Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / Inspection & Qualification / Direction of welding, does it matter?
- - By aevald (*****) Date 05-08-2009 04:32
Hello folks, there have been many occasions where this has come up in discussions of welding practices and procedures. Did a little demonstration for the folks in class this evening to give them some insight as to the differences that technique can make. The following picture was done with 1/4" A36 plate, .035 ER70S-6 wire, and tri-mix gas, machine set at approximately 25 volts and 380 or so ipm of wire speed. One side was welded with a forehand progression, the other side was welded with a backhand progression. You can see some obvious differences in the penetration characteristics exhibited by the two methods. There have been other examples of this on the forum in the past, I thought I'd just refresh this topic a bit. Best regards, Allan 
Parent - - By Lawrence (*****) Date 05-08-2009 05:40
Three star illustration.
Parent - - By dmilesdot (**) Date 05-08-2009 12:49
Here is what I have experienced with welders testing with FCAW.  I understand that your process was GMAW.  However: It is obvious that penetration is better (more) with the drag technique but the radiographs that I have seen all have trapped slag when using the drag technique.  When the same welders used the push technique most all would pass.  When I was welding with FCAW I wanted to see the leading edge of the puddle to know that the slag wasnt getting in front and then I was running over it.  I may be comparing apples to oranges (fcaw to gmaw).
Dave
Parent - By aevald (*****) Date 05-08-2009 14:06
Hello Dave, I follow where you are coming from, much earlier in my career I welded a lot with 1/16" FCAW shielded with CO2. This particular wire was a flat/horiz. only wire and we did indeed forehand it a considerable amount without appreciable problems. Having said that, I do believe that the advent of all-position wires and CO2/argon mixed shielding gases has brought about a need for a difference in technique; ie, backhand welding in a lot of cases. I also believe that the majority of CO2 shielded wires display different puddle characteristics with regard to penetration, they tend to have a slightly harsher arc and better digging characteristics. The CO2/argon shielded wires usually display a much softer arc and less penetrating arc characteristics. I also believe that operator technique and machine parameters can have a considerable effect on how the finished welds turn out.
     I am going to do some additional testing with both shielded and self-shielded FCAW wires, I'll be sure to include pictures of those as well. Thanks for the reply, Dave. Best regards, Allan
Parent - - By bozaktwo1 (***) Date 05-08-2009 13:06
Excellent photo, Allan.  I saved it for use in my own classes.  Where does the royalty check go? :)
Parent - - By js55 (*****) Date 05-08-2009 13:15
Would it be possible to cut the plate in half and view the mid weld cross section?
Parent - - By aevald (*****) Date 05-08-2009 13:55
Hello js55, I actually cut 1" off of each end of it, this end had the more dramatic difference, the other end wasn't quite so pronounced yet there was still a definite difference. If I get a bit of time today I'll section it in the middle and see what it looks like. Best regards, Allan
Parent - - By js55 (*****) Date 05-08-2009 14:21
Allan,
Your way ahead of me. It would be interesting to see it as it progressed. Was the start and stop at the same end for both?
Parent - By aevald (*****) Date 05-08-2009 14:55
Hello js55, yes, the starts and stops were at the same ends. Regards, Allan
Parent - By Shane Feder (****) Date 05-08-2009 14:00
Hello guys,
I have posted on this subject before because I absolutely hate (excessive) pushing with GMAW or FCAW.
There is nothing wrong with +/- 10 degrees of vertical, it is when the welder is too lazy to move his head to clearly see the arc and instead tilts his torch over even further past the 10 degrees and pushes the molten metal ahead of the arc. As everyone is well aware the arc must be able to contact the base metal to ensure sound fusion, if the puddle is too far ahead the arc is just burning onto the molten puddle and you will have a weld that looks acceptable on the surface with no fusion underneath.
In the early 90's I worked as a CWI / Radiographer in New Zealand and I would witness GMAW welder qualifications and then go back to the lab and radiograph them.
I could almost pick which ones would fail ( generally lack of inter run or lack of sidewall fusion) before I radiographed their coupons purely based on the angle of their torches during the actual test.
Regards,
Shane
Parent - By aevald (*****) Date 05-08-2009 23:14
Hello Curt, the royalty check would be a nice thought, but then the ORS(Obama Revenue Service) would just be hunting me down for their cut..... sorry I couldn't help myself. Best regards, Allan
Parent - - By PlasmaHead2 (***) Date 05-09-2009 17:30
Allan,
THANK YOU! You have finally put to picture something that I have been getting bashed on for years now.
One shop I worked at was all GMAW; .035 70s3 (it might have been s6), 75/25 Ar/co2 gas, and the voltages and wfs varied a lot because of the thicknesses (1/16 up to 3/8) and positions, but I was labeled a "drag queen" because everyone else pushed "because it penetrates better". The WPS's (if you could call them that...) left the subject wide open other than the 30* limit.
The shop closed not too long ago, so even though it doesn't matter anymore I still feel better, Thank you again :)

Just out of curiosity, when you say Tri Mix do you mean a mostly helium, argon, O2/CO2 mix?

Thanks again,
Clif
Parent - By aevald (*****) Date 05-09-2009 18:57
Hello Clif, we use gases supplied from Airgas. I don't know the exact mix of this particular one, however, I believe it is mostly argon, secondly CO2, and thirdly helium. My latest specification sheet from them lists three generic tri-mixes. I believe you can also request special mixes, for a price. Enjoy your weekend and best regards, Allan
Up Topic Welding Industry / Inspection & Qualification / Direction of welding, does it matter?

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill