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Thread: cant weld aluminium for shit - advice ??

  1. #31
    Registered User MWP's Avatar
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    Quote Originally Posted by sssgtr View Post
    Minimise your cleaning cycle to the bare minimum on thin material. I found that too much cleaning was putting too much heat into the material, causing it to drop away before I could get filler near it.
    Isn't it the other way around?
    More cleaning puts heat into the tip, less cleaning puts more heat into the metal.

  2. #32
    BLING BLING PLAYA's Avatar
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    There is a lot of mis match of words going on here.

    Frequency is just how quickly it flicks polarity.

    Duty cycle really is how long you can stay welding for before machine overheats.

    Balance is % of negative vs positive or cleaning vs penetration per cycle.

    But all in all what they are saying is correct.
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  3. #33
    Problem? sssgtr's Avatar
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    I probably did have it around the wrong way, point is, don't leave it at 50% if you don't need that much cleaning action.

    I think I run somewhere on 30% with my machine.

  4. #34
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    Quote Originally Posted by PLAYA View Post
    There is a lot of mis match of words going on here.

    Frequency is just how quickly it flicks polarity. Yes, the frequency of the output power.

    Duty cycle really is how long you can stay welding for before machine overheats. That is the welder's duty cycle, yes. But in this context, it's the percentage of time the output waveform is postive or negative.

    Balance is % of negative vs positive or cleaning vs penetration per cycle. This is known as the duty cycle in all other electrical fields, it's only in specific welder speak that balance = duty cycle.

    But all in all what they are saying is correct.
    I generally run 30 to 40 % duty cycle on mine for less-than-moderate cleaning action on extruded stuff, and longer tungsten life. On thin stuff, upping it to 70% quickly heats the tungsten but avoids droop, as long as you've wirebrushed the absolute shit out of the thin aluminum. (welding light sheet end tanks on intercooler cores and 1.5mm charge piping) When working on cylinder heads, if it's a clean casting I can usually work around 50%, but if it's old, oily, and greasy, I'll still have to do a "de-grease" pass by running very high duty cycle, then re-grind the tungsten (it picks up all the shit that comes out of the aluminum-so get used to re-grinding it often for very oxidized or dirty aluminum.) and run a very low duty cycle pass to put a LOT of heat into that area of the casting, which brings up even more crap. Another high duty cycle pass to rip all the crap out of the weld area, re-point the tungsten again and then back to 50% for doing a clean-ish casting.

  5. #35
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    Just from the first post, it sounds like you're running on DC neg, or have your AC balance heavily that way. The biggest problem with AC balance is that different manufacturers label their welders differently, hence one of the guys above say about 70% works good, another says 30% does. They will actually both be at the same point, just one has a machine that displays positive balance and the other, negative balance (or they could be using the same machine but one of them has his welding leads hooked up the opposite way). Some manufactures will even display a zero in a central location, with plus and minus numbers either side of it. In this case the "zero" generally around 70% actual balance.

    Anyway, just as a test, set your AC balance to 70% and try and run a bead on some scrap plate. If you have the same issue, swap your leads on the machine and try again. It might weld good or it might melt the tungsten away (both indicate incorrect AC balance being the problem), or it might do the same thing, or it might do something completely different, indicating a material issue or a combination of both.

  6. #36
    Gas Turbine enthusiast da9jeff's Avatar
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    Quote Originally Posted by Xnke View Post
    I generally run 30 to 40 % duty cycle on mine for less-than-moderate cleaning action on extruded stuff, and longer tungsten life. On thin stuff, upping it to 70% quickly heats the tungsten but avoids droop, as long as you've wirebrushed the absolute shit out of the thin aluminum. (welding light sheet end tanks on intercooler cores and 1.5mm charge piping) When working on cylinder heads, if it's a clean casting I can usually work around 50%, but if it's old, oily, and greasy, I'll still have to do a "de-grease" pass by running very high duty cycle, then re-grind the tungsten (it picks up all the shit that comes out of the aluminum-so get used to re-grinding it often for very oxidized or dirty aluminum.) and run a very low duty cycle pass to put a LOT of heat into that area of the casting, which brings up even more crap. Another high duty cycle pass to rip all the crap out of the weld area, re-point the tungsten again and then back to 50% for doing a clean-ish casting.
    You've just confused everyone in this thread.

    In welder land duty cycle is how long you can weld vs off time ie 30% on = 70% off before it overheats/trips a thermal switch.

    Balance is the % time the output is electrode negative vs electrode positive.

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  7. #37
    Registered User MWP's Avatar
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    "Duty cycle" can be confusing because to electrical/electronics guys it means something different.
    To us duty cycle is % on time for pwm... which funnily enough is exactly what "balance" is in tig welding.
    But yeah, this is about welding, need to stick to the welding meanings of the words.

  8. #38
    Problem? sssgtr's Avatar
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    I was referring to percentage output in AC vs DC in my post/s - "amount" of cleaning action.

    As already stated, wirebrush and acetone clean reduces heat required for cleaning - try and just see what works for yourself.

  9. #39
    BLING BLING PLAYA's Avatar
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    I think what we should do to make it real easy for everyone is we will use the word duty cycle for how long your machine can operate, balance, and also pulse.
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  10. #40
    Gas Turbine enthusiast da9jeff's Avatar
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    Quote Originally Posted by sssgtr View Post
    I was referring to percentage output in AC vs DC in my post/s - "amount" of cleaning action.

    As already stated, wirebrush and acetone clean reduces heat required for cleaning - try and just see what works for yourself.
    This is still wrong lol. Ac means that it switches between electrode negative and electrode positive. It doesn't switch between ac and dc.

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  11. #41
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    Hahahahaha, fml. Glad you knew what I meant to say!

  12. #42
    GTFO of my ED doctor ed's Avatar
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    seems I stirred up a decent thread for change

    after procuring my stainless brush set and grinding stuff for my tungsten, ive been preoccupied with doing stainless exhaust work, and haven't gotten back to trying alloy again... went to attack some scrap the other day and find ive now run out of gas... yay

    interesting comments above though, im running a lens and pyrex cup, but have continued to keep the gas flow the same as with the normal cup (10-12). I hasn't effected the quality of my stainless stuff to date, but ill def have a bit more of a look, and pay attention to the colouring more. also have a look at what its doing with the alloy. good tips, keep em coming!

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  13. #43
    Registered User Dimi's Avatar
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    Quote Originally Posted by PLAYA View Post
    I think what we should do to make it real easy for everyone is we will use the word duty cycle for how long your machine can operate, balance, and also pulse.
    Yes exactly, cooked my brain reading that.



    And unless old mate is using an older transformer machine at a fixed frequency, using AC balance as a band aid for material thickness is probably the wrong way to go.

  14. #44
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    Raising the frequency helps to tighten and focus your arc to a tighter, more stable pinpoint, but it doesn't change the heat distribution in the arc. AC balance is the only way to move heat from the tungsten tip to the workpiece and vise-versa. It is one of those "fuck it, this shit is doing my head in" fixes for getting a stable enough arc to burn the oxides off without melting the base metal.

  15. #45
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    Quote Originally Posted by Xnke View Post
    Raising the frequency helps to tighten and focus your arc to a tighter, more stable pinpoint, but it doesn't change the heat distribution in the arc. AC balance is the only way to move heat from the tungsten tip to the workpiece and vise-versa. It is one of those "fuck it, this shit is doing my head in" fixes for getting a stable enough arc to burn the oxides off without melting the base metal.
    You need to melt the base metal in order to weld it?
    In order to do that i don't want to move heat from the material to the tungsten. I want to heat the material as quickly as possible so i can add filler and get moving.
    Regardless of your heat distribution or whatever you want to call it, aluminium's melting point doesn't change because of your AC balance or frequency or anything else. All you are doing is slowing down the time it takes for heat to build up in the material and form a puddle.

    The simple answer is. Increase your initial amperage to form a puddle quickly, increase your travel speed. Because you work too slow and you heat the surrounding metal, you are overheating the material that's why its falling away as you described.

    Just so you know i'm not saying you are wrong, sometimes you have to do what whatever to get the job done. I'm trying to say there is a better way although i'm not sure how to put that into effective words on internet.

  16. #46
    Bannered takai's Avatar
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    Quote Originally Posted by Dimi View Post
    You need to melt the base metal in order to weld it?
    In order to do that i don't want to move heat from the material to the tungsten. I want to heat the material as quickly as possible so i can add filler and get moving.
    Regardless of your heat distribution or whatever you want to call it, aluminium's melting point doesn't change because of your AC balance or frequency or anything else. All you are doing is slowing down the time it takes for heat to build up in the material and form a puddle.

    The simple answer is. Increase your initial amperage to form a puddle quickly, increase your travel speed. Because you work too slow and you heat the surrounding metal, you are overheating the material that's why its falling away as you described.

    Just so you know i'm not saying you are wrong, sometimes you have to do what whatever to get the job done. I'm trying to say there is a better way although i'm not sure how to put that into effective words on internet.
    It is all well and good to just say increase travel speed, but for newer welders this is probably the hardest part of welding, so being able to concentrate on getting a good puddle going without nuking the material is helpful. Even if you do burn through your consumables faster.

    Its not ideal, but for learning it is invaluable.
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  17. #47
    Registered User Dimi's Avatar
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    Quote Originally Posted by takai View Post
    It is all well and good to just say increase travel speed, but for newer welders this is probably the hardest part of welding, so being able to concentrate on getting a good puddle going without nuking the material is helpful. Even if you do burn through your consumables faster.

    Its not ideal, but for learning it is invaluable.
    Of course it is hard, although i'm not sure xnke is early in learning curve?
    Just my opinion, if you genuinely want to become good at anything, you need direction.
    Nobody can point the finger at you and say, weld faster now and it magically happen. You can take useful information under your wing, keep it in mind and eventually it will happen. End of the day, we are all still learning in some way, you think if someone like shauns metal says hey Dim, you should try doing it like this instead because XYZ, i'm going to tell him my way is better? I might not adopt the method but i'll sure as shit give it a go.

  18. #48
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    Best way to increase travel speed in days past, was to practice filler feed through your fingers, when not actually welding - so basically becomes a muscle memory action.

    The OP's problem is possibly insufficient amps if there's not something contaminating. Assuming it's 1.6 rather than a metric 1.5mm wall, I'd probably go 80+ amps, get a near instant shiny weld pool, then tack in 3 or 4 spots. Restarts on the tacks might stop any oops moment, when the keyhole forms dab, probably using 2.4 rod to take some of the heat out. Don't know if there's variable amperage control available, but foot off the accelerator after a bit of travel is usually required - and back way off to avoid a finishing crater.

  19. #49
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    You aren't going to move fast enough to run on heavily oxidized high-shine 1mm thickness tubing or intercooler end tanks without fiddling with the balance. 1.5mm tubing, if it's that polished supershiny stuff, is STILL going to melt the base metal, before your arc can finish stripping away the refractory aluminum oxides from the surface-you're never going to see a shiny weld pool form up before the tubing just melts away. You can wirebrush all you want on some of that stuff-it just won't break the oxide layer until you break out the file, or play with the balance to rip off some of that surface oxide before you start putting heat in.

    On mill finish tubing, no problems. I've only ever had problems with the shiny polished stuff, a lot of the polishes use aluminum or cerium oxides as the abrasive to do the polishing, and they both embed into the aluminum and have MUCH higher melting points than the base metal. Some of the shiny ebay intercooler pipe kits, or sheet aluminum that's been polished on one side, always gives trouble.

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