Welding Mounting Studs onto Aluminum, Waterjet-cut Emblems (jakeru's #1)

[jakeru]

I welded some aluminum mounting studs onto some waterjet cut aluminum plate. Did two of these.


The waterjet-cut plate was 1/4" thick 6061-T6. Shown prior to welding the studs on:


The studs were 1/4-20 size, 5000 series aluminum; a good selection for high as-welded strength. The studs had a shoulder that I basically melted into the thick plate material autogenously (no filler rod added.) A shouldered weld-on stud, before and after welding:


Settings: for maximum penetration, I went with an Ar/He mix (2.5 cfh He, 12.5 cfh Ar), and I used the torch switch to trigger a very brief, "all or nothing" 200 amps, along with the minimum cleaning (20% EP) AC Balance setting on my Super200P. I used a 1/16" tungsten with truncated point (sharp with flat.)

I performed the welding in two passes:

#1 - stuck the sharpened tungsten down very far in the fillet between the stud shoulder and flat plate - almost touching. Although often the puddle would melt onto the tungsten, it would ensure the two materials would successfully flow together (making a weak tack weld of sorts.)

#2 - after cleaning off the aluminum contamination from the tip of the tungsten, I made a second pass around the welded area, holding the tungsten a bit further back this time, so the puddle did not touch it. I flashed the arc for a bit longer, making the puddle melt wider and most importantly, deeper, for increased penetration and added strength.



It's a pretty small, delicate part to weld onto a comparatively thick plate, but I would say this technique did the trick.

Oh almost forgot, I used a welder's finger (Aka "third hand") to quickly hold the studs in position for the initial tack welds, and also for grounding. They are really useful for holding small aluminum pieces like these for tack welding.

[jakeru]

I did some more of these, on thinner (1/8" thick) material, and the same size studs. It worked OK, using the same machine settings and technique, and just using pure argon instead of Ar/He mix instead, and perhaps holding the arc a bit longer on the second pass to get it to "melt in" better. I was a bit concerned about over penetrating into the 1/8" material with the Helium mix (and He is pricey, so not worth using unless its really needed.)

Although the puddle didn't penetrate all the way through or anything, the 1/8" plate did deform ever so slightly; "rippling" the outline of the stud interface on the back side (which is the side that will actually show when these plates are "mounted".) It rippled from the relatively thinner material not being rigid enough to withstand the cooling-related contraction forces. It does show I got some decent penetration though, I think. Weld should be strong.

[geezer]

Looks easy until a person trys it, welding them plumb takes some doing. Nice work

[SeanMurphy265]

Is that your water jet?

[jakeru]

Thanks, Geezer.

SeanMurphy - the customer supplied them already waterjet cut.

[CGCINC]

Could you weld these without filler rod, just using the lip on the stud as filler?(I know it's not a big lip) Maybe set to pulse and go slow around the stud?

Just wondering for my personal knowledge.....

[jakeru]

That's how I did it. (No filler rod.) I did another batch of these since I posted this.