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Question on Arc Initiation

Posted: Mon Dec 29, 2014 6:03 pm
by SmartDave
When welding on Aluminum (or I guess any metal) is it better to floor the petal to get a puddle quickly or to slowly approach the heat to liquefy the metal?

Re: Question on Arc Initiation

Posted: Mon Dec 29, 2014 6:23 pm
by Braehill
Dave,
Most times it better to get it hot enough to puddle in the first few seconds and get moving. I would have to think if there's anything that I would advise doing the opposite, maybe others might chime in with something. So to answer your question, yes mash the pedal and get the puddle going and back off as needed while you progress. Aluminum especially will run out of places for the heat to go as you get to the end of your weld and need a lot less heat input. You'll have to learn to gauge this by your bead profile, it will start to flatten and get wider, as well as sometimes get dull.

Len

Re: Question on Arc Initiation

Posted: Mon Dec 29, 2014 6:25 pm
by Oscar
neither and both. :D

The problem is that you cannot generalize one procedure to cover "any metal", because metals react differently to heat input, it's called thermal conductivity.

Which metal exactly are you trying to weld, in what thickness, overall size, joint configuration? Answer those 4 aspects and you can get a much better recommendation as to how to approach the situation from some very knowledgeable people here. :)

Re: Question on Arc Initiation

Posted: Mon Dec 29, 2014 6:32 pm
by SmartDave
So specifically I am laying beads on 6061-t6 1/8 aluminum. I up until this point had been slowly approaching the puddle. But the last few beads I did, I just mashed the pedal (135 max amps) and it puddled quickly and just "felt" better. I have been practicing tapering off on the power as I am moving along in the bead to make sure it does not flatten out and stays a consistent height and width (well trying anyways :-) )

Thanks for the quick replies

Appreciate the feedback

Re: Question on Arc Initiation

Posted: Mon Dec 29, 2014 7:03 pm
by Oscar
In that case, yes you do need more initial amperage when doing aluminum. Ideally you want the puddle to form clear and shiny like a tiny mirror in 3sec or less. With practice you can get it form nearly instantaneously, and then back off as you add filler as you move down along the joint. Evaluate each test piece carefully and note the bead width to see if you are backing off correctly on the amperage as you scoot on down, and remember to use cool test pieces not the same tiny ones over and over again---the heat soak changes things dramatically so you'll get nowhere fast.

Re: Question on Arc Initiation

Posted: Mon Dec 29, 2014 7:26 pm
by SmartDave
Thanks all for your replies. I must say I am having a blast with this new Tig machine of mine. I even got bored of my small pieces today and tried to lay a bead on my aluminum ladder :-) just to try something different.

Re: Question on Arc Initiation

Posted: Mon Dec 29, 2014 10:08 pm
by weldin mike 27
Hoping its your broken, un usable, ever again ladder.

Re: Question on Arc Initiation

Posted: Mon Dec 29, 2014 10:53 pm
by SmartDave
No way, it's my new and improved ladder. It should be stronger now with that added aluminum :-)


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Re: Question on Arc Initiation

Posted: Mon Dec 29, 2014 10:59 pm
by weldin mike 27
Quick release ladder....saves time getting you to the floor

Re: Question on Arc Initiation

Posted: Tue Dec 30, 2014 12:45 am
by Rick_H
weldin mike 27 wrote:Quick release ladder....saves time getting you to the floor

Made me chuckle...

Dave, what Mike is getting to, is you are not supposed to repair, weld or modify a ladder...if they get damaged in any way, they should be tossed.

Re: Question on Arc Initiation

Posted: Tue Dec 30, 2014 3:16 am
by weldin mike 27
Unless you are a very confident welder, and are sure of the grade of alum. If the ladder isn't welded at all, ie, bolted or swaged/ crimped is is possibly an unweldable grade of alum.

Re: Question on Arc Initiation

Posted: Tue Dec 30, 2014 4:26 pm
by SmartDave
Understood. This is just a cheapy 4 foot ladder that I can jump off of from the top, but point taken.


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Re: Question on Arc Initiation

Posted: Tue Dec 30, 2014 4:48 pm
by weldin mike 27
Good to hear.

Re: Question on Arc Initiation

Posted: Tue Dec 30, 2014 8:29 pm
by zank
I am light footed. On aluminum, I generally light up on the low end, let the cleaning action do its thing, and then bring the heat up to get a puddle. If I jam too quickly, those surface oxides like to float in my puddle. Little buggers.

On steel, SS, and ti, I step on it a little quicker. Especially on tacks. If I heat up too slowly, the two pieces don't fuse and I get a bigger tack than I want because I have to add rod.

Re: Question on Arc Initiation

Posted: Tue Dec 30, 2014 8:31 pm
by SmartDave
Thanks for the feedback