Wire Size and Wire Feed Speed

"An epiphenomenon (plural: epiphenomena) is a secondary phenomenon that occurs alongside or in parallel to a primary phenomenon."

I had to look that one up.  Learned more than one thing today.  Now if I can use it in a proper sentence??

He Is In Control, Have a Great Day,  Brent

By js55 Date 06-04-2014 18:49

brent,
I actually should have used the singular and not the plural. So I learned something too.

By js55 Date 06-04-2014 19:31

Lawrence,
Its just a fiancy way of sayin essentially preheating.
Current squared times resistance. Ohms law stuff.
And as you can see, with resistance being reduced in bigger wires, it would be higher for smaller wires at a given I.
Not professing to be an expert (I shore ain't no eelektrik enjuneer) but I 've seen it, used it, and there is a great deal of literature available online.
Lincoln did the first work on this back in the 50's, and is the basis for all electrode extension technology today.
The I2R portion would be the part of the total energy to melt for which this phenomenon is responsible.

By js55 Date 06-04-2014 19:37

For whoever has Lincoln's black book. Take a look at the burn off rate or dep tables. You will see it is columnized by electrical stickout.
This is the I2R effect.

Interesting.  Need more time to look at it thouroughly.

He Is In Control, Have a Great Day,  Brent

Just to briefly add to what js55 did state in terms of RI^2.

This expression is regularly used as when it comes to computing electrical power 'P', representing the product of voltage 'U' and current 'I' and applying direct current.

Ohm's law postulates:

U = R*I

where 'R' is electrical resistance.

Because P = U*I and U = R*I,

we can write:

P = R*I*I = R*I^2.

This says (simply put) that the electrical power increases proportional to the square of current; i.e. doubling the current, quadruples the power.

In other words the current is a "nicely important" parameter, especially as it comes to arc welding processes.

In turn, and for 'completion' in terms of voltage.

Because P = U*I and

I = U/R

we can write:

P = U^2/R

That is. Power rises proportionally to the voltage squared, or; doubling the voltage quadruples the power.

Increasing the contact tube to work distance drops the current by increasing the electrical resistance across the increased wire extension. This again preheats the electrode extension which can be used to beneficially affect the 'burn-off rate' [m/min], which I may suggest as the wire virtually consumed. That is. The higher the resistance heating, the higher the burn-off rate.

As js55 said. This effect "...is the basis for all electrode extension technology today.", but also btw for e.g GTA hot-wire welding which on the one hand positively affects deposition rate and beneficially affects/reduces dilution by allowing the reduction of weld current.

Regards.

"That is. Power rises proportionally to the voltage squared, or; doubling the voltage quadruples the power."

Another interesting comparison and application.  And, it is interesting how many things fall into that ratio: doubling=quadruples.  Things like, double the diameter of a pipe and quadruple the volume if memory serves me right (I will probably regret not taking time to look some of these up).  And, double the speed at which travelling on the tractor and quadruple the probability of tip over if you take the curve at that speed.  And I recently had another one pop up that remember commenting about, I think talking with my wife about something, but I can't remember what it was.

Anyway, just thought it interesting how that ratio comes into play so often.

He Is In Control, Have a Great Day,  Brent

Thank you, Sir.
"Anyway, just thought it interesting how that ratio comes into play so often."
Yes, and of course: Happy Birthday and may God bless you.

Regards.

Thank you, and He has, does, and will continue.  I just need to stop complaining so much and count my blessings, They Are Many.

He Is In Control, Have a Great Day,  Brent

By js55 Date 06-05-2014 11:49

electrode,
I think perhaps you have a better grasp of it than I.
Good stuff.

js,
as usual all this follows an "intricacy e-function" the deeper one digs.
Thank you though.
But basically the effect described by yourself can maybe be summarised as:

- Proportional to current.
- Proportional to wire electrode extension.
- Proportional to wire electrode resistivity.
- Inversely proportional to wire electrode cross section.

Regards.

By aevald Date 06-06-2014 00:07 Edited 06-06-2014 00:56

Hello electrode and others, I have "briefly" gone through many of the replies to this thread. Now I have a question, what would be the group's take on metal-cored wires and how they might factor into this equation. I am asking this mainly because I have been led to believe that for a given weight of wire, weight being the equalizing factor, that the metal-core requires less "energy/current" to melt a similar quantity/weight of wire and thus efficiency would improve and deposition also. What might be the consensus here? Guess I am looking for more information and some discussion. Thanks and best regards, Allan

By kcd616 Date 06-06-2014 00:49

Allan
sounds like an in shop job, as opposed to field work
and I will take the metal cored
but like I said need more info if I was doing this
it is business and money choice, not really welding decision per say
only imho
Kent

By aevald Date 06-06-2014 00:58

Thanks Kent, I always look forward to some of these discussions where they get pretty in-depth. As you said though, sometimes details are where the real applicable responses lie. Hope your health is improving and you're feeling better. Best regards, Allan

By js55 Date 06-06-2014 12:04

Allan,
In the context of I2R heating metal cored will increase deposition over solids, and for the same reason as smaller wires. However flux core is even better (because the flux does not conduct) and can be welded in position as metal core cannot.

By aevald Date 06-06-2014 14:24

Definitely true for out of position work as far as deposition, yet, slag is a contender with regard to removal and clean-up, or possibly entrapment for those who are marginal in their welding skills. So I suppose that is a bit of a rub in the overall scheme of things and again, is the work shop or field? Thanks for your take. Best regards, Allan

By js55 Date 06-06-2014 14:51

Allan,
You know I have always heard a lot about the clean up issue with flux cored.
When I was welding it took me less than 5 minutes at the end of my shift to sweep up the flux. And I was going to sweep my bay anyhow.

By aevald Date 06-06-2014 15:00

I only mention flux in a "very" overall sense with regard to chipping/brushing and cleaning of that sort, particularly on multi-pass applications. When there are a lot of welders doing all of that it could be argued that it does take away from weld lay-down time. If a person wished to nit-pick it a bit more you might consider that spatter "could" be greater for the FCAW process than that of the MCAW spray. Here again, not always though if parameters are correct for both processes. Best regards, Allan

By Lawrence Date 06-06-2014 15:38 Edited 06-06-2014 15:42

The only advantage I see to MCAW over solid wire is the possibility of the current density being leveraged to produce smaller engineered weld sizes, which would increase cycle time and weld volume reductions that *might* justify the cost.   But this virtue of MCAW is rarely the reasoning behind the expense of the process change.   Typically MCAW is sold on the grounds of reduced spatter and fume.

This whole MCAW makes spatter free welds bologina has got to be stopped.     This is a parlor trick performed by salesmen in plants that have no process control    It's the same trick that gas salesmen perform with 3 part GMAW gas mixes for steel...(Stargon etc.)

They walk into a plant that has no process control, set up a shiny new peiece of equipment, or a new filler electrode, or a new shield gas, or an anti-spatter spray... And they *CORRECTLY SET WELDING PARAMETERS* and make a spatter free weld with the new gadget Dijour....

The salesman could have made the same perfect spatter free weld with the shop's current equipment, gasses, fillers, etc. if he wanted to... Because he has the process knowledge..... But that won't make a sale.

I would love to see a real time production example of MCAW outrunning or outgunning L59 solid wire in a normal structural setting with logical process controls with flat and horizontal fillets.

If you can't rotate your parts into flat or horizontal than FCAW is a friend.... But get ready to spend on fume extraction because OSHA is watching.

By js55 Date 06-06-2014 15:46

OSHA may be watching but in all of the fume tests I have run (and I've done dozens) not a single time has any fume even come close to the limits set by OSHA.
Talk about a scam.

By js55 Date 06-06-2014 15:54

Also, I will say that the advantage of FCAW over GMAW is reduced in the flat position, though it is still there, but taking your point about position work as a jumping off point, it is a rare fab shop indeed that has the luxury of no position work.

By Lawrence Date 06-06-2014 16:17

Also, I will say that the advantage of FCAW over GMAW is reduced in the flat position, though it is still there, but taking your point about position work as a jumping off point, it is a smart and profitable fab shop indeed that has the planning and process enginneering to eliminate position work.

Fixed  :)

By js55 Date 06-06-2014 16:51

Lawrence,
You seem concerned about the cost of fume extraction equipment but not about the cost of manipulators and positioners etc., and their higher associated maintenance costs, that would allow you to be 'smart' and 'minimize' position work.
Also, my primary field has been piping for these last 40 years. The best you can do in prefab piping is about 80% to 85% roll welds. What's driving it is trying to maximize that which is done in the shop from that which is done in the field. So assemblies become complicated. Even position work is preferred in the shop. You can't roll a refinery but you can do as much position work in the shop as possible to minimize the necessary position work in the field.

You can do a little better with high platforms and big holes in the floor but this comes at a cost as well. Not to mention a safety issue. Not so much falling off the platforms or into the holes, (though climbing up and down all day has its problems) but of having fixturing break loose on branches and large pipe that come crashing to the floor with a big'o thud. You can spend more time attaching it more securely but then, you are spending more time, and at some point it becomes counter productive.

However, I have spent time in structural shops as well and you will spend a lot of time flippin and floppin to get flats and horizontals without equipment as well. But then there's end plates.

Smart sure. But there is still a limit.
So to summarize,,,YOU CANNOT ELIMINATE POSITION WORK. And it starts to become prohibitively expensive and of diminishing returns when you get closer and closer to the idea.

And I haven't even addressed the idea of the cost of hiring additional 'experienced' people to manage all that job to job and piece by piece planning.

By Lawrence Date 06-06-2014 18:32

I'm mostly just having fun with the conversation here...  Thank you very much sir !

All the things you and I have mentioned and others as well need to be factored in... "Good Process Engineering"

I love FCAW and I love that the deposition rates have improved for out of position work in the last few years....

That yellow ESAB tag in the upper right hand corner?   They make .045 E71T-1  that will run vertical-up at 400 ipm with straight C02 with zero spatter... and 450 ipm with 75/25....   A great way to go out of position!

If you have no other choice :)

Lawrence,

I noticed that the article seemed to specifically target manufacturing.
I wonder how that will affect maintenance operations.
I spent 7 years in mining maintenance and Mn. is a primary alloy in "wear iron".
To implement $1000.00 respirators in to a field environment will drive up costs exponentially.

By js55 Date 06-06-2014 16:57

Lawrence, interesting you mention hex chrome.
The Cr is in the wire not the flux.

By Lawrence Date 06-06-2014 18:00

I only mentioned Chrome 6 as a comparison of renewed attention to engineering controls in the last decade..  The Chrome 6 levels and testing relate primarily to stainless operations and on site testing is becomming a common requiment and engineering controls of varying complexity are being implemented (often after hefty fines)

The Manganeese related to smoke/fume for SMAW/GMAW/FCAW/PAC/CAAC on plain carbon steel is what I really meant to highlight....  As chrome levels in plain carbon and HSLA steels are prolly still going to remain negligiable even with the 06 Hex Chrome reductions...

The 10X reduction of Manganeese may very well be a challenge for compliance when air sampling begins in earnest... Thats all I'm sayin.

By Lawrence Date 06-06-2014 18:12

Im a little less cyncial about OSHA than I used to be... A little.

I appreciate the requirments for MSDS...  I appreciate the extensive attention to tool guarding and electrical safety that OSHA has provided leadership with........ (Along with unions...ack)

They may be a bit overboard with this....  On the other hand... Lot's of old weld smoke breathers are sick old men...  If a few controls extend our lives... Maybe it's worth a look...

I don't have the info to judge this issue.

By js55 Date 06-06-2014 18:40

Lawrence,

Give em time.
They've only been around 3 or 4 decades.
Unlike the IRS who's been around off and on in one form or another for over 150 years, where the first tax rate was a measly 3% on, what was at that time, very high incomes.
Or take the monster EPA for example. Have you seen the size of the building they have in DC?
Or how about that humungous boondoggle Department of Education.
Governments do what governments do.
They get bigger and bigger until they suffocate the cash cow. Like a parasite on a host sucking its very life force until they kill it.

By aevald Date 06-06-2014 16:29

Hello Lawrence, very good points and certainly taken for their value. I have experienced a "definite" advantage with the MCAW wires on un-cleaned steel tubing(square, rectangular, etc.), the anti-rust coatings will play hell with GMAW(spray transfer), porosity and spatter mainly. In most instances, removal of tube identification paint(from the end of tubes) and a wipe-down/removal of the anti-rust coatings and identification paint is a requirement with a standard GMAW process. The MCAW, for some reason, in my experience, is able to weld through much of this with lesser issues. Many would say that removal of these items/elements should be a part of the fabrication process, yet we all know that the "should" part is often not the "done" portion of the process. My comments are not to say that I agree with use of MCAW for these reasons, if it in fact does perform without removal of objectionable coatings, but more to say that it might be cheap insurance for those instances where removal is not performed or omitted for any reason. Thank you for the information and best regards, Allan

By Lawrence Date 06-06-2014 18:19

I'm unwilling to pay fifty cents a pound for insurance :)

However, if the MCAW can cut cycle time by welding over a protective coating that code does not demand removal of... Or if a PQR proves that MCAW can weld over a coating...  And the cost is lower than the removal and use of solid wire...  Let's do it.

The scenerio you describe Allen sounds like a good one for MCAW.

By aevald Date 06-06-2014 20:17

Hello again Lawrence, I didn't realize there was such a disparity in the pricing of the MCAW. The last bunch that we got came from one of our compatriots to the north of us as a freebie. One of their local manufacturers had given them 3 or 4 tons of it so they shared the wealth with other welding programs that were at their facility for a conference. Good to know about the pricing issues.

One of the things that we chuckle about here at our school is when students don't pay attention to the identification tags on the consumables boxes and inadvertently grab a roll of it thinking that it's FCAW-G. They go to run verticals and come to us with some very puzzled looks on their faces and wondering where the slag is at. Best regards, Allan

Allan,

Please accept my apologies.
Admittedly I have lost track of this subject, surely due to having read your reply with some significant delay.

Considering and incorporating a row of different aspects (welding position, slag removal, fume generation, OSHA, CrVI, Mn, tax rates, ...) quite similar to welding this thread took an interesting and enjoyable 'non-linear distribution'.

In terms of your question I suppose, both nantong and js55 have already supplied valuable and most adequate responses.

Anything beyond that, at least in my opinion, would require a more quantitative assessment of the topic.
This, however, might lead to this 'exponential function' that I did recently mention.

Regards.

donnellythoccou87.blogspot.com

Source: https://app.aws.org/forum/topic_show.pl?tid=33542

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