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Up Topic Welding Industry / General Welding Discussion / How is MCAW classified as far as inspection is concerned?
- - By dschlotz (***) Date 07-10-2015 11:26
I have another question about metal core. I just went to a demo of the Miller Pipe Worx 400 at Shasta College in California and got to run some metal core wire. Sweet! Know body there could give me a clue as to how it would be classified as far as GMAW, FCAW, MCAW. There were all ASME guys. I know that MCAW is new to me and now that it is being used more as semiautomatic, I need to know how to inspect this process as far as the paper work. If it is classified as GMAW then it would have the same requirements as far as prequalification is concerned. Am I on the right track?

Dennis
Parent - By SCOTTN (***) Date 07-10-2015 15:20
See if this forum link helps...

https://app.aws.org/forum/topic_show.pl?tid=13380
Parent - - By welderbrent (*****) Date 07-10-2015 23:23
I thought I saw where AWS came out with something even more official on it's classification and it did get included as GMAW.

Having said that, it has a flux core.  :confused:  So why?  There were explanations given which I don't remember.  I'll try to find out where I saw the info.  Might have been an article in the 'Welding Journal'.  Don't know.

He Is In Control, Have a Great Day,  Brent
Parent - By aevald (*****) Date 07-11-2015 06:55
Hello Brent, I don't believe that it has a "flux core" so much as it has a "powdered metal core". I recall this as being a plus from a number of standpoints: easier to change the metallurgical make-up of the wire to address different as-welded requirements and also easier to take it from a solid state to a liquid one (less arc energy). Best regards, Allan
Parent - - By ssbn727 (*****) Date 07-11-2015 07:01 Edited 07-11-2015 16:29
Ummmm,

Can someone explain to me how a "Metal Core" electrode filler metal can have a "Flux Core in the middle or center of it's core?" when the core of the wire/filler is made out Metal? Now the ASME does look at these welding processes differently than the AWS which just adds to the confusion but then again, what do you expect coming from ASME? Edit : 7/11/2015 12: 28 pm.

Respectfully,
Henry
Parent - - By aevald (*****) Date 07-11-2015 07:22
Hello Henry, glad to see a post from you. It came to me just recently that I hadn't seen anything from you for a while, I hope that all is well! Best regards, Allan
Parent - By ssbn727 (*****) Date 07-11-2015 16:56
Hi Allan and Al and Brent, Lawrence and the rest of the gang! Hi Kent! Are you still taking the Lactulose?:eek::lol::grin::twisted::wink::yell::grin::cool:

Yeah it's been a bit... I just got discharged from another pleasant stay @ my least favorite place to to visit - my hospital, and I say my with the fact that with all of the money these fine folks have been paid by my government insurers have virtually bought me a wing since I started this relationship with UPMC many moons ago even though it's really the taxpayer's hospital in the long run...

This time I needed to get topped of with 4 units of O Positive for starters and have them do a cardio catheter to make sure the tricuspid valve wasn't leaking like a sivv so they could repair it if necessary... Turned out that the valve was just fluttering a little more than usual and got much better once my supply of blood was stabilzed with the transfusions...

Meanwhile, one of my pesky Kidneys(WE all usually are born with 2) which just decided out of the blue and black now that I'm trying to visually articulate/describe, to announce it's presence and demand more serious attention from everyone involved in my overall health...

I call it my spoiled kidney because it gets so much attention and then makes more noise once it notices that other parts of my body are receiving the same if not more attention than itself1:eek::grin::roll::wink:

My Creatnine went way up to 3.0 because of this Kidney and the BUN (Blood Urea Nitrogen) went up 6 times the normal amount with both causing the oxygen in my blood to go haywire thus causing serious breathing problems also...

Well needless to say, al of theses conditions caused my body to go crazy and I eventually passed out and had to be life flighted again to the hospital in an eggbeater again... Ended up in ICU for a week and then to a regular room for another until they discharged me yesterday... So I got some reading to catch up on in here and elsewhere...:grin::cool:

Anywho, always a pleasure Allan! I'm gonna catch a nap buddy so I'll talk to you all later as soon as I get over being as sore as I am from all of the tests... Sure is good to be back home again!!!:eek::grin::lol::yell::wink::cool:

Respectfully,
Henry
Parent - - By welderbrent (*****) Date 07-11-2015 23:00
Good to 'see' you Henry.

My point would be that 'FLUX' comes in many variations, compositions, and applications.  It is only distinguished by it's content so as to produce the desired function.  Just as our stick electrodes have so many different compositions, so does the 'flux' in wire electrodes. 

Now, I understand where both you and Allan are coming from, the question really is how the manufacturer's, classification experts, and engineers see it. 

There are many things that distinguish the process we are using.  Can we look only at the question of if it produces slag or not to determine if it is a FCAW or a GMAW?  Not casting stones as I say this, that seems a little simplistic to me.

What is it's purpose?  Does it perform ANY of the functions of flux in other wire electrodes or stick electrodes? 

If it's only function were to provide faster fill then why not just use a larger solid wire?  Utilizing spray transfer to a higher production rate. 

These are questions and observations for me personally, not meant to cast doubt or stones at anyone.  I used metal core for a couple of weeks back in the early 90's but the test data on it at that time did not meet our specifications for the work we were doing.  So it got dropped and we stuck with the GMAW and FCAW that had been our tried and true up until that point in time. 

He Is In Control, Have a Great Day,  Brent
Parent - By aevald (*****) Date 07-11-2015 23:37
Hello Brent, I've been known to shoot from the hip from time to time and this is likely no exception. I "visualize" some of this in this fashion: I've got two metal lengths of tube, one of them is filled with solid wax that has been poured in and allowed to solidify, the other tube is filled with ground-up wax. If I take 2 heat sources of the same output and subject these 2 tubes to heat for the same length of time it is likely that I will see more melted wax coming from the one that is not solid. I would agree that this scenario would support the belief that for the same amount of deposited weld metal you would need more linear inches of the tubular powdered metal-filled wire and a higher wire speed at the same level of arc energy.

I believe that there is a certain amount of parallel between this and the conversation describing a solid wire vs. a tubular wire filled with powdered metal. If I also recall correctly from some of my followings and reading on this site and others, there is a component of this discussion that covers cross-sectional density and how the voltage/amperage efficiency is more efficient or better for a tubular wire filled with powdered metal. The end result being that deposition for a given scenario "can" be increased over a solid wire option.

Regardless of any of my views, I am always learning when I read the responses and posts on all of the great topics of this site. Best regards, Allan
Parent - By kcd616 (***) Date 07-11-2015 05:15
Dennis,
both Allan and Blaster
are in that neck of the woods
I have put out a call
to the people I know @ Miller, Lincoln, Fornius, etc, etc, etc
will see if they can help
this does interest me
but also Al Moore and Lawrence are the best you can get for info
just my thoughts
sincerely,
Kent
edit
forgot my very good friend Henry
Parent - By UpWeld Date 11-24-2018 05:58
Here you can read What is MCAW Welding? https://upweld.org/what-is-mcaw-welding/ i think its helpful for you
- - By 803056 (*****) Date 07-11-2015 15:14 Edited 07-11-2015 23:39
Interesting topic. ASME throws metal core into the category of GMAW, but they include FCAW with GMAW when it comes to qualifying the welder. The two are differentiated when it comes to qualifying the WPS by the electrode product form, i.e., solid electrode or metal cored electrode, versus tubular electrode.

One way to differentiate between the two is by whether or not there is a slag on the surface of the completed weld bead. Solid wire does not produce a slag layer. The silicon oxide islands scattered here an there are not considered to be slag. Flux cored electrodes, without a doubt, have a slag layer that must be removed from each welded bead (contrary to the belief that a multipass flux cored electrode does not require the slag to be removed from the completed weld bead).

Metal core; does it have a slag layer or doesn't it? That is the question? In the past, metal cored electrodes were included in AWS A5.18, but that is changing. It is my understanding it is now included in the same specification as flux cored electrode.

If the water wasn't muddy enough, they just stirred it up with a long stick.

Best regards - Al
Parent - By Northweldor (***) Date 07-12-2015 11:41 Edited 07-12-2015 11:45
I found this article fairly unbiased, considering it comes from a rod manufacturer presumably eager to promote the next must-have product! Claims little to no slag.

http://www.esabna.com/us/en/education/blog/advantages-and-disadvantages-of-metal-cored-wires.cfm
Parent - By 46.00 (****) Date 07-13-2015 06:43
Nice too see you back Henry, Intresting subject and potentially an explosive one!
Parent - - By Lawrence (*****) Date 07-13-2015 12:02
Ok,

MCAW  (Metal Cored Arc Welding) Electrodes have since 2012 been covered in AWS A5.36 Specification for Carbon and Low-Alloy Steel Flux Cored Electrodes for Flux Cored Arc Welding and Metal Cored Electrodes for Gas Metal Arc Welding

We can talk all day about percentages of slag in the weld deposit and that is fine... But as far as specifications and what they mean.. Here is what A5.36 says in it's statement of Scope:

1. Scope
"1.1 This specification prescribes requirements for the classification of carbon and low-alloy steel flux cored electrodes for flux cored arc welding (FCAW), either with or without shielding gas, and carbon and low-alloy steel metal cored electrodes for gas metal arc welding (GMAW)..."
    [emphasis mine]

The new specification supersedes A5.18 and A5.28

The 2015 D1.1 code should recognize this change in Table 3.1 etc.

So the moral of the story is:   MCAW is a GMAW process.   MCAW electrodes for plain carbon steels in the AWS world are specified in A5.36 with other cored electrodes, such as FCAW which AWS views as it's own process.

A3.0 Standard welding terms defines Metal Core thusly :
"metal cored electrode. A composite tubular filler metal
electrode consisting of a metal sheath and a core of
various powdered materials, producing no more than
slag islands on the face of a weld bead."
Parent - By welderbrent (*****) Date 07-13-2015 23:22
Thank you Lawrence.

That sounds like a pretty official conclusion to the matter.

May have been where I saw it previously, here on the forum from Lawrence.

He Is In Control, Have a Great Day,  Brent
- By dick (**) Date 07-14-2015 04:51
Dennis, said it best, sweet. We are now welding with MC6 (E70C-6MH4) semi on long seams and it tolerates contaminants great. Not really any more silicon deposites on surface than any other GMAW prcesses, crank it up and go.
Good info everyone
Thanks
Dick
Up Topic Welding Industry / General Welding Discussion / How is MCAW classified as far as inspection is concerned?

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