welding with aluminum

Date 11-12-2005 06:45

Hello Dennis, you have supplied some of the information that is necessary to make a judgement call on whether you can weld aluminum with your set-up or not, however there are quite a few other variables to consider as well. Thickness and size of the item that you are trying to repair or weld can be a large factor. The Hobart 140 wire machine that you say that you are planning on using is a very limited machine both in amperage/voltage output and also in duty cycle. Aluminum welding itself is a challenge with many much better suited machines let alone the one that you are considering using. If you are dead set on attempting to weld with your current set-up then you might want to consider a few things: use preheat prior to trying to make a weld, blackening the aluminum with only the acetylene on and then switching the torch to a neutral flame and running the torch over the area until the carbon has burned off will provide approximately the correct preheat, you might also consider brushing with a stainless steel brush after preheating to insure cleanliness and remove oxides, to go a good job of welding aluminum requires it to be as clean as possible and free of any and all types of foreign materials, if possible use a 5356 filler wire, this wire is stiffer than 4043 and will be less likely to give you feeding problems, if you end up with a cracking problem in welds you may have to go back to the 4043, the argon shielding gas will work, but a helium/argon shielding gas will yield more usable heat from your welder, you can experiment with a drag/push angle on the gun to come up with an acceptable bead profile, generally a drag will yield better penetration and a more convex bead shape and pushing will yield less penetration and a flatter bead shape and finally if your gun has a steel liner in it you may want to see about getting a nylon one to help with making the wire feed better, also, in any case make sure to keep the liner as straight as possible at all times. As a final note Dennis do not use an oversize contact tip in the gun, use the size that matches the wire diameter, oversizing the tip can cause arc stability issues and cause premature failure of the tip. Good luck, Allan

By djc Date 11-12-2005 23:21

Geezz. It's just square tubing.....seems like it would be easier to just use super glue. I'm going to give it a shot and see if it holds...... if my welds don't hold up, I'll call around to some of the shops around and see if someone can help. I don't want to get too deep into this small project.

Dennis

By djc Date 11-15-2005 03:00

I have given it a shot......I have the Amp on high (4) and the wire speed at 90. The Argon was at 18# and the wire kept getting fused in the tip. I lowered the Argon to around 12# and had much better luck. However, the wire still became fused in the tip but, not as often. I will try 10# of Argon and maybe a stiffer Aluminum wire if I can find some. What is the best way to clean the black from the aluminum?

By 357max

Date 11-15-2005 14:13

Couple of tricks to weld with these little machines. Start at the spool brake, set it's tension as low as possible, just enough to keep the wire from unspooling. Drive roll tension, set at absolute minimum, just enough to feed the wire. Maybe try a knurled drive roll. Keep the gun cable as straight as possible. Even consider hanging the machine above the work. Before starting the weld, each and every time, cut the wire to a sharp point. Using a glancing approach, start the arc, don't try to start an arc with the wire 90 degrees to the joint. 20 cfh gas flow. These machines will only produce a short arc/short circuit transfer, they will not produce the industrial spray transfer so keep the voltage low, that is a major cause for melting/welding the wire to the tip. Use a stainless wire wheel on a grinder and clean the oxide off before welding. Should work.

By Cat Mechanic (*)

Date 11-21-2005 02:30

Dennis,
A quick tip to make it easier to unstick your filler wire from the tip is to file halfway through the tip about 1/4" back from the end, leaving a trough that the wire feeds through. The wire will still stick to the end but you can pop it loose with your fingernail by bending it back toward the filed off section. I've done a fair amount of aluminum welding with a Lincoln SP 125 and the wire sticking to the tip seems to be a common issue with the small migs. They aren't the perfect machine for large aluminum fab projects but they are awful handy for small fab and mobile repair projects. I built a couple duck blinds and did some jon boat repair work with mine, the portability was a definate plus!
Hope this helps
Jim
357 Max is right, don't try to start your arc straight on. Pull the trigger to get the wire moving before making contact with your work, it will reduce the chances of wire burning back and sticking.

By bzzzzzzzzzz (**)

Date 11-21-2005 11:54

I tried it with my MM 172 with straight argon. It'll work, but it won't be pretty. The main problems were burnbacks into the tip and difficulty controlling the puddle. Likely they were both connected to the feed issues. I did mange to repair a casting which would've cost a few hundred bucks, so the experiment was still a success. I would do it again if a similar problem arose, but to weld aluminum on a regular basis there would be another machine in my owership.

By new tito (***)

Date 05-13-2006 22:59

Dennis, I have the same mig you do lincoln Sp125 plus I just bought some 4043 .30 wire and I have argon & helium mix, Can you tell me what your best outcome is as far as the heat and wire speed is for 1/8 thick alum? Also is Dc positive the right polarity......black wire on top, grey on the bottom?

Thanks!
Rob

By brande

Date 11-24-2005 05:52

You will have much better luck with a larger diameter wire.

.035 or .045 will allow a good deal more heat from the welding machine, possibly reducing your need for preheat.

On the subject of preheat, kepp it below 350F if you want the mechanical properties available from 6061.

Good Luck

brande