Hello Bill, everyone has given you some valuable information here. Unfortunately there are lots of variables to be considered when you are trying to make GMAW aluminum welds. Since you are using the spoolmatic setup you will first have to insure that you are hooked up on the correct polarity, it should be reverse polarity, the gun should be hooked up to the + output of the machine and the ground should be -. Next be sure that you have the correct size contact tip to match the wire diameter that you are using, also be sure that the drive rolls that are in the spoolmatic match the diameter as well. Then check the contact tip position relative to the gas shielding nozzle, it should be flush to around 1/8" recess. As was mentioned the flow rate should be set somewhere between 20 to 30 CFH, you can play with this a little since the lower flow rates will help to conserve on your gas usage. A straight argon gas will work very well and sometimes an argon/helium gas will work better, as you are just starting out you will probably want to use the Argon. When you are getting ready to start the weld you should advance the wire somewhere between 1/2" to 5/8" of stickout past the nozzle end with a freshly cut end, the spoolmatic has a manual gas valve incorporated into the trigger so when you go to start partially pull the trigger until you notice the gas starting to flow then completely depress the trigger to start the actual welding, Once you have completed the weld you will need to let off on the trigger to the point where it stops welding but doesn't cut off the gas, allow it to flow gas for just a brief moment and then release fully, by using this method you will clear the welding area of atmospheric contaminants before the arc has started and then upon completion of the weld you will protect the molten puddle from contamination while it cools below it's oxidation point. A properly done GMAW aluminum weld will have a shiny finish on the bead and a small amount of whitish oxidation on each side of the bead beyond the actual edges of the bead, there should not be any black residue in or around the bead, if you see this it is an indication of either surface contamination or lack of shielding gas or something of this nature, occasionally you will see this blackish condition at the start of the weld. Machine set-up has lots of variables to take into consideration, wire diameter, material thickness, preheat or not on the part to be welded, size of the part to be welded, all of these will be variables that need to be addressed when selecting the proper voltage and wire speed to be used. There are some basics that you can go by when you are trying to figure this all out. If you start with say some 1/4" material, try a voltage setting of around 22 to 24 Volts and an initial wire speed of 3 to 4, start the weld, if the wire seems to push real hard and looks as if it is pushing into the puddle, raise the voltage some, do this to the point that the wire no longer pushes into the puddle and instead burns off above the puddle. On the other hand if the wire appears to be burning back towards the contact tip, either increase the wire speed or reduce the voltage until you have the wire burning off slightly above the puddle. Once you have the wire burning off above the puddle as I have described, look at the bead that is being laid down, if it appears to be narrow and seems to stand up off of the surface of the material you will need to increase the voltage and set the wire speed faster accordingly, if the bead seems to be wide and flat you will need to reduce the voltage and set the wire speed accordingly. Some folks like to oscillate the aluminum wire, others like to simply drag or push it, if you push the puddle it will tend to be wider and flatter with less penetration, if you drag the puddle it will usually be narrower and built up more and have greater penetration, oscillation, from my point of view, helps to wash the weld metal to the edges and help to avoid undercut on the edges of the bead, you can practice these methods and see which best suits your purpose. Remember the aluminum needs to be absolutely clean when you are welding it, use a stainless steel brush on oxidized aluminum and use acetone on aluminum that has oils, cutting fluids or other surface contaminants before trying to weld. Sorry for the windy reply, look into additional information regarding welding aluminum if you have time, it will be invaluable to doing a good job when it comes to welding it. Best of luck and Regards, aevald
Bill,
Take Aevald's advice!
Paying attention to these details will help you succeed.
Good luck!
Brad
Awesome! Thanks for the detailed information. As a rookie I can use all the advice anyone is willing to offer, and your advice is certainly appreciated. All I need now is some practice!
Aevald,
I also agree with your procedure. If Bill follows the parameters you suggest, his beads will look great. And, of course...practice...practice...practice. I like the push method best, but at times, had to pull. I keep my Ar near the 30cfh for a real clean weld. It takes a bit to get the hang of Alum. because of its rapid heat & cooling cycles, but after a while, you can "feel" the puddle. Also, I have found that pre-heating any Alum. casting will give superb results. AND...with Alum., cleanliness is next to godliness ...Denny
That was an excellant response, lots of necessary information. I have not used GMAW with aluminum for a long time, but reading those details brought back good memories. I did not notice if a spool gun or a torch mig was being used, but the only thing I could add would be if a torch mig is use.....use care to keep the lead as straight as possible to prevent wire kinking and burn back at the contact tip.
Yup, just like Lawrence stated....you need the gas, even for practicing. Are you seeing any porosity(porosity= holes, lots and lots of holes) while practicing without the gas turned on? ;)
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