Technical New to me welding process - MIG Brazing

Well, it's not really welding, it's MIG brazing. I visited a restoration shop the other day and there was a guy doing some patch panel replacement. His MIG welder sounded sick, like the current was too low. I didn't say anything but the owner pointed out to me that they were now MIG brazing patch panels with a new machine that he had recently bought. He added, "it sounds funny, doesn't it?". Yeah.

After looking at some of the spot "welds" he had laid, it looked just like it would have with MIG weld but there was no distortion. He explained to me that that was why they had changed. It's quicker because there is a lot less hammer and dolly work to be done, it the panel is fitted properly.

Do any of you have experience with this? What is your opinion? I've done a little silicon bronze TIG brazing but nothing like this. Can you use a standard MIG machine to do it? Inquiring minds want to know more.

 

Interesting. Did you happen to get a look at the machine?

 

Interesting. I’ve never seen this type of brazing.

 

I found this on the Miller site.

MIG brazing benefits
MIG brazing may not be a familiar process to many, but it is no stranger in the welding world. MIG brazing is a welding process that has been around for years and is gaining popularity with professionals and hobbyists alike due to the benefits it can offer, especially with silicon bronze filler metal.

Learn about MIG brazing, silicon bronze and how to properly set up your welding power source for MIG brazing silicon bronze.

What is MIG brazing?
Brazing processes have traditionally used an oxy-fuel acetylene torch to melt the filler metal, but in MIG brazing, a standard MIG gun is used to run brazing wire. Brazing filler metal melts at 840 degrees Fahrenheit, which is lower than the melting point of the base metals being joined. Due to the lower melting point, the filler metal provides capillary action — fluid being drawn into the weld joint — when brazed.

What is silicon bronze?
Silicon bronze filler metal is mostly comprised of copper, silicon, tin, iron and zinc. The composition of the wire provides some unique benefits such as the ability to weld dissimilar metals together, reduce distortion and provide a visually appealing finish.

Welding dissimilar metals
When braze welding with silicon bronze filler metal, the molten metal bonds the base materials together but does not provide fusion like mild steel filler metal. Because of this, silicon bronze can be used for welding together dissimilar materials such as cast iron to steel or stainless steel to steel.

Reducing distortion
The low melting point of silicon bronze also provides a cooler welding process, putting less heat into the material that is being welded. Reduction in heat input leads to less distortion and the ability to weld on heat-sensitive materials without compromising the physical properties. It is ideal for joining thinner metals together, filling gaps, and sheet metal work such as HVAC and auto body welding.

Gold finish
When done correctly, a silicon bronze weld will have a gold colored finish that provides contrast to the base metal. Gold colored welds are often used for aesthetic appeal in metal art applications.

There are a few disadvantages of the MIG brazing process to consider. Silicon bronze wire is generally more expensive than mild steel wire. Because of its composition, the wire is softer than a mild steel wire, meaning it can occasionally cause bird-nesting or other feeding issues. It also has a lower tensile strength than mild steel wire.

Machine setup
MIG brazing can be done with short-circuit transfer, and the arc characteristics are similar to a mild steel filler metal arc.

When setting up your machine for MIG brazing, there are several key components that must be correct to achieve the best results possible.

• Shielding gas: It is critical that 100% argon shielding gas is used with silicon bronze wire.
• Drive rolls: Because silicon bronze wire is softer than steel, U-groove drive rolls are recommended, but V-groove drive rolls will also work.
• Process selection: When setting up this process on your MIG welder or multiprocess welder, set the machine to the C25 setting for the best results.
• Polarity: Polarity should be set to DCEP.
• Gun liner: A Teflon liner is recommended due to the softness of the silicon bronze wire, but a regular steel liner will also work.
• Technique: When MIG brazing, use the same welding technique used for short-circuit MIG.

Miller has developed parameters for MIG brazing silicon bronze for Millermatic® MIG welders and Multimatic® multiprocess welders. PDFs of the parameters are available for reference:

 

It was not a brand that I was familiar with. I believe he said it was Italian. It appears you can do it with any MIG machine, if set up properly. See my previous post.

I would love to get Robert at @MP&C to comment.

 

Now I wonder why my Miller store guy hasn't bothered to mention this.....he knows that I have some cracked blocks in the shop to deal with ...

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It is being used now in the collision industry so that the heat of regular MIG welding doesn't change the structural properties of the high strength steels being used in today's vehicles. Some traditional machines will work but most vehicle manufacturers require a pulse welder be used to achieve proper weld strength. That is probably the "sick" sounding welder you heard.

 

I have been doing it for a few years now, with good results.

I am using standard Miller rollers. You need a good, fresh gun liner, and to keep your tips clean. Polarity does make a difference, for sure, so make sure you check to see where your leads go.

The C25 amperage settings are indeed a good starting point, but mostly I am on the lowest setting almost all of the time. This is with straight Argon, on my regular old Miller.

Standard panel welding techniques still apply. Tack-check-grind, and NEVER compressed air cool, just like regular MIG. The SiBr grinds much easier too!

 

Going to have to check to see if they make spool gun sized rolls, would save changing setup on the welder

 

Yup: https://store.cyberweld.com/haersibrmigw.html

It is a 2lb. spool. It is the same size as a 3lb. ER70 spool, but the filler material is lighter.

 

All ear's!
So name a few brands of MIG"S that are friendly to convert?

 

I have a Millermatic 210, circa 2002, with a Tweco gun. No mods.

The gun has a fairly long lead, so I have to take care that I keep it as straight as possible. The wire is soft.

 

I always heard that copper, br***, bronze shouldn't be used on body panel welding? How does this work?

 

Millermatic 140 Auto Set ?
Would like to see a weld that is ground down?

 

That is a myth. This got started way back in the days of torch brazing. Unknowing, or lazy folks doing bodywork would not bother to fully remove the flux that allows the metal to flow. Over time, that flux layer allowed subsequent filler and paint to fall off. It is not the low temperature metal that is the issue, it is the flux.

When you use SiBr in a MIG welder, there is no flux.

 

I don't see why not.

 

Rockable, can you provide a link to what you found? I can't find what you have...

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https://www.millerwelds.com/resources/article-library/silicon-bronze-mig-brazing-basics

 

...damn, you are fast........

 

For the record, you can highlight long unique phrases in text, and do a web search for them.



If you have a PC, hold your left mouse ****on down, and sweep the cursor across a unique phrase. Release the ****on. Click the right mouse ****on. There should be a choice in the menu that appears to do a web search, or to search Google.

This will vary on a Mac, but someone may chime in.

 

So, it appears to me that I can hook my argon bottle from my TIG up to my MIG, change polarity and just install a spool of wire to try this. I don't have any work to do right now but I will probably experiment with it some.

Thanks for all the replies, especially Gimpy!

 

I 've had this DipStick 160 for over 40 years use it all the time, has the MIG plus the Stick, plus the Spot Weld "s***ch" mode. Wanted to put a HF TIG box on it BUT the local welding supplier say it shouldn't have lived this long and won't last much longer, they have been saying that for 20 years now. Anyway instead of "joining" a welding forum I will ask first here, would this be a good candidate for MIG brazing?

 

Hey! I have one of those too, with the HF box on top! I keep fluxcore in the roll tho, and only use the Tig with the Argon bottle. Sure would like to figure out a foot pedal for the Tig tho, the HF keeps the rod in better shape when starting tho, seems to allow the arc to “jump” to the metal easier.

Mine might be newer or older, it has a hand crank on it as well

Edit: I see your hand crank as well

 

Please explain why we should s**** our TIG units. What grinding disks are best for Super Braze?

 

I don’t think anyone is suggesting to s**** your Tig, but this seems like a way to not have to buy another machine...***uming one already has a wire feed welder

 

I sure wouldn't s**** my TIG but I find it difficult to weld out of position with my foot control. I have never tried the hand/finger controls. MIG is just so easy for most body repairs.

 

I would use the same 3M 50 grit or 36 grit roloc sanding discs I normally use.

 

Good thread Thanks rockable for bringing it up for discussion. I am going to look into it since I am in the midst of a lot of sheet metal work right now.

 

Kinda corney: