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Old 06-28-2017, 09:15 AM
billfunk29 billfunk29 is offline
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Default DC TIG on aluminum

Years ago a friend showed me how his Thermal arc inverter could weld aluminum with DC. With an inverter the DC is more like Square wave AC. I recall that it worked well. Anyone else doing this?
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Old 06-28-2017, 10:58 AM
lots2learn lots2learn is offline
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I don't think their is any difference on DC between an inverter and transformer machine. Heliarc was the original Gas Tungsten Arc Welding for Aluminum. It used helium and DC. The Saturn V aluminum parts where welded with DC. Also tube mills have used DC for high speed welding of seamed tubing.

DC produces welds with less porosity than AC but cleanliness is more important. Also a much narrower bead.
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Old 06-28-2017, 11:30 AM
toreadorxlt toreadorxlt is offline
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DCEP or DCEN?
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Old 06-28-2017, 11:38 AM
lots2learn lots2learn is offline
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DCEN, On DCEP the Tungsten cannot handle many amps. around 10 or 15% of DCEN capacity.
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Old 06-28-2017, 03:32 PM
crystallographic crystallographic is offline
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Quote:
Originally Posted by billfunk29 View Post
Years ago a friend showed me how his Thermal arc inverter could weld aluminum with DC. With an inverter the DC is more like Square wave AC. I recall that it worked well. Anyone else doing this?
Guys welding heavy (3/8") sections routinely use DC, either TIG or MIG.
DC very common when using 100++ amps .....
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Old 06-29-2017, 08:28 AM
billfunk29 billfunk29 is offline
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Default DC tig

DCEP with a big tungsten and water cooled torch. No cleaning action with DCEN.
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Old 06-29-2017, 11:11 AM
lots2learn lots2learn is offline
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Originally Posted by billfunk29 View Post
DCEP with a big tungsten and water cooled torch. No cleaning action with DCEN.
I really doubt my 300 amp water cooled torch could weld .063 Aluminum with 1/8" tungsten(largest torch can use) on DCEP. Almost all DC Aluminum using helium is DCEN. Even if it works I dont know why I would want a wider bead and less penetration than AC. Seems AC with balance set more to cleaning would be a better option?
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Old 06-29-2017, 03:16 PM
billfunk29 billfunk29 is offline
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Default DC tig on Al

Reason I brought this up is: I got a smoken deal on a Maxstar 200LX. NIce machine, but no AC. I wanted something more portable than my Sychrowave, but I also wanted to do aluminum.

IN my quest I found just what I was looking for. This should be fine for the tacking I do before OA finish on body panels.

https://www.youtube.com/watch?v=CHkx8cca-SQ
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Old 06-30-2017, 08:30 AM
billfunk29 billfunk29 is offline
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Default Inverter DC

I am not an electrical engineer, but this is how I understand the inverter DC. The argon can only turn into plasma with higher voltage. Hence the need for High Frequency arc stabilization on AC transformer. The time at or near zero volts is longer with transformer AC. Lots of short pulses in an inverter will behave differently and allow alternate methods.
inverter.jpg
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Old 06-30-2017, 10:48 AM
crystallographic crystallographic is offline
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Originally Posted by billfunk29 View Post
I am not an electrical engineer, but this is how I understand the inverter DC. The argon can only turn into plasma with higher voltage. Hence the need for High Frequency arc stabilization on AC transformer. The time at or near zero volts is longer with transformer AC. Lots of short pulses in an inverter will behave differently and allow alternate methods.
Attachment 42246
Hmmm....
Bill, your "transformer DC" graphic looks exactly like what is used for "DC generator" illustration .... so does this mean that DC transformer is exactly as flat as DC generator?
(I use a 200A motor-generator unit for my stick welding on aluminum .... )
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