How to properly preheat aluminum

[pescaloco]

Hey guys question for you.

I made a set of steps out of .250 aluminum angle and had some troubles.

I have a 250amp water cooled torch tig set up. I was using 200 to 220 amps 50/50 ballance AC high freq. It seemed to take forever to develop a puddle and the pace of the welding was so slow that I had some real problems with warping and distortion.

Even after getting what looked to be a good flowing weld that was slightly concave in bead profile, the penetration seemed to be pretty poor. Ok for a set of steps but not anything I would trust that would be subject to load or vibration cycling.

What is a good way to preheat to help the weld penetration and hopefully controll distortion from excessive sustained localized heat input.

Thanks

[MMW]

If you want to pre-heat you can use a torch or a heat gun. Get yourself an IR thermometer or a temp stick & heat to about 350-400. Only pre-heat one section at a time as aluminum transfers heat quickly so it will cool off if you try to heat to big an area at once. Don't know what tig setup you have but if you have a peddle or finger control up your amps on the machine so you can get more heat at the start & then back off as needed while welding. If the metal is clean you can change your balance to about 30-70 for more penetration.

[Desertrider33]

I agree your main problem is the 50/50 balance setting. You have too much time in the cleaning portion of the cycle and that's why the machine feels under powered and is taking forever to weld. I normally use 30% cleaning.

[pescaloco]

Thanks guys

I will give the ballance controll a try.

[Rig Hand]

Don't know your machine but my syncrowave has three different starts 1,2,&3. One is a slow, cool start. Three is almost like a hot start. Check your owners manual. You can also max out your machine and floor the pedal to start the puddle.

[journeyman]

preheat alum

You definetly have enough "jam" with that amperage.Infact your at the top end of that pure tung, this could be causing grain growth, which is greatly restricting for power transfer. I think from experience that if you switch your tungsten from pure to ceriated you might be suprised.
It has a lower work function which means you will require less power from your machine to put out the same amps as pure. Also, it arc starts easier, has a more stable arc and the addition of the ceriated oxide works as a emission enhancer and grain growth inhibitor. You might also consider going to a 5/32 tung as this is a more appropriate tung size for your application.

Good luck

[Blondie_486]

Where are y'all getting Ceriated tungsten? Most of the local welding stores in my area only carry pure and 2% Thoriated, a few will have 1% Thoriated. Are you getting it mail order or what?

[andyman]

preheating solid AL rod

little off topic
but a guy at my work says you can preheat aluminum rod in the microwave. unlike aluminum foil it has fewer contact points so it wont start sparking and what not.

anyone know if this is true? or have an old microwave to test it

[FusionKing]

Hey guys question for you.

I made a set of steps out of .250 aluminum angle and had some troubles.

I have a 250amp water cooled torch tig set up. I was using 200 to 220 amps 50/50 ballance AC high freq. It seemed to take forever to develop a puddle and the pace of the welding was so slow that I had some real problems with warping and distortion.

Even after getting what looked to be a good flowing weld that was slightly concave in bead profile, the penetration seemed to be pretty poor. Ok for a set of steps but not anything I would trust that would be subject to load or vibration cycling.

What is a good way to preheat to help the weld penetration and hopefully controll distortion from excessive sustained localized heat input.

Thanks

I would say that there could be several other reasons for your problems you mention here and would also say without pics we are only blowing smoke.
I and others here have used machines that have nothing but 50/50 balance forever and I highly doubt that would ever cause any problem. I have had excellent results with those machines ...don't jump to that conclusion. That would be distortion!
Way too much speculation here without seeing IMO.

[davedarragh]

Ceriated

Where are y'all getting Ceriated tungsten? Most of the local welding stores in my area only carry pure and 2% Thoriated, a few will have 1% Thoriated. Are you getting it mail order or what?

It's very common out here in the West. 2% Ceriated (orange stripe) or Lanthanated (gold stripe) are generally kept in stock locally.

If you can't find any in your part of the world, www.Arc-Zone.com has any flavor you want.

Dave

[Blondie_486]

It's very common out here in the West. 2% Ceriated (orange stripe) or Lanthanated (gold stripe) are generally kept in stock locally.

If you can't find any in your part of the world, www.Arc-Zone.com has any flavor you want.

Dave

Thanks Dave,

Out east we can only get pure or thoriated tungsten. I guess I'll have to order a box of ceriated and give them a try. I've always thought there had to be something other than pure to use. It works and I haven't had any failures on any of my aluminum work and have people bring stuff from 2 hours away just to have me weld it, but I've always thought there might be something better out there.

[FusionKing]

Ask for some of the Gold as well. I think it is tuffer. There is also rare-earth now at several places and people who use it swear by it.
That will be my next choice as Air gas now offers it.

[gordfraser]

To the OP question.

i would say without seeing any pics that it sounds like you are not getting a puddle going quick enough so you are just putting more heat than should be required.

if the balance adjustment doesnt sort it then up the amps a little.

i have an inverter and a fillet joint on 1/4" alu. can take 230A with 20% cleaning and 80% welding balance when everything is cold.

What tung were you using anyway. I never saw where you mentioned it.

[Frank Motoweld]

Good tungsten!

Ask for some of the Gold as well. I think it is tuffer. There is also rare-earth now at several places and people who use it swear by it.
That will be my next choice as Air gas now offers it.

Hi FK,i have a few 1/16 rare earth and they work quite well,Frank