To weave or not to weave???

By Lawrence (*****)

Date 09-24-2007 12:03

Whipping (forward and back) a spray transfer or Globular transfer GMA weld is not the best way to deposit metal.

Is it good enough? That is the real question.

The Whipping will cause inconsistant fusion in groove welds and lack of sidewall fusion in Fillets. Most often they are just piling weld metal on top of itself in order to increase the fillet size or to get a certain ripple in the cosmetic appearence... it has nothing to do at all with making a more sound weld.

When I get professional welders as students this is one of the habits I try to break in them.

Just make a 3/8 thick 70 degree included bevel test coupon with a backing strip. Weld one with straight stringers and one with a whip and see which will pass the guided bend.

A fillet break test will prolly be just as descriptive.

Now if a welder can whip his spray transfer mig gun and pass a destructive test....? I don't argue with succsess... However, I've never seen one pass.

Now Lots of folks in my neck of the woods run whipped spray transfer or even spray/Glob vertical down on heavy farm equipment. They don't break most of the time so they figure that is good enough... However when they begin to compete in the global market or for some other reason are asked to work to code qualified procedures they run into process control/training difficulties.

By aevald

Date 09-24-2007 13:56

Hello Lawrence, I would respectfully have a slightly different take on this. As far as the whipping goes, I would agree that "whipping" can have various interpretations and some of these methods could as you pointed out cause issues with weld performance. On the other hand, manipulation of the weld pool with gun movement in the same direction as the weld progression is not always problematic. I would point out that as the gun is brought back towards the weld pool this action can aid in filling the groove and washing metals out to the edges to aid in preventing undercut along the edges. Especially when making horizontal groove welds and fillet welds. I do believe that operator skill and technique is really the telling factor in this discussion. I have personally done this type of welding using both a manipulated gun movement and no movement at all other than the forward travel of the gun, both can be successfully employed. You always have very good information for all of the folks that receive answers from you, I would just differ slightly on this one. Best regards, Allan

By Lawrence (*****)

Date 09-24-2007 15:11

Hey Allan,

I was trying to be careful with my wording and knew I would get some dissent on this one.

Still... I think the best way to consistantly deposit a flat or horizontal fillet with GMAW Spray Transfer Mode is with a stedy forward progression with a push angle, keeping the the spray at the leading edge of the puddle. If the voltage, WFS and Gun angle is correct there will be no undercut or underfull issue with a straight consistant progression.

I've seen guys who can make ripples so pretty that I'm sure their Mom's would cry, way better than I'll ever be able to put down, Alot of the time they do it with 0.045 wire 400 ipm and 75/25 gas.. Yup all the edges are and toes are filled but I also know the *best* quality isn't there.. So I still don't think they will stack up mechanically or consistantly with a steady forward progression, proper parameters and correct gun angles.

Robots often move forward and then stop, allowing for side wall or toe fill, an excellent example of making cosmetic ripples and high quality, but it's pretty uncommon for them to move backward against the direction of travel in any weld that is going to require complete sidewall fusion.

Again I think we need to explore "exactly what is good enough" If the whipped welds are meeting quality criteria it's hard to say it's wrong. But I think when the criteria is based on destructive testing (AWS D1.1 for example), that whipping back against the direction of travel is going to produce inferior results and consistancy.

I'm expecting Al to pipe in and give us a couple of stories about being called in to qualify welders using these two different techniques.

By aevald

Date 09-24-2007 15:24

Hello Lawrence, as you said, interpretation of this method item can be construed in various ways. Certainly in any case, testing and performance of the weld will be the telling factor. I would welcome comment from any others on this topic, Al, Henry, where are you guys? Always willing to listen and learn. Thanks, Lawrence. Best regards, Allan

By jd369

Date 09-24-2007 15:39

I don't use a back motion, I generally will move forward and then pause for a half a second and then move on for the "whipping" motion on groove welds. I use this method for CWB testing on flat plate with a backing bar and for the fill and capping passes on open root groove joints for TSSA (ASME SECT VI) on flat plate with bend testing and have not had a failure yet. For fillet welds I will use a "J" motion for lack of a better term. I'll move forward in the corner and then whip up to the top plate to get the desired fillet weld size.
I find that bead sizes are much easier to maintain using a whipping motion as opposed to a consistant motion.
Regards
Jim

By ssbn727 (*****)

Date 09-24-2007 18:11 Edited 09-24-2007 18:14

Hi Allan!

I have to agree with Lawrence on this... When it comes to flux core, there's a correct technique to use when weaving is allowed, and there's an incorrect way also. In other words, always weave ahead of the solidified slag and never over it, otherwise you will end up with slag inclusions, and this should only be used in out of position deposits. There is no logical reason to weave in the flat or horizontal position so long as your wire placement is correct, your parameters are correct, and your travel speed is correct & consistent - period!

I remember one time, many moons ago - I was working for a company that were repairing and refitting the infamous Grumman buses... The first thing I noticed was the welders were as Larry phrased it, "Whipping" their GMAW spray deposits using .035 wire (I forgot the AWS classification, It was around 25 years ago!) in any position but noticably in the vertical up position!!!

The first thing I asked was why were'nt they using a GMAW -P otherwise known as a pulsed system instead, and I was told that their welders could pulse their welds manually... "Well something does'nt "Jive" here" was my response to the supervisor, and he told me straight out: "You either learn how to do it the way they want you to or else you do'nt stay on the job!!!"

At the time I was desparate for a job in the New York Metro area so I welded to their technique!!! Low and behold, they were running short of GTAW welders so they asked me if I had any experience with TIG... I said: "Does a bear crap in the woods???" They looked at me cross eyed for a second then followed by stating to me: "Son! If you can show us that you can TIG, we'll even give you your own machine, and you'll be doing most of the TIG repairs around here, and you'll also weld the stainless steel joints close, and personal to the gas tanks in the buses."

This is one of many stories I have that involves some parts of my start in welding, and because there are so many parts, it's one of the reasons why I have'nt as of yet contributed to your thread about how one started in welding... So I hope you can be patient, and wait just a little longer for me to contribute to that excellent thread.

I have more to talk about this particular job and yet, I do'nt have the time to complete it because, I have to get ready to travel to Houston tomorrow so, I'll have to end it here. When I get back, I'll finish it then. ;)

Respectfully,
Henry

By aevald

Date 09-24-2007 19:00

Hi Henry, I don't necessarily disagree with Larry's analogy on this topic, although I do have a slightly different take on it. Operator technique, along with correct parameters and shielding gases in conjunction with proper testing of finished results (visual, destructive, or non-invasive) will be the real determining point to this thread. The statement, "the end, justifies the means" is really the heart of this subject for me. I, like most of you(I believe), like a good debate to bring out the various issues tied to a particular subject. In this case I believe we have all had a good debate and I will come away from this better informed and educated in the various views that have been expressed. Many thanks to all. Best regards, Allan

By CHGuilford (****)

Date 09-24-2007 16:57

What I see as a potential problem is that weaving or whipping is often used to build up weld size in that pass and sometimes the weld "rolls over the slag". The bead surface and size may look good but underneath there may be problems. You can't see that without having Superman's x-ray vision but you often can see it when you make a cross section. Usually you don't need any macroetch chemicals to see the slag or void.
Even then, if you cut across one spot, it can look good, but move a fraction of an inch and you see a different story.

FCAW has more of a problem with this than GMAW does but I have seen some good looking welds that were incompletely fused to the faces and broke off easily.

I won't say weaving or whipping will always be a problem, but when I see a welder has had to do that, I like to check his/her technique to get a "comfort level". At the same time, a welder who is not whipping, but "holding the puddle back" to build size can also have the same problems.

(Then try telling the engineer/boss/owner that a pretty weld bead may have problems and that you need to grind into it to check it out.)

By aevald

Date 09-24-2007 17:45

Hello Chet, I do not opt to promote "whipping" with the FCAW processes, the main reason being that the formers in the fluxes tend to shape the weld bead to a great extent, this is not the case with the GMAW Spray process, you are somewhat at the mercy of gravity and surface tension to shape the bead. I completely agree when an individual uses various methods to increase bead size that it can lead to problems with weld performance, specifically cold-lap, also referred to as roll-over, and undercut also can result. The original post was inquiring about GMAW so I tried to stay with that specifically. Weld bead edge conditions such as undercut and cold-lap can generally be seen quite readily and would indicate, as you noted, that some excessive use of manipulation or travel speed applications are going on, or possibly some machine setting issues are having an influence. When considering GMAW Spray welding processes in production I try to stress proper wire diameter relative to material thicknesses, joint and groove configurations, cleanliness of materials to be welded. One should also consider positioning of the materials to be joined, are they flat welds, troughed welds for fillets, horizontal fillets, groove welds in flat or horizontal positions, all of these variables can have an impact on successses with GMAW Spray and possibly require different operator approach with regard to technique. Best regards, Allan

By timczx6 Date 09-25-2007 10:35

Wow! Thanks for all the comments.

By CHGuilford (****)

Date 09-25-2007 13:39

I agree, Allan, that it is best to consider the work to be performed and set machine parameters accordingly, to position work for flat/horizontal, to utilize joint configurations that will promote good welding.

My comment was intended to be general in nature; I only mentioned FCAW as a comparison - GMAW is certainly a "different animal".

At the same time, we understand that welders will try to compensate for less than optimal conditions by varying their technique. Sometimes that is OK and sometimes not so OK...and sometimes 'we' don't give the welders much choice in the matter. They often are forced to do the best they can with what they have.
But the real value in all of this is to bring out that there is no "one size fits all" solution. The best way to prevent problems is to better understand the hows and whys for the work at hand.

Good thread.

By aevald

Date 09-25-2007 13:54

Hello Chet, and good morning, at least where I am at. I do believe this has been a good thread, your mention of "one size doesn't fit all" certainly does apply, not only in these instances but in many others as well. I will certainly continue to look for the "eye opening threads" and learn immensely from them as well. Thanks for your input here. Best regards, Allan

By 1fastguy (**)

Date 09-25-2007 15:41

I agree with Larwence. I am not sure where this "whipping thing" comes from other than it seems to me the welders lack of training and there for do this to try and make there welds look better. I always have to retrain some welders to stop doing this and just run a straight pass. I always tell them if you take a role of dimes and knock them over that is what your welds should look like regardless if it is GMAW or GTAW. The biggest problem I see with this is the grain structure of the puddle as it tends to not overlap enough to give it stuctual integrity and there for makes a weaker weld. Just my 2 cents

By jd369

Date 09-25-2007 17:16

1fastguy
If you are just using a straight forward progession as Larwence has described then how are you getting the appearance of a stack of dimes knocked over in your weld bead when using the GMAW process? To get that ripple using spray transfer you will need to manipulate the arc using a whipping motion, circles or some sort of motion.
Jim

By 1fastguy (**)

Date 09-25-2007 18:11

Not at all move forward stop, move forward stop acieves the same result if you like. By moving straight forward with no weaving what you get is a bunch of very nicely stacked puddles on top of each other that are structualy very strong.

By jd369

Date 09-25-2007 18:38

I agree, that is what I do as well, move forward and stop. I believe Lawrence was describing a steady forward progression which wouldn't allow for any ripple.