|12-05-2004 03:49 AM|
The tungsten itself becomes oxidized after putting down a certain amount of weld beads. You'll notice the tungsten becoming light grey or off white. This means it's time to change the tungsten. The strength of the arc will deminish from the oxidation on the tungsten tip. Allowing the tungsten to stick out too far or removing the tungsten from the completed weld before post purge cooling of the weld will decrease the effectiveness of the tungsten which will have to be reground and balled up using DC-Positive as mentioned on my previous post.
The oxidation on the aluminum requires alot more heat than the aluminum itself because aluminum oxide on the surface melts at 3,700 F while the base material melts at around 1,200 F so that is why it is critical to remove the oxidation before welding. Also degreasers work best to prepare the weld, but make sure the degreaser doesn't contain hydrocarbons. Cleaning aluminum can be done simply with soap and water. I've done this many times with great success. Etching soultion is also an option for cleaning the material. Before beginning to weld use a stainless steel brush and brush ONLY in one direction. DO NOT brush heavly on the area to be welded or you could add contaminates to the weld.
And again I'd like to remind that a GAS LENS is critical for the cleanist welds possible regardless of the material being welded. The standard is a collet body but the gas lens body consists of a series of coarse and fine screens inside the collet body which gives better shielding of argon on the weld and provides optimum laminar gas flow to allow your welds to look their best. The gas lens also allows the tungsten to be extended out further for improved weld joint access.
|12-04-2004 09:21 PM|
I found the hardest part of aluminum welding was to keep everything CLEAN,CLEAN,CLEAN.
I clean the weld area with MEK or acetone to remove any oils and finger prints,then use a stainless steel brush or stainless steel wool to remove oxidation JUST BEFORE welding and then use the stainless steel wool to clean the filler rod to remove any oxidation from the rod. Aluminum can oxidize in MINUTES so clean just before welding. Most sanding disks and grinder wheels have resins that bond the abrasive together and will contaminate the weld area so avoid grinding the area clean. Carbon steel wire brushes and steel wool will contaminate the weld also.I always break off the contaminated tungsten but one of my teachers told me grinding the tungsten was OK! GO figure?
I use a 30 year old miller 250E-HF with no special controls like the new electronic ones have and once get it set to the amperage I want and everything CLEANED, welding Aluminum isn't really any harder than steel .
And remember the old welder's trick to pretty welds: go over any ugly welds with the torch and run a" line of fusion" to smoothen out the weld area to make it more appealing looking
|11-19-2004 10:16 AM|
zonk heres my two cents you didn't say whether your useing a gas shielded tig welder 1. tungsten [green] 1/4" sticking out balled 2. angel 10/5 degrees off vertical 3. gas argon set at 25 4. clean all pts 5. move tig 1/4' per rod dip of travel. keeping tip 1/4" off work this will help doug
|11-18-2004 11:24 PM|
|4 Jaw Chuck||Always make your ball by stiking your arc on a piece of copper, a penny works in a pinch. Only use silicon carbide wheels to grind the tip shape, aluminum oxide wheels contaminate the tip.|
|11-16-2004 06:45 PM|
It's been awhile since I welded aluminum but if I remember correctly I would stick the whole tungsten out about 1/2" and switch the polarity to DC-positive and hold the torch vertical over a half inch thick piece of copper or bronze. And slowly ramp up the amps creating the ball on the end of the tungsten. You then have to slowly ramp down to prevent a crater or hole from forming on the tungsten ball, otherwise your arc will sometimes go directions you didn't want it to. Don't forget to switch back to AC.
I dont recommend grinding tungsten that has been dipped into the weld puddle. Instead hold the tungsten off the edge of a steel table at a slight angle and use a bronze hammer or whatever you got and break the contaminated tip off. An instructor from Miller taught me these things. If you do want to grind the tungsten use a grinding wheel that is only intended for aluminum. Use a separte wheel for other metals.
Use the largest gas lens you can find. It has wire mesh inside that allows the gas to flow better over the weld and also use Argon + Hydrogen for cleaner welds.
Also the key to good uniform welds is being relaxed. Resting your arm on a some thing that is propped up to keep your hand steady. This goes for your other hand that has the welding rod too.
Make sure your aluminum is preheated enough before starting the weld puddle. If you don't you get booger welds. Watch the joining aluminum pieces become wet looking and then apply some rod to form a puddle. Add the rod every second or two depending on your speed. And also remember to breathe. I use to hold my breath when I first began welding.
Adjust the tungsten so it is sticking about 1/8"- 3/16". When I was welding aluminum housings I would pull the tungsten out further and notice alittle more penetration of the welds.
|11-13-2004 08:36 AM|
Zonk, here's a couple more cents worth from a non-expert. I use the shortest electrode extention that I can get a stable arc with. The shorter the better since it helps to keep contamination away.
Also depending on how tight the joint access is, I will play around with different nozzel diameters. I like to use a small diameter tungsten and nozzel on thin materials.
I don't do much aluminum so when I do I spend more time practicing on scrap before I get to the objective...lol.
|11-12-2004 12:12 PM|
|zonk||Out about a 1/8 inch did have some trouble with arc , might have found a small answer|
|11-12-2004 12:06 PM|
|Beenaway2long||Depends on the angle of the torch tip. I stick mine out 1/4". The tighter the tip to the cone, the harder to see what your welding. Harder to strike the arc, too. Could you even stike an arc, if it were inside the cone? You'd really have to "pedal it" to get a high enough arc.|
|11-12-2004 12:04 PM|
|zonk||I can't remember this, does the tungsten sticking out of nozzle or not have any effect?|
|11-12-2004 11:48 AM|
Balling the end is correct, just make sure when grinding tungsten ANYTIME, not to use a contaminated wheel.
Welding up mild steel- sticking the tungsten- you stop and grind it so contamination doesn't effect the weld. Now,you weld for a while, an decide to ball the end for aluminum. If there was contam in the ground tungsten, it will still be present when you ball it. See what I mean. You need a separate wheel. My TIG instructor was a fanatic about it. You should see the way he "stacks coins." Try the smaller rod with the ball.
Another thing for nice welds- Be in a comfortable position,too. Vertical position welding doesn't look as good as horizontal.
|11-12-2004 11:38 AM|
|zonk||Jeff, have taken some short classes on tig, understand aluminum can be a pain,be carefull of contamination, was told on the tungsten to ( ball the end) strike an arc with tip and let produce a small ball the diameter of tungsten, when tig steel to have a pointed end on tungsten. Perhaps I should've tried smaller tungsten. Do appreciate the help. I don't tig to often,however I do think its kind of fun to try.|
|11-12-2004 11:26 AM|
When you grind your tungsten, be sure to use the wheel ONLY for tungsten. Otherwise you'll get a porous weld, and it will have all sorts of black in it. You may want to use a smaller tungsten, too. Radiator tanks are awefully thin.
|11-12-2004 11:07 AM|
Tig Welding Aluminum
If someone is good at tig welding aluminum need some tips:
Tig welding some mounting brackets to my aluminum radiator, welder set on ac, remotes on, high frequency switch down, amps 90, ac balance set at 3, 1/8 in pure tungsten (green tip) with balled end, cleaned everything real good and used a clean stainless brush. My question how to get those nice tight uniform welds ( be sides practice.) Welding 1 in aluminum angle to side panels fortunately most is hidden, nothing bad just wide welds not to pretty but they'll hold. Does having the tungsten in or out of nozzle have any effect? Any tips I would appreciate at least to go back and practice.