GMAW Correct gun angle (HELP please)

By Lawrence (*****)

Date 09-26-2005 15:30

Rules of thumb:

"Structural welding" can mean almost anything... It's a very relative term. A structure may be thick or thin, each requiring a different technique.

1) In spray transfer welding a push angle is used. The Hobart School of Welding in their "GAS Metal Arc Welding Basic" manual suggest a 5-10 degree push travel angle. I agree.

2) In short circuiting transfer mode a 5-10 degree drag travel angle will produce greater penetration while a 5-10 degree push travel angle will reduce penetration.. The push travel is generally used on thin sheet metal where burn thru becomes a problem. The drag travel angle is used for all other work due to its deeper, more consistant penetration.

By FSmalley (**)

Date 09-26-2005 16:58

I remember from school (85-86) we were taught to push the weld with a 10deg. torch angle. I think we were "spray Arcing". Does anyone think adversly to this ? If not then i will take this to be the unwritten rule.

By CHGuilford (****)

Date 09-26-2005 16:36

I don't do much with GMAW, mostly FCAW; so I won't presume to tell you that push or drag is best. I only want to suggest that you run some simple tee tests to decide for yourself which is best for your applications. Those are quick and cheap tests to do.

Chet Guilford

By swnorris (****)

Date 09-26-2005 18:45

Lincoln Electric's Gas Metal Arc Welding Guide recommends a slight push angle of 5 to 10 degrees for GMAW spray transfer.
Since you mention structural application in your post, I'm not sure if short circuit transfer is an option because it is generally not permitted due to the lack of penetration.
I think the most common with FCAW is a backhand or drag technique. This method allows for more penetration, as the arc force holds back the molten puddle. The backhand technique also helps the slag system to provide more consistent coverage on the weld bead. An angle of 10 to 20 degrees off center is sufficient for a consistent bead with good penetration. The forehand or push method is another technique. This can be a more comfortable method if you also weld with GMAW. The forehand technique creates a nice bead profile that is flat to slightly concave. Again, 10 to 20 degrees is sufficient to provide a consistent looking weld.

By jon20013 (*****)

Date 09-26-2005 19:07

I'm in general agreement with the technique recommendations here. We do nothing but GTAW and GMAW-Spray, the techniques mentioned for GMAW are the same ones we use here. When I was a young pup, maybe 30 years ago, I learned to GMAW weld using the drag technique, it was a hard habit to break but virtually every "expert" I've spoken to recommends the push technique, for a variety of reasons.

By Shane Feder (****)

Date 09-26-2005 22:10

FSmalley,
Agree totally with previous postings.
I have qualified numerous GMAW/FCAW procedures over the years and they were always performed with the torch angle at +/- 10 degrees from vertical for flat/downhand welding.
The biggest problem I found was the welders on the shop floor would change the torch angle to suit themselves and this would lead to varying depths of penetration/fusion. With the torch held out in front of them at +/- 10 degrees some of them were finding it difficult to view the arc so instead of changing the head/body position to suit they were just leaning the torch over to get a better view of the arc.This sometimes resulted in lack of inter-run fusion when they were pushing as the molten puddle was being pushed in front of the arc.
As I was in these workshops solely as an independant inspector I could only pass advice on to the foreman, what happened after I walked out the door I have no idea,
Regards,
Shane Feder

By FSmalley (**)

Date 09-27-2005 11:40

Thank you guys very much !!!

By cfrancis (**)

Date 09-29-2005 17:50

The push angle works great for spray transfer. One needs to be careful of the parameters used. Be wary if you are " pushing" too much of your molten out in front of your arc. That will fusion issues and defects such as coldlap, overlap etc...
You need to have a smooth sounding arc with some "crackle".

A drag angle "can" cause some un-desirable defects as well as poor aestetics to your welds.