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Mig brazing question


kencombs

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Does anyone have first hand experience with MIG brazing? 

Silicone bronze may be the best for a project I'm working on due to its' being softer than cast or steel ..  It should be easy to drill, tap and grind.   I hesitate to invest in a tank of gas and roll of expensive wire if you guys have some negative feedback.   

 

Edited by kencombs
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For others like me who have never heard of this weld type - a web search came up with this- -

 

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

 

DJ

 

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Yeah, I've scoured the web and found a lot of info  Everything looks good but was hoping for some real life feedback.

 

More on my plans:  I'm adding an A833 OD trans to a mid 50s pickup clutch housing.  The center hole fits the big front bearing retainer correctly but the housing itself need to be built up in areas where the bolts will go as the mounting flat is too small..  Plan was to use some cast stick rod that is purported to be 'machinable'.  Thats important since I'll need to drill, tap and mill the filled area. 

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I don’t have personal experience but have been looking at silicone bronze Mig wire to fill in the body seams at the top of the cab. A two pound roll is available online for less than $40 if your welder will take the smaller rolls. I already have a bottle of argon for aluminum.

 

Since it is a softer material, my thought was to weld up the seams then file/sand it down to get the original look. The lower melting temp should help limit metal distortion while providing a good seal.

 

Hopefully, someone with experience using it will respond and let us both know how well it works.

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It seems the some high end car makers now specify silicone bronze for structural body part replacement.  The lower heat doesn't change the steel properties as would welding.  But, my planned use is much different.  I would do 'normal' braze, but find it difficult to get parts as large as a clutch housing to the right temp for good adhesion.  takes a long time to heat and cool.  Mig would be so much faster.  And, as mentioned in my first post, stick weld may not be machinable when done.  Sure hope someone with some experience chimes in.

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I have used silicon-bronze with the tig process extensively. It (silicon-broze) has a very narrow application suitability. It is best used for very close tolerance fitting where much of the joint (if not all) derives its strength from the base material, not the brazed joint. Think of it as glue, more than a weld. It has very limited application in repair welds/brazes.

It sounds like you DO NOT want to use this on your bellhousing. Standard stick-arc wit appropriate rods should work fine. Just make sure the cooling process does not permit the material to over-harden. This sounds like a job for an experienced welder/fabricator.

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2 hours ago, jeffsunzeri said:

I have used silicon-bronze with the tig process extensively. It (silicon-broze) has a very narrow application suitability. It is best used for very close tolerance fitting where much of the joint (if not all) derives its strength from the base material, not the brazed joint. Think of it as glue, more than a weld. It has very limited application in repair welds/brazes.

It sounds like you DO NOT want to use this on your bellhousing. Standard stick-arc wit appropriate rods should work fine. Just make sure the cooling process does not permit the material to over-harden. This sounds like a job for an experienced welder/fabricator.

Thanks for the input.  In this application, there is really no joint,  No two parts being adhered, whether weld or glue.  Just a material build to 'flatten' the area that will then be threaded.  our comment on the 'over-harden' risk is exactly why I was considering the silicon-bronze filler from my mig. 

 

I've brazed cast with 'normal' rod successfully in the past, but it really hard to properly preheat a part as large as the clutch housing and get the brazed area  hot enough to bond well.  At least it has been for me.  Manifolds and small parts are easy, but 50+ lbs takes awhile.

 

I think I'll try the rods I have for my stick machine on a scrap housing and then decide.  They are a proprietary rod with no AWS spec, so who knows.

Edited by kencombs
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