MIG vs TIG

I think MIG welding's advantage is in speed and ease as opposed to TIG. It's more oriented toward production welding where the welds will be hidden or otherwise out of sight (or where looks don't matter). A TIG welder in experienced hands makes much more attractive looking welds and is much more versatile. With TIG you can join dissimilar metals, braze weld, and weld extremely thin metal parts.

Why they TIG weld motorcycle frames on TV shows is anyone's guess. Probably the producers of the shows encourage the use of as much different equipment as possible to keep things "interesting." (I think they encourage the use of cut-off wheels on grinders rather than saws because of all the nifty sparks they emit, also.)

That being said, here's a photo of some TIG welds on the frame of a Ducati motorcycle:

I understand that Ducati does not try to hide the welds on their frames for aesthetic reasons. They think they look good. I agree.

Whoever wrote that sounds as if he's had some trouble with a MIG.. Heh. Haven't we all?

But.. I think it's safe to say that you can get by without a MIG easier than without a TIG/stick machine if you're doing a good variety of work.

John

Those don't look like any TIG welds I've ever seen. They look like MIG welds. I'm no expert, mind you. But, can anyone confirm whether or not these are TIG?

rvb

I think you have already given a balanced viewpoint. I have seen some MIG welded aluminum samples that were very impressive. They were done with a pulse arc current. Welding too fast can result in a quenching action. This could in some cases (steel) create a brittle heat affected zone. On the other hand TIG is slow and I have seen damage done to aluminum alloys by overheating the area. I didn't know what I was looking at but old hands who had done many aluminum fishing vessels spotted a problem right away. They figured after a season the vessel would be back for massive crack repairs. Wherever you go you will hear welders tell you that a certain procedure can't be done and you have to use such and such. Look around a bit and you will find someone making liars out of the first group. I come from a time when stick welding was the only safe way to join metals and all wire feed welding was "just junk". Just another example of the Flat Earth Society. Take your choice when it comes to what to use. Randy

I'm no expert, but particularly when you are talking one off work it seems to me that TIG is superior.

With MIG you have to correctly set the voltage and wire feed speed for the weld in question. While lord Ernie L. can probably hit the settings exactly right the first time, I don't think most mere mortals can. This means some testing and experimentation is necessary to get a quality weld. For production work this is fine since it's a one time thing.

By contrast TIG is a fully dynamic process where you can adjust the current and the filler feed on the fly to get the best possible weld, particularly in cases where you have differing thickness of materials.

If you watch most of those fab shows on TV you'll notice that they quite often use MIG to tack parts in place since it can be operated single handed and then when they finish that rough assembly they go through and fully TIG weld everything.

Pete C.

I don't know that this is meaningful for everyone, but while I own a MIG welder, I find TIG far more fun and rewarding. There is something great about actually manipulating and managing molten metal...

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I'm no expert either, but I had the same thought.

Peter

Remember the TIG can weld most metals that can stand the heat. e.g. won't vaporize...

So if you have some exotic steel and want a nice joint - that can't be seen - use some of that exotic steel as a filler. Some are copper - you can TIG that. and the list goes on...

MIG - you have to get the special feeder wire and it may not be available or ever made.

Martin

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Those beads look like they've been mig welded to me as well. The tig bead (when done well) is very uniform and looks like "nickels" overlerlaying on each other. I was at a motorcycle rally last year and saw a 2003 bourget diamond anniversary chopper that had the aluminum frame tig welded to perfection. The weld beads were so perfect it looked like a robot welded it. That was the best tig welded aluminum i've ever seen (and i'm always checking that stuff out... some sort of mental problem!) I feel that i get better penetration when i tig weld. I can see the metals puddle up better and once i get the puddle moving while adding filler the weld also looks neater. I know guys who can make oxy-acetylene, mig, stick, or tig welds look awesome, but they do it all day, everyday. The most important factor of any weld is the strength. Here's are some nice tig weld beads:

luck, walt

>

You may be right. The image is very small here (I had trouble finding good images of Ducati frame welds). I remember some show on motorcycles where they discussed a classic Ducati 750cc bike and they said that the welds (obviously TIG welds in those close-ups) were left as they were for the sake of aesthetics. That's what inspired me to try to dig up some photos online.

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No motorcycle chassis that is produced in any numbers, is assembled using manual TIG welding process. The cost of this alone, would make it impractical.

The only time a chassis would be produced using TIG process, would be low volume, special, or competition type frames, where cost is not such a major factor as would be high volume production items.

ken

Tig for versatility, Mig for production.

As far as roll cages in race cars, I don't know what the rules are today. But at one time the roll cages had to be chrome-molly steel (I don't remember the AISI number) and they had to be welded to aircraft specifications. Aircraft specifications call(ed) for gas welding only. As I said this was "Once upon a time..." and I don't know if it still applies to race cars, but I believe it may still apply to aircraft.

Hi Ken,

I don't believe that Ducati is a high volume manufacturer of the scale that the Japanese companies are. They make more of a high end niche market bike (In fact they are located within twenty miles of Ferrari's and Lamborghini's facilities and have a reputation similar to those auto makers). I can't find a specific reference to Ducati's frame welding methods, but here's mention of the MV Augusta F4 Brutale, a motorcycle in the same class as the Ducatis.

"In the S version, no longer a limited-edition, the MV Agusta F4 Brutale maintains the essential features of the Serie Oro exhibited a year ago at the Munich Show."

"The chrome moly tubular steel trellis frame connects to the rear swing arm fulcrum plate, while all welds are made using TIG technology."

Lamborghini's

Having been involved with motorcycles for more than 30 years I have not come across any production Ducati chassis, which was built using the TIG process.

Ducati is while not as large scale a producer as the Japanese, a factory that certainly manufactures thousands of machines, rather than low volumes in the hundreds.

Motorcycle chassis that are commonly assembled using the TIG process include those produced by the Verlicchi factory in Italy, made in aluminuim, and used on competition machinery.

ken

MIG is orientated to production environments where you need the speed. TIG is more versatle (gaps, filler, base materials, etc) but slower by a factor of 10 or so. Stick is your "get it done" process, especially in construction.

In a production environment I've seen MIG used to do .049" wall exhaust manifolds welded in lots or several thousand at a time, 6" schedule 40 aluminum pipe weldments, and stainless fittings spray welded to stainless pressure vessels at the rate of hundreds per shift. I wouldn't suggest a hobbist or even a pro to do this with a MIG for a single piece.

I have > I'm sort of new to this group and welding in general. I've been trying to

Cool can I buy one of those unused MIGs cheap?

A few shots (not the best camera) of TIG welding of thin titanium tubing on a Merlin ExtraLight road bicycle. They are a beautiful thing to see: (photos are about 60KB in each)

Wow.

Those are pretty incredible.