cast aluminum welding

[stretch]

Can I weld a cast aluminum throttle body to a non cast piece of aluminum? A buddy asked me this and I said I have no idea. Anyone ever done this?

[shovelon]

Yes.

[stretch]

Ok so if I were to do this for him, how would I go about it. He said he has a piece I can practice on. From what i've read so far it needs to be really clean and I have to pre heat. Right? What kind of filler is best? I've never welded cast aluminum and I think its time to try. Any help would be greatly appreciated!

[welder_one]

other than bein dirty and porous and taking more heat, it welds pretty much like....aluminum

no fear, just stick em together, point the torch n wiggle it around

[SundownIII]

stretch,

You may find the need to "butter" the cast before you attempt to weld the two pieces together.

This "buttering" involves laying down a base of filler. Generally, when welding cast that first application of filler will be "dirty" and porous. Grind it down, and apply new filler. You'll find with each subsequent application of filler, the base metal gets cleaner and cleaner.

Then it's considerably easier to get a good weld between the two materials. Your standard 4043 filler should work fine.

[shovelon]

stretch,

You may find the need to "butter" the cast before you attempt to weld the two pieces together.

This "buttering" involves laying down a base of filler. Generally, when welding cast that first application of filler will be "dirty" and porous. Grind it down, and apply new filler. You'll find with each subsequent application of filler, the base metal gets cleaner and cleaner.

Then it's considerably easier to get a good weld between the two materials. Your standard 4043 filler should work fine.

Two thumbs up!

Good advice SundownIII.

[stretch]

So your saying to flush the two pieces together and weld them up? Then grind it flush, or should I remove the whole weld and start over?

[karchiba]

You may also try 5356 rod, which is formulated for welding Aluminum casting.

[SundownIII]

stretch,

What I'm saying is that proper "prep" of the cast, before you try to join the two pieces, will give better results.

If you go willy nilly into welding the formed aluminum to the cast, without prepping the cast, you'll likely pull junk from the cast into the newly formed weld bead.

As with all metals and especially aluminum, proper prep of the material will always result in a "better weld".

[JSFAB]

just to clarify, "buttering" is done before attempting to join any two pieces together.

[stretch]

So what your saying is to lay a bead on just the edge of the cast a few times before joining the two together?

[kcstott]

That's the key

The other thing is some cast material welds like billet plate and some cast welds like mud.

I welded up a manual transmission shifter housing for my buddy and with proper cleaning and preheat it welded like it was machined from solid

[yorkiepap]

Hey stretch,
I agree with SundownIII also with the "buttering" technique, & your concern would be the impurities that surfaced. You need only to remove the contaminants from the buttering applied & not necessarily back to the original surface. Generally, a good brushing w/SS brush & acetone again will remove any residual impurities. You can leave the clean buttering on each piece. A good preheat will help, & I would suggest not using 5356 as it is temp. affected above 150* & an engine block will heat higher than that. I do use 5356 for all the cast welding I do when the parts are not subject to heat.....over 150*, use 4043.

Denny

[Portable Welder]

Stretch, unfortunately I have to disagree with what they called buttering the cast.

Clean the cast with a wire brush and acetone before trying to weld ( Make it shiny )

Then take your tig torch over the area to be welded at a slightly lower temputure than what you would weld the piece at, Doing so will bring the contamination to the top, I then take my die grinders that I have carbide cutters and a wire wheel on and make the weld area shiny again.

Keep doing this process until very little contamination comes to the top ( This usually takes 2-3 times )

You are then ready to pick up the welding rod and start welding.

Using the method they called buttering only traps the contamination inside causing a weak area.

Stretch, I did not mention Vee grooving the crack I assume you already know to do that.

Good Luck, Portable Welder

[SundownIII]

Portable Welder,

If you do what you're proposing two or three times (heat, draw impurities, grind), in many cases you're not going to have any base metal left.

The "buttering" involves adding fresh, clean filler material as you're heating the material up, thereby drawing impurities into the bead. This is then ground down to near the original base metal. Each time the process is repeated the bead, which will be ground down to the original profile, gets cleaner and cleaner. I use a carbide burr for grinding.

The process you describe (not adding filler) simply brings the contaminants to the surface where they're ground off. As you repeat the process, without adding filler, you're simply going deeper and deeper into the base metal.

The "buttering" process I describes is not something I simply read in a book somewhere, it's a process I've used with good success for over thirty five years in dealing with aluminum. Outboard motors have been using cast aluminum blocks for a lot longer than the automobile industry.

How do you suggest the OP maintain a surface profile/original dimension without adding filler?