What is TIG and MIG?

[HMF]

[h=2]What is TIG and MIG?[/h]TIG - Tungsten Inert Gas; also called GTAW -- Gas Tungsten Arc Weld, but nobody calls it that except the American Welding Society (AWS)
A small torch with a tungsten electrode is used to make the arc inside an envelope of an inert gas, usually argon or some argon mixture. A filler rod is manually introduced to complete the weld. The resulting weld is very pretty and usually requires no further finish. It is used mostly for welding sheets of mild steel, stainless steel or aluminum. The better machines have a foot control and a high frequency arc starter. Any sizable stick welder can be retro-fitted to do TIG welding, but without the foot control.

MIG - Metal Inert Gas
MIG and wire feed are the same thing. In this process, a consumable wire electrode is fed from a spool to the torch where the weld occurs inside an envelop of pure carbon dioxide, pure argon or a mixture of both. The weld continues as long as the operator has the trigger depressed and there is something to weld. This process is very fast, easy to learn and results in fairly good looking (better with argon) and strong welds. Most production welding of mild steel is now done with MIG welding. There is no slag to chip, but there is a slight thin coating of a glassy material that probably should be wire brushed off before painting. MIG welding can be used for thin or thick materials and is commonly used on mild steel, stainless and aluminum. Some common features of MIG machines are spot welding and stitch welding of sheet metal.
There is a special wire called flux core that can be used in a MIG welder without the shielding gas. This process leaves a slag coating that must be chipped off. For most people on this group there isn't much use for flux core, as it was developed to reduce cost for large- scale welding where the cost of Argon starts piling up.
There are fairly cheap 120 volt MIG welders that will only weld thin sheet metal. A more practical 240 volt machine that will weld up to about .25 inch is about $1500-$2000 new, $800-$1200 used. The machine I have will do MIG welding and stick welding, but most are MIG only. A machine that will weld .25 inch in a single pass will still weld thicker materials with multiple passes.

 

[GA Gyro]

Good thread idea!

TIG and MIG are mis-understood; their best applications are mixed with ease of use and purchase price.

TIG is, IMO, the preferred way to do strong welds on light materials, especially aluminum. If one has ever done Oxy/Acetylene aluminum welding, they know...
MIG is quick and easy, the big box store welders are not pricy and can do simple welding jobs and repairs.

There is also 'stick' welding, for heavier metals... however stick is giving way to MIG.

One of these days, I need to look into a MIG attachment for my Lincoln gas powered stick welder/generator.

I have a customer who has one of those Miller Dynasty 200's... the one that has the HF problem. Wondering if I got it for a good price, if I could fix it. Did a little googling, all I found was folks griping about the machine.
Anyone know the whats and whys of this issue, and a potential repair?
THX in advance for any information!

THX again for the thread!

 

[Ed.]

There is also MAG which is the almost the same but uses an active gas mix (Metal Active Gas), this is what most general welders use, but it is still referred to by most welders as MIG welding, so to sum up, anything that uses a coil of wire as the filler metal will be generally called MIG welding. It may not be technically correct but nearly all welders will know what you mean.

Cheers

Ed.

 

[chuckorlando]

Flux core is wire feed yet not mig. IMO

 

[zmotorsports]

Subscribed.

Great topic Nelson. You mentioned the correct AWS (American Welding Society) nomenclature for TIG, GTAW (Gas Tungsten Arc Welding) but didn't mention the correct term for MIG, GMAW (Gas Metal Arc Welding) so I thought I would throw it out there.

Also a slight correction, straight argon is not used nor recommended for MIG/GMAW. This is due to the fact that it is truly an inert gas whereas CO2 actually carries the arc and helps to stabalize it. There will be little to no penetration with straight Argon. Straight CO2 is relatively inexpensive and therefore quite common with many high volume shops, however, those who really go for quality and at a little higher cost will run a C25 mixture which is 75/25 Argon/Carbon Dioxide. The Argon protects the molten puddle whereas the slight amount of CO2 stabalizes and carries the arc for the penetration aspect of the process.

Then you can get exotic with tri-mixes for spray transfer arc welding. These are generally 90% Helium/7.5%Argon/2.5% CO2 but can vary slightly on the Argon and CO2. Some welding supply stores will play with the percentages a very little bit to cater to certain weldors in their area.

Most of us for general MIG/SMAW welding use the short circuit type of welding. Spray transfer arc welding/mig welding is done on large weldments where high voltaage and very high wire feed rates are used. I see these types of welds a lot on forklift masts and other large structures in the industrial industry.

 

[iron man]

I use a tri mix that is argon/c02 with 2% 02 you can spray transfere with it on steel or stainless with no spatter.. Ray

 

[CluelessNewB]

There are also new 220V (or multi-voltage) MIGs like the Hobart 210MVP or the Miller 211 that fill the gap between the low end MIGs and the higher end machines. They run in the $900 - $1200 range new (retail not list price). They don't have the duty cycles of the better machines but fit the bill for some of us hobby folks. There was just a review here of the Miller 211 a few days ago, the Hobart 210 MVP (what I have) is very similar. http://www.hobby-machinist.com/threads/very-friendly-millermatic-211-mig-welder.32525/#post-275708

 

[Rbeckett]

To put it in simple terms TIG is Thermal Inert Gas welding that covers the weld zone with a non-reactive gas and you feed filler into the heated joint with your off hand. While maintain the required tip to work distance and angle. The tungsten electrode does not become any part of the weld unless you accidently dip it in the weld puddle. MIG is a cinstant feed consumable wire that is shielded by an inert gas such as CO2 or a mix that allows the arc to burn a little hotter. Tig is the most difficult to learn to do properly and requires many many ,any hours of practice to get that perfect looking stack of dimes weld bead. That look is not required for a satisfactory weld but that's what any welder worth his salt does on a daily basis. Mig is fast sweet and can produce very high strength welds if the proper parameters are selected prior to welding. I do both and have been doing Tig for about 10 years every day for 12 hours a day 7 days a week while I was deployed in Iraq. Tig is also the weld of choice for sanitary stainless steel welds and repairs due to the look and complete fusion of the base materials with a compatable filler so theat it doesn't lose it rust resistance. LMK if you would like a better or more thorough explanation.

Bob

 

[Tinkershed]

I know this is an old thread but thought some of the low experience welders (like me) might be interested in something I discovered. I wanted to learn something about basic fix the lawnmower deck sort of welding and after perusing some you tube videos, bought a Harbor Freight Easy Flux 125. Before anyone asks I have no interest in HF except as a source of inexpensive tools . The Easy Flux 125 is a DC inverter welder which is a huge step up for a basic Flux Core welder. No it doesn't do gas but as a first welder it is pretty good. The reviews have been outstanding and it will handle 1/4 inch plate if you groove the weld path. It isn't advertised for that but many have used it on 1/4. Best part is it runs on a 20 amp 120 V circuit. I have done several repairs with it and have gone from knowing nothing about welding to the very bottom rung of the ladder. Cost is about $180 with a Coupon plus a mask and gloves. I know gas is better and I know the fancier machines are better but for the cost, this one is really decent.

 

[addertooth]

One of the advantages of the "moderately maligned" Flux wire welding rigs, is the ability to work outside where a breeze pushes the shielding gas from a classical MIG welder out of the envelope space. Properly performed, and with the right flux core wire, the slag left on the surface of the weld brushes away rather easily. Other key things to remember with flux core welding is "correct polarity" and using "spatter spray" to reduce the amount of spattered metal deposited outside the weld area. Flux Core welding often results in the "least pretty" weld, but is quite strong.