts: 72,236
Re: Any welders in the house?
« Reply #1 on: March 07, 2019, 12:47:47 PM »
Welding aluminium is not easy as it wants to melt too quickly and just burns away
I have seen people use those rods but I don’t think they are much good
I only use a tig welder for aluminium and most of the time I only use low amps
The thing with aluminium is that if you want to weld two pieces together
Is that they don’t want to melt together like with two metal pieces being welded
The aluminium just wants to burn away
It definitely takes longer to learn how to weld aluminium than metal  :tu:


fail to prepare prepare to fail
Zombie Apprentice Posts: 17,515 I'm not a pessimist, I'm an experienced optimist!
Re: Any welders in the house?
« Reply #2 on: March 07, 2019, 01:00:52 PM »
The only thing I've ever welded to aluminium was scrambled egg. The fire was a little too hot I think....



The cantankerous but occasionally useful member, formally known as 50ft-trad
No Life Club Posts: 1,528
Re: Any welders in the house?
« Reply #3 on: March 07, 2019, 02:05:47 PM »
I've MIG welded a fair bit of aluminium 5xxx and 6xxx alloys, and TIG welded a lot less. It is pretty straight forward with the right setup. I haven't stick welded any at all.

That said aluminium has a few things to be aware of regardless of method. Aluminium surfaces quickly forms a layer of aluminium oxide in contact with oxygen (typically air). Aluminium oxide has a far higher metling point than aluminium (roughly 3 times higher if memory serves) and need to be removed before welding - typically grinding will do followed with a bit of acetone cleaning. The welding should then be done in reasonable time afterwards before a new layer of aluminium oxide gets to be a problem. Don't underestimate the importance of this. (Don't leave any acetone rags laying around - they might self-ignite. I speak from experience  :ahhh )

Unlike steel aluminium welds will not be as strong as the base material - a rough figure for the materials I use is about 60% of the base strength. Some prehardened alloys might be much worse off in the weld.

You will rarely if ever encounter products of pure aluminium in the wild. Aluminium is typically used alloyed, and while the big majority is weldable a few are not. That might be worth keeping in mind if you have devilish issues with some rare mystery aluminium material.

Aluminium also leads heat about 6 times as quick as steel, so try to be fairly quick about it to keep the heat affected zone to a minimum. It will typically also deform more during cooling - pre aiming for that or heavy clamping will help.

A good alternative to welding aluminium might be brazing. The sticks I've seen for that are expensive though.



« Last Edit: March 07, 2019, 02:12:47 PM by Vidar »

"If only simple wasn't so hard" - me
(Partial disclosure: I design tools for a living).
Global Moderator Absolute Zombie Club Posts: 21,537
Re: Any welders in the house?
« Reply #4 on: March 07, 2019, 02:13:48 PM »
I have no plans to weld but I do love threads like these.  It looks pretty straight forward but I know with good welding there is some serious skill involved. 

Esse Quam Videri
No Life Club Posts: 1,528
Re: Any welders in the house?
« Reply #5 on: March 07, 2019, 02:23:35 PM »
I keep seeing ads for these easy aluminum welding rods and they sort of look more like soldering than welding.

Somehow I overlooked that one. It might indeed be brazing (hard soldering) rather than welding. It makes a lot of sense for aluminium, and done right the result should be fine for lots of uses. I believe many car manufacturers use brazing for aluminium.

Among the positive sides for brazing is typically less heat so less deformation, many forms of brazing are very effective in production (quick induction heating, baking, clean result), and one can braze materials that will not weld together with normal methods.

"If only simple wasn't so hard" - me
(Partial disclosure: I design tools for a living).
Zombie Apprentice Posts: 14,596 Firm believer of Sturgeon's Law
Re: Any welders in the house?
« Reply #6 on: March 07, 2019, 04:35:18 PM »

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Global Moderator Abandon All Hope Ye Who Enter Here... Posts: 46,555
Re: Any welders in the house?
« Reply #7 on: March 07, 2019, 06:12:01 PM »
This is a good video of an average Joe giving it a try.

https://www.youtube.com/watch?v=CJ42scaWFnw
No Life Club Posts: 1,528
Re: Any welders in the house?
« Reply #8 on: March 07, 2019, 06:50:21 PM »
This is a good video of an average Joe giving it a try.

Or the more likely to succed way:   

Clean the parts, place them with a tiny gap in between, add flux (some rods have that already), heat the part (not the rod), touch with brazing rod as needed and watch flux and capilary action drag the material in between the parts.

(Rather than trying to join the thin sharp edges of plates it would also be a good idea to overlap the plates to get more surface area in between for the brazing to connect to).

This video is more traditional brazing: (I assume the rod here have flux). 

https://www.youtube.com/watch?v=3SBfP4_i1Go

 
« Last Edit: March 07, 2019, 07:24:37 PM by Vidar »

"If only simple wasn't so hard" - me
(Partial disclosure: I design tools for a living).
Head Turd Polisher Administrator Just Bananas Posts: 61,350 Optimum instrumentum est inter aures
Re: Any welders in the house?
« Reply #9 on: March 07, 2019, 07:41:43 PM »
That looks a lot stronger than I was expecting it to be.  I think I may have to give some of those rods a try.  I like to work with aluminum as it is easy to work with, light, strong and resists corrosion very well.  I have just always shied away from welding/braising/soldering (whatever this is) as I had heard that welding aluminum was problematic and you needed special gear/skills/conditions etc to do it properly. 

If this is as strong as it looks then maybe I was wrong to dismiss it as a gimmick.

Def

Leave the dents as they are- let your belongings show their scars as proudly as you do yours.
No Life Club Posts: 1,528
Re: Any welders in the house?
« Reply #10 on: March 07, 2019, 10:51:22 PM »
That looks a lot stronger than I was expecting it to be.  I think I may have to give some of those rods a try.  I like to work with aluminum as it is easy to work with, light, strong and resists corrosion very well.  I have just always shied away from welding/braising/soldering (whatever this is) as I had heard that welding aluminum was problematic and you needed special gear/skills/conditions etc to do it properly. 

If this is as strong as it looks then maybe I was wrong to dismiss it as a gimmick.

Def

Brazing is definately not a gimmick, but it isn't a solution for everything either. I would look to it for fixing leaks, joining thin or dissimilar materials or joints of less than critical nature. I would be vary using it for joints with little surface area or small fillets, and maybe especially if the joint will be exposed to fatigue. Due to the cost of the brazing material I guess it wouldn't be an option for big stuff either.

Another thing to check out if corrosion is a factor is whether or not the brazing rod in question includes zinc. Many of them have quite a bit.

For thicker or bigger parts I would simply suggest a MIG welder with aluminium setup: Argon cover gas, fairly thick wire, teflon hose liner, and 4 roller feed. Then use a fair bit of amps and make very sure to push and not pull the gun. (If it looks dark and porous you've likely pulled the gun - or forgot the gas). It isn't hard at all, but it is different from steel, which I think is the main issue for many.

If corrosion is a factor go for 5xxx or 6xxx series aluminium and 5xxx wire. Same wire if you plan to anodize the part later - 4xxx series wire will turn black in anodizing due to the silicon content. 
« Last Edit: March 07, 2019, 10:53:08 PM by Vidar »

"If only simple wasn't so hard" - me
(Partial disclosure: I design tools for a living).
Global Moderator Abandon All Hope Ye Who Enter Here... Posts: 46,555
Re: Any welders in the house?
« Reply #11 on: March 08, 2019, 11:47:55 PM »
No Life Club Posts: 1,528
Re: Any welders in the house?
« Reply #12 on: March 09, 2019, 01:03:11 AM »
This is a great video

That was a nice one. Especially interesting with the very thin stuff and the thread repair. :cheers:

"If only simple wasn't so hard" - me
(Partial disclosure: I design tools for a living).

 

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