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Welding Aluminum with Miller Syncrowave 200 [Copy URL]

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Post time 2013-5-1 02:51:45 |Show all posts

Hi guys,

First post here. A little back ground and then the question.

My first welding was with act/oxy and coat hangers when I was 22 years old. I still use it for brazing and sweating at times. Eventually I got a Lincoln 225 cracker box for stick and about 16 years ago now a MillerMatic 185 MIG. MIG is about all you need for most automotive work but for some time I have wanted the TIG process and bought a Miller Syncrowave 200.

My first project was stainless and since then a few mild steel things. Since I am a former Chevy mechanic my sons and I build a few hot rods here and there and I have looked forward to being able to fabricate aluminum and stainless parts. My first aluminum project was a toe-in gauge for doing front end alignments. I will just say it works fine for the purpose but the welds are not anything to write home about. I had no trouble with the 1/8” thick material but the main beam is a very thin 1/16” square tube. Welding the thick to the thin was difficult for me but I got it done.

Here is my main question:

I know I need more seat time for starters but I seem to have trouble focusing the arc in A/C at 60hz. It’s not a problem for me on thicker material but an example of what I want to do is welding in a threaded bung in the tank of an aluminum radiator. My machine has high frequency start but that drops out once the arc is established. Do I need high frequency to weld thin gauge aluminum and still have a reasonably sized bead? I am not opposed to selling this machine and getting an inverter machine if I need to. I just don’t know what role the high frequency plays in the results of welding thin aluminum and when it becomes a requirement.

Thanks in advance,

Steve

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Post time 2013-5-1 02:51:47 |Show all posts

Thin AL has been welded with the Sync 200 for many moons.






Chapter 6 should get you headed in the right direction

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Post time 2013-5-1 02:51:49 |Show all posts

When doing AC tig, HF should be continuous regardless of thickness. I'm not even sure I can change that with my Sync 200 in AC. I know on the Sync 250's you have to manually change the HF, at least on the older ones.

If you need a tighter arc...

Be sure the tungsten isn't contaminated. Thats usually the 1st issue I spot with people learning tig, especially those that are trying to jump ahead fast and before they've learned the basics. As soon as you dip, stop and regrind.

Tungsten shape and size. If you are running green with a ball, your arc will be larger than with say lantanated and a point with the same size tungsten. Also with thin material, you'll need to possibly drop down in tungsten size.

Practice... Practice ... practice... If you don't have the basics down cold on steel, alum is usually a PITA. This becomes progressively more difficult the thinner the alum gets. Everything becomes progressivly more critical. Prep, tungsten size, arc length, heat control and so on. You can get away with a long arc length on say 1/8" and make it work, but you can't on 1/16" and less as easily. Can you do these welds in say stainless or mild steel, perfect every time? If you can't, you'll never have any luck with alum that size regardless of the machine.


My guess is that you need a lot more seat time, probably starting with thin steel/stainless. It's a common fault with new tig guys. They don't want to put the time in learning the basics. They want to jump right to what ever they want to do and think they can make it work.

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Post time 2013-5-1 02:51:51 |Show all posts

The manual mentions high frequency start but there is no adjustment for frequency. Can someone explain to me the advantages of high frequency? Does HF change arc shape? What do you see or what can you do with HF that makes it better or at least different than the standard 60hz frequency? Maybe I just have this stuck in my head but I would like to know from someone that has welded with both.

Can I weld mild steel and stainless perfect? No. I have no illusions that my tig welds should look like my mig welds at this point. I joined this site to learn. I only just now have enough seat time to even begin to ask these questions. For a while there I spent more time grinding tungsten’s than I did welding.

Let’s talk about mild steel. I seem to have trouble welding too hot. I have a 3” exhaust system project coming up and I am thinking of tig welding all the joints. I have practiced a little on some left over 2-1/2” 16ga tubing and while I never blew a hole in it some parts of the weld slumped inside the pipe a little. That is not good for exhaust flow in a high performance application. I suppose it just takes seat time but my HAZ was much larger than what I would have had with my MIG welder. Any tips on reducing HAZ?

Steve

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Post time 2013-5-1 02:51:53 |Show all posts

An idea what your settings are, what tungsten and size would help. The more info we get the better the suggestions can be.

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Post time 2013-5-1 02:51:55 |Show all posts

72nova,

You need a better understanding of what HF is/does.

I'd suggest that you go to Millerwelds.com and click on the resources tab. There you'll find an offer for their "Student Pack" ($25 including shipping). This includes an excellent Tig Handbook, a GMAW Handbook, as well as a bunch of other goodies.

On your Syncrowave 200, when in AC mode (aluminum) the HF should be continuous. HF does nothing to change the arc shape (as changing the freq with an inverter does). It simply maintains the arc as the squarewave transitions from DC- to DC+. Without the HF on continuous, the arc would "studder" as it passed thru the 0 state.

I've welded "thin aluminum" with Syncrowaves for over 30 years and not experienced the problems you're encountering. Not trying to be a jerk, but lack of seat time/experience is not a valid reason for blaming the machine for what you're having trouble doing.

As DSW has already mentioned, using a 2% Lanthanated tungsten, sharpened to a crayon point will help with what you're doing. The lanthanated tungsten will still form a ball, but it will be much smaller than that found with the pure. Arc length is critical with thin aluminum.

There are things that you can do with an inverter (variable frequency, etc) that can optimize your "bead appearance" but, based on your comments, you're not at a point where that should be a factor.

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Post time 2013-5-1 02:51:57 |Show all posts

HF is used to jump the gap between the tungsten and piece being welded, that way you don't contaminate the tungsten. Adjustable frequency on an inverter allows you to narrow the with of the bead especially in welding a t-joint. Seat time is no joke you should commit yourself to spending 100 hrs of seat time before tackling any projects. Start with 1/8" thick steel and weld in diff joint configuration when you think your doing alright then go thinner and so on . Then you start the process over with SS and then Al. An inverter has more bells and whistles and most people can't leave them alone and makes learning more difficult.

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Post time 2013-5-1 02:51:59 |Show all posts

Thanks for the advice fellas. The main purpose for my post was to verify that my machine does not preclude me from welding thin aluminum or that it should only be attempted with this machine by the most experienced tig welders. I am not trying to blame the machine, only verify. I think we have established that this machine is perfectly capable of that quest. The guy at Praxair where I bought it said it was the highest rated machine in its class and I wasn’t trying to save any money but I didn’t want to spend $5,000.00 if I didn’t have too either. Under what circumstances would you justify the purchase of an expensive inverter machine? Production shop? Aerospace work? What?

Broccoli1 and SundownIII, I downloaded the handbook and read it from cover to cover before I ever turned on the machine. I have referred back to it frequently but like you guys have said it is no substitute for seat time. SundownIII, on AC, my machine has a rhythm or as you described a stutter that is unlike DCEN when welding mild steel. I assume this is normal as it flips from pos to neg . Does the air gap in the machine have anything to do with this? I have never checked it as it is new.

Jay O, I have much less than 100 hours. I built a box with butt welded outside corners from 18Ga stainless sheet to house a carbon pile for load testing batteries. Most of it was just fused without filler. I have only recently started welding thicker mild steel stuff and even those welds are flawed but I have to say the welding process was more enjoyable. On a fillet weld I have problems with undercut so I agree; I need to practice on thicker material and then move back to thin. It’s just frustrating because I have been butt welding automotive 20 ga sheet metal for years with my mig and before that I actually stick welded it at times. I see top automotive fabricators tig welding all the time and I just want to join the club. I will do whatever I need to do to get there.

DSW, I don’t know if I have found any solutions here but at least I have some ideas of what to pay attention too. I have tried both 3/32” and 1/16” pure and 2% thoriated with both sizes of filler rod. I have not tried lanthinated. I have headed the warnings about cleanliness and that is not an issue. I have to say I have played around with AC balance and don’t notice much difference. It seems the arc starts out pretty good and progressively wanders. I noticed the tungsten gets sort of frosty looking so maybe I have it set with too much DCEP. Based on the handbook, my arc length is way too long if it should be the diameter of the tungsten. With that length I have trouble dipping the rod without colliding with the tungsten. I don’t dip so much as I touch the rod to it. Torch angle is probably not ideal either. I typically set the machine to around 150 amps on 1/8” flat and use the foot pedal to control the heat. With aluminum it takes a lot of pedal at first and towards the end I almost can’t get out of it enough. Maybe I should bring in the pulse control which I have not tried as of yet.

I know I am new to tig but I am not a new welder. I would be considered at best a hobbyist and I know the time spent away from the machine is damaging to my progress. When I need to weld something I want to be able to just pick it up and weld it. It is my goal to be at least adequate at this and I am not too proud to accept advice and/or instruction. I think to reach that goal I need to commit to regular practice and sign up at the community college for a tig class under the watchful eye of an instructor. They say practice makes permanent and that goes for bad habits as well as good. You guys have been very helpful and I appreciate your time and council. I will try to keep you posted on my progress and even throw in a few pictures.

Thanks again,

Steve

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Post time 2013-5-1 02:52:01 |Show all posts

Steve,

One of the best indicators of proper balance setting on AC is the "etch zone" adjacent to the weld bead. A large etch zone indicates that you're probably running too high on DC+. I've found that on new/clean aluminum, that on the Syncrowaves, a balance setting between 7-8 works well.

You may wish to try the 2% Lanthanated tungsten. Takes heat a lot better than the pure. It will still form a ball, but not as large as the pure. Also, I've found it doesn't form the series of small ba11s around the tip as the Thorieated does. Most LWS do not stock it. I get mine from tungsten-direct via the internet. I use it on both the transformer and inverter tigs.

I wouldn't worry too much about the pulser on aluminum at this time. I seldom use it on aluminum. Now thin SS is a different story. I have used the pulser, with new guys I'm working with, to help develop their dip timing.

Comparing mig to tig is a difficult proposition. Kinda like comparing shooting a rifle to shooting a pistol. I can leave the rifle in the safe for months at a time, pick it up and still shoot "dang well". On the other hand, if I don't shoot a pistol pretty regularly, I can quickly see a drop in accuracy. Tig welding requires not only the knowledge to perform the task, but also the development of the multiple motor skills (muscle training) to do it well.

As far as your "point gap settings", if you're getting consistent arc starts in both AC and DC, then your gap setting is probably fine. I've never had to adjust the points on a new Syncrowave. Sounds like, what you're experiencing in AC is the normal transition of the wave from DC- to DC+. The HF will be on continuously as it is needed as the squarewave passes thru the 0 (no current flow) state. This is happening at 60 cycles/sec.

Taking a "tig course" could be beneficial, however, my experience is that there are very few really "good tiggers" teaching welding. It is amazing though how just a few hours, one on one, with a good tigger can help to shorten the learning curve. Dallas/FW is a large area. Possibly there's a good tigger in the area that would be willing to work with you for a bit. If you were closer, I'd be more than willing to spend a little time with you getting the basics down.

As far as "where the inverters shine" that's a whole story in itself. By increasing the frequency, you're able to better focus the arc. This can result in deeper penetration and a narrower bead. I really like and use the high speed pulsing on the Dynasty for welding SS. All these things are "nice", but remember we've been tig welding materials for years without all these "bells and whistles". Give me an experienced tigger with a 330 A/BP (sine wave machine) and he'll run circles around a new guy with a Dynasty 350.

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Post time 2013-5-1 02:52:03 |Show all posts

Thanks for the pistol/rifle analogy Sundown. That helps a lot. As long as I know my machine is capable, then it’s just a matter of practice. I will see if my LWS carries lanthinated or order some on the net and give that a try.

One more thing. I have had trouble at times with the filler rod sagging before I get it to the puddle with 1/16" aluminum rod. I think the tungsten was a bit contaminated, my arc length too long and maybe the torch angle too flat. Am I on the right track?

Steve

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