Welding Tips and Tricks

OK. Tomorrow I have to repair a dent in a mold and sure could get some advice.
It's 2024 aluminum, .75 inch thick, and the divot is a compression fault due to a bit of polyurethane getting squished with 33 tons of force. Both plastic and mold lost that war.

Anyway it's a crater about .005 deep and .100 wide causing flash on the side of the parts.

I have a microtig machine but I don't know if I can use it for aluminum. It's polarity is fixed.

Before I started welding I would have fixed this type damage with a center punch and squish metal into the damage. I may still have to.

Thanks for your attention.

2024 is basically....NOT WELDABLE, per Alcotech, etc.....and the personal experience
of your's truly and a host of others.

Thanks! I may have to try on some scrap. It's not really structural. It just has to fill space and stay put. Mcmaster Carr probably isn't the best source but says it's marginally doable.

If you can source some 2024 sheet, cut a strip to use as filler.

I've seen .040" 2024 T 3 welded using this method. And the job went out the door......

There are tool and die shops that have the experience for this type of repair. I couldn't see myself risking a customer if I caused more damage. Helping people get the best result usually adds up in the long run.

This is an example of a shop that can, at the least, provide some insight. http://www.microprecisionwelding.com/
It doesn't mention 2024 but I noticed 7075 and copper alloys on their site. It is a mold and not structural, so maybe there is some hope.

I admire your enthusiasm and I'm curious to know how it works out.

Thanks for the kind words. I had success. I hand milled 2 divots near the damage. I set 35% clean with max amps at 60. 3/32 lanthanum and 1/16 4043. Took a deep breath and hit it hard on the away side of my divot. The sharp edge melted for a sec and I dabbed quickly then moved the arc to coax the added metal to fill the hole. Then did the 2nd hole after brushing. I did use a hammer and punch to squish metal in the cavity area. If I were braver I might have welded the whole thing, but didnt.
4043 worked okay. I like it cause it's harder than 5943.

I think it turned out well. Did an overnight run no prob.
Before I got into welding I would have drilled a hole bigger than the damage, plugged it and recut the cavities.

This all happened because the end user pulls parts off the runner and wants no nubby gate vestige. I made the gates just large enough to avoid short shots, but the weak gate broke during mold opening and the little part got squished on the next mold close. They're tiny so mold protection pressure can't help with this.

The last mold for these was of 6061 and lasted 15 years, prob. 250,000 cycles. This one I made of 2024 since it's harder, I'll start using steel I think.

Catch 22 is steel is easier to fix but harder to damage................ I like making aluminum molds. Quick and easy.

Bottom line, the gates are larger now. This won't happen again. Unless a worker gets careless with hand tools.

2024 has copper as one of the alloying elements. When welded, the copper precipitates out, changing to material properties. While you can weld it, the corrosion resistance and crack resistance and most likely the tensile strength will all be negatively impacted.

dgapilot wrote:2024 has copper as one of the alloying elements. When welded, the copper precipitates out, changing to material properties. While you can weld it, the corrosion resistance and crack resistance and most likely the tensile strength will all be negatively impacted.

Amen. The experience I had with TIG welding, thin-.040-.050 formed, 2024 sheet stock for crack repair was:
Filler flowed, wetted well, bead 'looked good'...but this then revealed very tight cracking on both top
and bottom sides, at the juncture of the puddle melt to the parent 2024; affirming the statement by Alcotech and others
that 2024 is considered un-weldable by normal means.
This die repair is an r&d project, which may work long term or not. Depends on how much and what form of stress
is imparted to the affected weld and HAZ area.
Try welding sheet or wrought 2024 stock and you'll get the results that I did.