GTAW pulse frequency and amplitude

By Lawrence (*****)

Date 08-05-2011 09:55

There is 150 amps difference between high and low pulse????????????

With that kind of current why are you running GTAW at all I would like to know?

I'm sure you have good reasons Joel... But I can't think of any.

What's the alloy group?

By js55

Date 08-05-2011 12:26

Joel,
I might suggest you purchase more synergic machines. :lol:

Seriously though, I do not have ready to hand any info on a rule of thumb relation for peak to background, to me their determinatives are independent. Peak amplitude is related to wire spead and ensuring a one droplet per pulse syncrony along with frequency.
I sure ain't no pulse expert and perhaps Lawrence or Marty (Stephen was good at this stuff too, whom we haven't seen in awhile)can help here, but this should all be programmed with the latest technologies.
However, it may be tied in to arc stabilization and too extreme a variation in any given frequency.

By defaced (**)

Date 08-05-2011 13:37

I develop mechanized GTAW procedures for a living. Here's my 2 cents. Thinking back to my WE classes, C. E. Jackson had a set of equations for determining penetration based on arc current. I know they were for SAW, but we'll assume the same trends follow here. So, in short they meant that increased current means increased penetration. That's how you set primary current, get a current that gives you the penetration you need. Background current is used to cool the puddle down (notice you lose penetration when you go into background). Because you don't want the puddle to have to completely re-establish itself, limiting the difference to less than 100 amps typically works out ok at typical GTAW currents. Now if you're up at say 700A for primary, yea, I think dropping down 150A in background would be very acceptable. Having said all that, there are no "rules" just good guidelines that work most of the time. If you're not welding a "most of the time" application, then the "most of the time" guidelines don't apply.

By TimGary (****)

Date 08-05-2011 13:55

Ok, so I'm no pulse expert, and have never pulsed GTAW, but here's my $.02...

The benefit of pulse technology is that a pulse peak gives you good bead wetting and penetration characteristics while the background allows the puddle to cool enough that it freezes slightly, resulting in better puddle control during out of position welding and for welding thinner materials.
Once you consider that the pulses occur between 60 to 120 times per second, it would make sense that the higher amplitude of the peak, the less the puddle will freeze during the background.
At a certain point of over balance, perhaps the puddle can no longer freeze at all, negating the benefit of the pulse?

Tim

By defaced (**)

Date 08-05-2011 14:07

Pulsed GTAW is usually done at 1/2 to 2 Hz.

By Metarinka (****)

Date 08-05-2011 18:28

some more information. this is pulsing to increase arc efficiency. Not for wetting on say an oscillated weld or to prevent undercut at the toes. Pulse rate has been varied, going from 50hz to 5Khz (yes 5khz) at those frequencies the arc tends to constrict and give more penetration for a given current. Thanks henry for the links I'll take a read through several of them.

The delta is 150 amps but the peak is under 300amps

By Blaster (***)

Date 08-05-2011 21:58

Wow, what power source do you have that pulses at 5K hertz? The highest I have seen has been about 500 if I recall correctly (Dynasty 700 and old Aerowaves).

Nothing scientific here, but when using a fast pulse to stiffen the arc (normally 200 hz or higher) I like to use 20 - 35% as a background amperage setting. But then I only use a fast pulse when working at low current levels.

By Metarinka (****)

Date 08-06-2011 07:30

using several different ones, they are all miller inverters designed for automated use.

By OBEWAN

Date 08-05-2011 14:25

The rule of thumb for orbital GTAW processes is to use a 3:1 peak to background ratio. I have used that rule to convert automated orbital programs to manual GTAW procedures with great success,

By ssbn727 (*****)

Date 08-05-2011 16:46 Edited 08-06-2011 05:12

Joel,

Chew on these links & .pdf's for a while, and I'm sure you'll find something that will help your own specific application even though you give us practically nothing to work with for obviously good reasons...

These folks are known to solve problems... Pick their brains a little and see if I'm right:

http://www.pcc-york.com/index.php/militarygovernment

These folks are good at what they do and I'm sure you already recognize some of them from you previous position.

http://www.pro-fusiononline.com/pdf/pwt-aug99.pdf

http://www.pro-fusiononline.com/feedback/pwt-aug99.htm

Here's a couple of articles which may be of interest to you:

http://www.arcmachines.com/industries-served/nuclear/plutonium-bearing-containers

http://sti.srs.gov/fulltext/ms2002053/ms2002053.pdf

http://www.thefabricator.com/article/esab-welding--cutting-products/robotic-gtaw-or-gmaw-no-longer-a-clear-cut-choice

More stuff:

http://www.ysxbcn.com/upfile/soft/20110402/06-p0467.pdf

http://pii.sagepub.com/content/225/2/270.full.pdf+html

Materials Sciences and Applications, 2011, 2, 251-257
doi:10.4236/msa.2011.24032 Published Online April 2011 (http://www.scirp.org/journal/msa)
Copyright © 2011 SciRes. MSA

Process Parameters Optimization of an Aluminium Alloy with Pulsed Gas Tungsten Arc Welding (GTAW) Using Gas Mixtures

Pawan Kumar1, Kishor Purushottamrao Kolhe2, Sashikant Janardan Morey3, Chanchal Kumar Datta1
1Department of Mechanical Engineering, Delhi College of Engineering, Delhi, India; 2 Department of Mechanical Engineering, Agricul-tural University, Ratnagiri, India; 3Department of Production Engineering, College of Engineering and Technology, Akola, India.
Email: {kishor_kolhe, ckd5929}@rediffmail.com, pks_munesh@yahoo.com
Received December 7th, 2010; revised February 1st, 2011; accepted March 4th, 2011.

ABSTRACT
This paper demonstrates the enhancement of mechanical properties and effective optimization of pulsed GTAW process parameters on aluminium alloy 6061 using sinusoidal AC wave with argon plus helium gas mixtures. Modified Taguchi Method (MTM) was employed to formulate experimental layout and to study effect of process parameter optimization on mechanical properties of the weld joints. Microstructural characterization of weld joint was carried out to under-stand the structural property correlation with process parameters. Keywords: Pulsed GTAW, Aluminium Alloy 6061, Gas Mixtures, Mechanical Properties, Modified Taguchi Method, Microstructures... Here's the link to the .pdf:

http://www.scirp.org/journal/PaperDownload.aspx?DOI=10.4236/msa.2011.24032

These folks really know their stuff when it comes to Variable Polarity GTA pulse welding parameters... Why not pick their brains a bit??? :roll:

http://www.liburdi.com/LiburdiAutomation/Pages/LTP400-VP.pdf

http://www.liburdi.com/LiburdiAutomation/Pages/LT1000-HS.pdf

http://www.liburdi.com/LiburdiDimetrics/Gold-Track-VI/White%20Papers/GTVIapplicationsBrochure.pdf

http://www.liburdi.com/LiburdiDimetrics/Gold-Track-VP/White%20Papers/GTVP_datasheet.pdf

Here's a very cool tool if I may so myself :twisted:

:

http://www.liburdi.com/LiburdiDimetrics/MSIV/White%20Papers/MSIV_Liburdi_Votech.pdf

Here's another one:

http://www.liburdi.com/LiburdiAutomation/Dabber/White%20Papers/Dabber_000.pdf

More articles:

http://neuron.tuke.sk/~vascak/predmety/FSR/Eseje/Muller%20-%20Fuzzy%20control%20of%20pulsed%20GTA%20welds%20by%20using%20real-time%20root%20bead%20image%20feedback.pdf

Check out these papers and see if they are of any interest to you:

http://traidia.free.fr/

Check out this paper also:

http://www.comsol.com/papers/7901/

Here's another good paper:

http://www.osti.gov/bridge/servlets/purl/919545-5GcnMB/919545.pdf

More food for thought:

http://sta.uwi.edu/eng/wije/vol3201-02_jan2010/documents/RootPassWelding.pdf

This is something that may not be directly useful to you yet it can be interesting nonetheless:

http://www.engr.uky.edu/~ymzhang/Papers/Wu%20Post%20Paper%204.pdf

http://www.engr.uky.edu/~ymzhang/Papers/Wu%20Post%20Paper%203.pdf

http://www.lhu.edu.tw/m/oaa/synthetic/publish/publish/20/1.%E8%94%A1%E7%93%8A%E6%98%9F-Model%20and%20control%20Pulse%20GTAW%20for%20steel%20pipes%20by%20Real%20time%20RBF%20neural%20networks.pdf

And of course, we must not exclude our old eclectic friend - Ed Craig and his site which has some interesting nuggets of welding wisdom:

http://www.weldreality.com/tigData.htm

This one (I highly recommend), you need to go to the right of the screen and find the .pdf link which will then open up s small window towards the top... Then you need to click download and the .pdf will open in a separate web page .pdf:

http://www.jmst.org/EN/abstract/abstract7134.shtml#

Another fun article although, not as good as the previous one:

http://mtf.tu-sofia.bg/mtm/lit/books-welding/RoboticWelding-II.pdf

Here's an older article/paper or two:

http://ieeecss.org/CSM/library/1994/aug1994/02-AutomatedWelding.pdf

http://lib.semi.ac.cn:8080/tsh/dzzy/wsqk/selected%20papers/welding%20journal/70-11-287s.pdf

This one I'm sure Professor Giovanni Crisi will be proud of:

http://www.jatm.com.br/papers/vol2_n2/JATMv2n2_p203-210_Advances_of_orbital_gas_tungsten_arc_welding_for_Brazilian_space_applications-experimental_setup.pdf

Another fun paper:

http://zurnalas.mechanika.ktu.lt/files/393-KahM173.pdf

More good stuff:

http://www.aws.org/wj/supplement/Ko02-01.pdf

http://www.waset.org/journals/ijame/v5/v5-4-37.pdf

This will put you to sleep:

http://prr.hec.gov.pk/chapters/254S-2.pdf

This one is visually stimulating:

http://www.sut.ac.th/engineering/Metal/pdf/MetJoint/04_Weld%20microstructure01.pdf

A fundamentally good article or two from Miller Electric:

http://www.millerwelds.com/resources/articles/Advanced-TIG-controls-greater-performance/

http://www.millerwelds.com/resources/articles/TIG-GTAW-frequency-amplitude-balance-waveform-controls-inverter/

http://www.millerwelds.com/resources/articles/Dynasty-200-Pulsed-TIG-GTAW-welding-exhaust/

http://www.millerwelds.com/resources/articles/search/search-results.php?welding_application=&welding_category=5&welding_kbi=&tags=&submit=Search

These are the last ones I'm posting since after all, This post has to end somehow:

http://smartweld.sourceforge.net/Tech_Disc2.htm

http://www.ysxbcn.com/upfile/soft/2008928/2008928143017681.pdf

http://sti.srs.gov/fulltext/ms2003085/ms2003085.html

http://www.ijest.info/docs/IJEST10-02-05-04.pdf

Respectfully,
Henry

By Metarinka (****)

Date 08-06-2011 07:27

as always henry, a treasure trove of weld research that you seem to find. I've skimmed through a chunk of the articles and I've found some very good gems of information

By kcd616

Date 08-07-2011 04:20

Henry,
Where do get all this stuff?
I have 35+ years in welding and you 1000+ years worth of knowledge.
You are one of the best.
Thank you for your time and consideration.
Sincerely,
Kent

By ssbn727 (*****)

Date 08-07-2011 17:56 Edited 08-07-2011 17:58

Ohhh a little bit of this and a little bit of that.... :eek:

No seriously, I somehow (I haven't figured this all out yet) have a natural ability to do a search on a specific topic regardless of what it may be, and come up with some pretty interesting results once I personally "filter" through the results of multiple search (I won't tell you how I do it because it's something I'm working on to possibly market in the near future) queries simultaneously until I compile a decent group of links which have at the very least, some direct relevance to the particular topic or subject matter...

This is my primary objective when compiling my results although I must admit, there were times in the past where the focus on my primary objective wasn't always razor sharp as it is nowadays... I can only guess that like welding & fabricating, experience is the best teacher which means (not to toot my horn too much now) that I'm probably getting a little bit better at this as the years go by. :lol:

:

I guess it was because I was too busy back when I was still working and since being retired once again, I have less and less distractions even with the time I currently spend training senior citizens on optimizing the use of personal computers to their advantage.

Anywho, enough about me... Thank you for those kind words but, there are members in here who are much more knowledgeable than myself when it comes to welding science and practical knowledge... :eek:

And finally, I'm always learning new "stuff" online while I search & filter links which is probably why I enjoy doing what I do in here so much besides probably being a tracking hound dog in my past life. :lol:

This would explain why I've been told that I'm "so tenacious & persistent" when searching for relevant links online. :twisted:

Respectfully,
Henry

By 99205

Date 08-08-2011 00:05

Someone has already done it. It's call the Dog Pile Browser.

By ssbn727 (*****)

Date 08-08-2011 00:17 Edited 08-08-2011 03:43

,
Ohhh, Well then, does it individually verify in a human way the relevance of each link to the query give, or does it do the same old primarily "boolean" search method that just about every browser uses including Google & anyone else? I didn't think so...

If they're using AI (Artificial Intelligence) then they must have improved things since the last time that was attempted which resulted in severe disappointments for the public who initially tried it :roll:

.

When you come up with one that can fully understand not only the gist of the query being asked in here to the letter, and not just the title of the thread, please let me and the rest of us know about it so we can test how good it really is. :eek:

Besides, I donn't rely soely on search engines to validate the links I post... I rely on my own knowldge, experience and understanding what the person who's making the query really looking for... Any search engine or browser cannot do that to the degree I'm able to accomplish so far. :eek:

However, please let me know if do you indeed find something better because it would certainly make my own searching a whole lot easier. :lol:

Respectfully,
Henry

By DaveBoyer (*****)

Date 08-08-2011 01:31

There is definately a nack to it, My sister is good at finding things with search engines, and knowing what key words to use, and what to exclude.