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  1. #1
    Join Date
    Apr 2008
    Posts
    19

    Default How to properly preheat aluminum

    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

  2. #2
    Join Date
    Sep 2005
    Location
    northern NJ
    Posts
    1,847

    Default

    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.
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  3. #3
    Join Date
    Dec 2007
    Location
    southern California
    Posts
    1,783

    Default

    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.
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  4. #4
    Join Date
    Apr 2008
    Posts
    19

    Default

    Thanks guys

    I will give the ballance controll a try.

  5. #5
    Join Date
    Apr 2009
    Location
    KANSAS
    Posts
    511

    Default

    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.
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  6. #6
    Join Date
    Dec 2007
    Location
    southern B.C
    Posts
    51

    Default 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

  7. #7
    Join Date
    Feb 2007
    Location
    West Farmington, OH
    Posts
    746

    Default

    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?
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  8. #8
    Join Date
    Apr 2009
    Location
    Central Florida
    Posts
    197

    Default 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
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  9. #9
    Join Date
    Nov 2006
    Location
    Lake of the Ozarks MO
    Posts
    3,559

    Default

    Quote Originally Posted by pescaloco View Post
    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.

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  10. #10
    Join Date
    Oct 2007
    Posts
    2,949

    Default Ceriated

    Quote Originally Posted by Blondie_486 View Post
    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
    "Bonne journe'e mes amis"

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