4G Tig Aluminum

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Hello all had a question trying to do some welding valadations for a all position Tig aluminum 1/8" 6061 square butt with max 1/16" gap.  The WPS calls out for full penatration and no pulse.  I had no problems at all with the 2g and the 3g pretty easy.  Problem I'm having is with the overhead.  I get a nice looking weld with full penatration, but on the back side my penatration sinks due to gravity so it leaves what looks like undercut it is not flush or sticking up out of the aluminum.  I know its good all the way through but the CWI does not want the undercut.  I've tried playing around with different amps and I either don't get full penatration or I get the undercut on the backside like I described.  Any suggestions??  Really would like to get the valadated so we can start certing all position aluminum.Thanks
Reply:You could try turning the frequency up if your machine will allow you to do that, or you could try pulsing the current (either with a pulser or with a remote)One way or another you need to find a way to lower your overall heat input but still have a high enough amperage to get the penetration you want.  A chill/backer block might also be the answer if your procedure would allow for it.Another possibility would be to use a larger diameter wire and feed it with some force to influence the penetration profile and chiil the pool at the same time.Have we all gone mad?