Aluminum Mig Help

By Lawrence (*****)

Date 07-15-2009 16:37 Edited 07-15-2009 16:49

Of course surface prep must be perfect with aluminum, even with GMAW.. Any surface oxides will promote lack of fusion..

Assuming good surface prep.

Spray transfer settings for your wire diameter could be between 400-470 ipm and between 22-28 Volts.

You want to use a push gun angle.

You should see spray from the end of your electrode wire but you need to keep the arc gap short (distance between the wire end and the base metal) 1/8" max..

If the electrode wire is stubbing into the work, increase voltage in 1/2 volt incraments until smooth spray.

If a long arc gap is observed, reduce voltage by 1/2 volt incraments until a nice shore arc gap is achieved. Long arcs tend to make the plasma cone bell shaped and undercut and fusion issues follow.

If you are using the GMAWP options than you would adjust the trim upward to increase the arc gap length and decrease the trim to reduce the arc gap length.

Many aluminum welders want to produce a whipped "row of dimes" appearence.. Only the most experienced welders can produce test quality welds with this technique.. Whipping spray transfer GMAW with aluminum can cause fusion issues both at the root and sidewall.

For performance testing (PQR or welder performance) use straight stringers to get best results... And since this is the method that produces best results, why not use it in production unless specs demand a ripple appearence.

Sometimes the XR feeders must also be calibrated to the power supply (accomplished between serial numbers and touchpad)... your owners manual or miller rep will be able to help with that.

Edit:

Here are some factory parameters
http://www.hobartbrothers.com/pdf/datasheets/Smootharc5356.pdf

Also.. I'm in the upper Midwest too.. Wisconsin/Ill. stateline area.

By aevald

Date 07-15-2009 16:40

Hello 52757, I don't have a lot of time at the moment, but if you go to www.millerwelds.com and look up the particular machine that you have there is a spot at the bottom of the page that links you to Miller's tech tips. If you follow this path to "aluminum mig" it has a lot of really good starting information that might help you folks out. There are also a number of really good resource people here on the forum that can and will help also. Before I forget, welcome to the forum! If I get a bit more time I'll see if I can contribute a bit more. Best regards, Allan

By bozaktwo1 (***)

Date 07-15-2009 16:48

Hey, and welcome to the forums.

You laid a lot of information down, so let's see if we can't figure out your problem. You didn't mention any cleaning process, and that's where I always start when aluminum is concerned. First, I recommend you invest in some good, stiff stainless steel wire brushes. Use them to scrub the oxide layer off the base metal at least 1" on all sides of the joint. Second, clean the base metal with acetone, alcohol or even MEK to remove any residual oils (even a fingerprint can ruin your day). You'll want to clean vigorously between passes. The sooner you begin welding after the wire brush, the better. Additionally, you might consider some sort of wash for your base metal prior to joint prep. DaraClean works pretty well. My usual base metal is 6061, and I use nothing but 4043 in all our wire feeders, with push-pull machines. In my experience 4043 runs cleaner and with greater penetration that 5356. Another thing to look at is possible gas contamination.

Are you using a WPS? If so, who qualified it? I have learned tons from qualifying my own procedures, and it provides foolproof data that doesn't lie.

From the data you give, I would hang my hat on cleaning procedures, and perhaps technique. Hope this helped a little. For much more info, try doing a search in the forums under aluminum and see what you get! Good luck.

By 52757

Date 07-15-2009 16:55

Thank you, That is what we are trying to do is to qualify the process. Great info coming in,I appreciate it guys.

By bozaktwo1 (***)

Date 07-16-2009 16:33

One thing I should caution you on is that if you try to go with 4043, make sure its strength is going to be adequate. There is a large difference between UTS of 5356 vs. 4043.

By makeithot (***)

Date 07-18-2009 18:47 Edited 07-18-2009 18:58

Seems every one has coverd the essentials of sound aluminum welding but just to add my two cents. Wire brushing is of course necessary but I have found that at times is not all that is needed as the brush will pick up some contamination over time and just smear it from one place to the other. So to take the process one step future when doing hull plate welds etc I will use a file for the finale step. This does produce excellent results . As Alan has also mentioned the miller site has a lot of great info as well that may help you pin point the specific problem. It has also been my experience that it is not offten the fault of your equiment that is causing the proplem I run the same gear that you are using and find it to be very user friendly. Regards Richard.
PS. Are you trying to do this weld in one pass, I would not as the heat required will produce porosity and also lack of fusion try two passes if this is the case and results will be better, Use a skill saw to clean between passes with no lube and a sharp blade this will also improve and produce great results

By SundownIII Date 07-26-2009 05:00

52757,

Have not used that particular Miller machine, but my LWS just delivered one to a local marine fabricator.

Looking at Miller's GMAW Handbook, it would appear that your arc voltage and amps are way too high for 3/64 wire. Their tables are for 4043 vs 5356, but I've found them to require similar volts, with the 5356 needing a few more amps (faster WFS). Their tables show an Arc Voltage of between 22-31V, Amps between 130-290A, and a WFS of between 250-650 IPM.

My experience says that cleaning of the aluminum is important with GMAW (Spray) but nowhere near as important a factor as it is with GTAW.

Might try dropping those settings back a tad and give it another go. I weld 3/8" 6061 all the time with a MM251 and 30A spoolgun and it won't get close to those V/Amp settings.