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Up Topic Welding Industry / General Welding Discussion / Need some good starting perameters for Aluminum mig Pulse..
- - By Kix (****) Date 03-07-2007 17:35
Running on 1/2" plate T6-6061 base using 4643 filler.  Need volt and wire feed speed (ipm), wire size, gas, pulse settings.  Using a Miller Invision 456 power sourse with a 75 series feeder.   Weld size call out is 1/4" and 5/16".  I need to do some testing and prove a new process and knew you guys could save me a lot of time!!
Parent - By MNSTRBLDR (**) Date 03-09-2007 12:25
Kix, I wrote our procedure for 6061 T6 with 4043 wire and we use a Miller XMT 350 and XR wire feeder. I can't remember where the arc length was set to but my procedure says 390-420 wire speed and 16-20 V. Hope this helps, I can look into the pulse settings more if you need. Henry
Parent - - By Lawrence (*****) Date 03-09-2007 13:51 Edited 03-09-2007 13:54
If you are going to try to push that wire with your Miller feeder than you should have a dedicated gun for aluminum, that gun ought to be as short as you can make it and still get the job done, with a teflon liner and U-shaped rollers for your feeder. The internal guides for the feeder must be exactly sized for the wire as well to help avoid bird nesting.  No sharp bends or kinks in the gun while operating :)

The invision ought to have synergic Alum pulse parameters already downloaded. I doubt they have one preprogrammed for your 4643....you probably have a choice between 4043 and 5356, in which case you might start with the stiffer and higher alloyed 5356 settings for your trials.

Arc length will be adjusted by your "trim" knob for GMAW-P operations, the voltage will be set with the synergic CC/CV processer hosted within the power supply.

As stated above, around 400 ipm is a good enough place to start for wire feed speed.

If you are going to do alot of this type of work a push pull arrangement may be desirable.
Parent - - By js55 (*****) Date 03-09-2007 14:47
Lawrence,
Having never run pulse Mig on aluminum I need to ask. Isn't pulsing problematic for aluminum given its thermal conductivity? Especially for 1/2" plate.
Parent - - By js55 (*****) Date 03-09-2007 14:52
I guess another way of phrasing the question is, (in the spirit of Ed Craig) if you don't need the pulsing do you really wanna mess with it?
Parent - - By Lawrence (*****) Date 03-09-2007 16:35 Edited 03-09-2007 16:38
J55

"in the spirit of Ed Craig"   ...... always good to keep in mind.

The high rate of thermal conductivity is a thing the designers of parameters for the synergic pulse have worked out pretty well. Most of the GMAW-P I've done are on material thinner than half inch and the pulsation has made much Tig work obsolete due to the excellence of GMAW-P.

With material that thick pulse is certainly not required.

The nice thing about the *newer* GMAW-P units is that the pre programmed settings actually work.  (I have not test driven invision so cannot say one way or the other) With a Good pulser in working order, It's a two knob operation with the voltage taken care of by the machine.

But like "Max" says.... the GMAW-P does reduce overall heat input, which may be important.
Parent - - By Kix (****) Date 03-09-2007 18:00
I'm wanting to introduce preheat and pulse into this process on the 1/2" because right now with no preheat and spray mode only and 25.5 volts we're running i'm haveing major distortion issues as well as other consistency prob.  I want to preheat to say 250deg or 300deg and dial back the volts a bit, find a good wire feed speed and solve the distortion probs and weld consistency probs for these guys. I have been fiddleing with the .o62 4043 adaptive pulse setting and i'm liking it.
Parent - - By js55 (*****) Date 03-09-2007 18:24
Thanks Lawrence.
Kix,
The preheat certainly helps to address the COE issue I was wondering about. Excellent idea. Let us know how that turns out.
Additionally, does anybody know of any tech papers on the GMAW-P of Al. Especially heavier walls.
In reading ASM Vol 6(95), they provide a hardness traverse of 6061-T6 wherein the lowest hardness occurs at an astonishing 1/2" (almost) from the fusion zone (the overaged zone). This coincides with a temp range of 550F to 800F. Would the reduced heat input from pulsing shift this closer to the higher stress fusion zone? This is exactly indicated for GTAW in a further figure in Vol 6 where varying heat inputs not only moved the overaged zone closer to the fusion zzone, but as expected, narrowed it as well, with higher hardnesses. It would be expected that this is a good thing. So theoretically the threshold would be the point of insufficient fusion in the welding process.
This of course may just be theory talk. As Max says, to paraphrase, pull it, bend it, if its good, its good. And I agree.
But I'm curious.
Parent - By js55 (*****) Date 03-09-2007 18:28
Sorry, not thermal expansion; thermal conductivity
Parent - - By Lawrence (*****) Date 03-09-2007 19:27 Edited 03-09-2007 19:32
More of Ed's spirit!

I copied this from ol Ed's website this afternoon

"When welding all aluminum alloys, please note: To help retain the properties in the Aluminum HAZ locations,
always use low to conservative TIG or MIG weld parameters, think low weld heat. Low weld heat is one of the
great real world benefits of using the pulsed MIG weld transfer mode on aluminum applications.

"Aluminum provides welds that are less less viscous which is a problem when trying to get weld fusion with
the short circuit mode. Pulsed MIG is beneficial on all aluminum applications. The viscosity is beneficial when
using spray or pulsed transfer for all position welds."

"Pulsed MIG ideal for applications 0.040 to 0.100.
Over >0.100, traditional MIG spray transfer is beneficial."

"In contrast to MIG welding steels, the pulsed MIG process provides real welding benefits. The lower, attainable pulsedspray current avoids weld burn-through. Lower current means you can use larger wires.
Less weld smoke and less ozone generated"

http://www.weldreality.com/aluminumalloys.htm
Parent - - By js55 (*****) Date 03-09-2007 19:52
So I would surmise that in accordance with Ed, Pulse though not ideal for 1/2" is certainly not prohibited either, and given Kix's distortion problems, he is developing a possible alternative with preheat to solve the CTC problem and pulsing to solve the D and C problem.
UT's or hardness traverses on the HAZ (not to mention bends) would be interesting.
Parent - By Kix (****) Date 03-09-2007 21:32
Well, if your interested in all of the digits to the test i can give your the results when i have them.  I'm waiting on temp sticks at the moment and i won't have them till next week.  When i get them i'm going to qualify the procedure myself and get the coupons to the lab and i don't know how long results will take.
Parent - - By Kix (****) Date 03-09-2007 19:40
One other reason for the pulse at a lower end with preheat is i would still be getting good penetration and still controling the distortion issues.  So if pulsed gmaw was only suppose to be applicable for thinner guage material why would the make a .062 aluminum 4043 pulsed setting on our machine.  I know your not going to be welding .100" thick aluminum with .062 wire..
Parent - By js55 (*****) Date 03-09-2007 19:58
Kix,
LOL!!!  For guys who think outside the box with distortion problems.
Parent - - By Lawrence (*****) Date 03-09-2007 20:14
Since you may not have enough to think about already

Your fancy new Miller feeder also has "run in" controls that can reduce the wire feed speed at arc initiation for a fraction of a second (while keeping arc energy the same) which can get that aluminum heated up and help eliminate those cold starts that are common.

It also hase "crater fill" adjustments for the end of the weld.  This is also of value when craters cracks are appearing at weld terminations.

I've been doing some trials with these controls and my Lincoln Powerwaves lately and am beginning to see some real benefit.

I'm not a fan of whistles and bells for the most part and I HATE crater controls on Tig.... But for Aluminum GMAW I see a real benefit.
Parent - By Kix (****) Date 03-09-2007 21:38
Oh yes i totally agree about the starts and stops and plan on finding a good hot start setting for these guys so they can keep that grinder on the bench. While i'm doing that i may as well mess with the post flow and crater fill to omit grinding on that end as well.  I've got a lot of work ahead of me. lol
Parent - - By 357max (***) Date 03-09-2007 15:20
0.047/0.062 diameter wire, argon or 75/25 argon/helium, 30-40 CFH flow rate, set the Pulse Program to 4000 series aluminum of the wire diameter. If the 75 feeder has remote voltage control, this will become remote Arc Length TRIM control.
Fundamentals; wire feed speed makes the arc hotter/colder, deposition rate, penetration & travel speed. Set the wire feed speed and leave it alone. Fine tune the arc, by adjusting from the MIDPOINT of the TRIM value (50 with a range of 0-99), which adjusts the arc length. Longer/Shorter; if the wire pounds the plate, increase TRIM value, if the wire melts back to the contact tube, decrease the TRIM value. ALWAYS - ALWAYS -Set the wire feed speed first then fine tune the arc length with the TRIM value.
With a lower average heat input, pulse will provide better weld pool control, can change/improve mechanical strengths, a good test is worth a thousand opinions.
Parent - - By Eutectic (**) Date 03-11-2007 09:23 Edited 03-12-2007 04:06
Good morning to all,

Depending on how you measure HI it is now actually proven that p-gmaw give higher HI as average A and V are not applicable, instead the term "true power" is used to calculate HI but due to "older" calculation methods it is still believed that pulsed gives a lower HI.
As for pulsed on aluminium- use it on all the groove but welds and Pulse on Pulse for fillet and Cap passes
Furthermore on mechanical Properties the HAZ begins to recrystalize at 200degC and progresivly increases with full anealing taking place at above 300degC.
With what are you planning to preheat? oxyfuel gives offgas containing carbon and moisture - big no no.
then ofcourse all the other cleaning requiremnts of material and equipmant must be met for succesful welding

Good luck
Cheers
Parent - - By js55 (*****) Date 03-12-2007 14:07
I think that "depending on how you measure it" is the big variable. I have to think though that I am not convinced (as I would suspect as yet neither are the code bodies)that it is "proven" that pulsing has more HI. The standard functional or operational definition of HI is of course the common "older" formula. As such the HI would, it seems to me have to be related to the 'average' calculation (pk times, amplitude, etc.). The only way to avoid this is to change the operational definition of HI. Which is what I assume the research of which you refer has done.
My reasoning for doubt is that pulsing allows positional capabilties that spray does not based, I assume, upon total energy input into the amterial that is melted. Pulsing also still experiences fusion problems not as extensive in spray transfer. So, even given a "new" way of calculating HI to advantage pulsing, practical limitations seem to argue the opposite.
Having sid that, if you have nay papers available that oyu can either post or provide I wold love to take a look.
thanks
Parent - By Eutectic (**) Date 03-16-2007 05:14
js55 Email me at hfroneman@mcdermott.com
Up Topic Welding Industry / General Welding Discussion / Need some good starting perameters for Aluminum mig Pulse..

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