Jump to content
HybridZ
johnc

MIG vs. TIG

Recommended Posts

From "Mr. TIG" (http://www.tigdepot.com):

 

So....you purchased a MIG machine. You took it home and immediately plugged it in to "test" your skills on long awaited home projects. You have fairly good results and your chest swells with pride. Your machine is typically set-up with "gasless" filler material commonly known as "Flux Core". It welds ok, but you find that if you want "clean" results you need a bottle of Argon/Co2 75/25% mix and "bare" filler wire. You then read in the instruction manual that you can weld aluminum, but you need to change the wire feed rolls and replace the Steel Gun Liner with a near frictionless "Poly" or plastic Liner........Oh, and don't forget that now you need to get a new bottle of 100% Argon for aluminum.

 

Now that you have made the changes in your system, purchased or leased the additional gas bottle, changed the filler to aluminum, you are ready to go. Once you pull the trigger you are quickly surprised and almost disillusioned with the results. It would be kind to say you produced a weld. In fact, the results are HORRIBLE!! Fear not! You are one of millions that believed you would get excellent results from your machine. The fact is, MIG (metallic inert gas welding) is very easy to learn when applied to Steel applications. The less expensive machines, (under $500.00) typically do not have precise controls and are difficult to "tune-in" to thin materials, (under 16 ga.). They also are not good for material in excess of 1/8", therefore, your window of opportunity is 1/8" to 1/4" steel.

 

Enter TIG Welding.................the TIG welding process, commonly known as "Heliarc" allows you to weld most weldable materials including 4130 Cr-Mo, Stainless, Aluminum, Titanium, Magnesium and many other materials. Not only can you weld a variety of materials, but with the variable "foot control" you can adjust amperage on the fly and weld super-thin materials, typically as thin as 24 ga. Using only Argon gas, it allows you to weld all of the materials mentioned, so what's the catch? Simply put.............TIG requires more skill. Very much like gas welding, you have to manually apply or "dab" filler material into the puddle using cut length alloys of diameters of your choice. The TIG torch provides the heat source through tungsten and you hold the tungsten directly above the area you are welding. Depress the "foot control" (very much like a car accelerator) until you see a "liquid" puddle. Dab the filler into the base of the puddle, (not the middle), and move at a slow consistent speed, dabbing the puddle as you go. This method of welding is slower than MIG, however, cold lapping is virtually non-existent with TIG, whereas it is somewhat common in MIG.

 

Why isn't everyone using TIG? For many years the TIG machines were extremely expensive and were focused towards industry. Now, the hobbyist, hot rodder, motorcycle builder or kit plane builder are the focus of attention. Machines are now smaller, lower cost, designed for the garage, (power requirements are 115V and 220V and typically require no more than a 50 amp circuit). So the best way to get started with TIG is to................get started!!

 

MIG TIG

 

Cost..........................................$150-600.......$550-$1800

Material thickness (steel)..............up to 1/4".......same

Productivity................................fast...............slow

Quality.......................................average.........excellent

Variety of materials.......................limited...........most

Skills Required..............................2-4 hours......20-40 hours

Thin materials (24 to 16 ga)...........difficult..........easy

Thick materials............................easy..............easy

 

Note: comparisons are based on the home hobbyist and machines not rated at more than 185 amps. Material thickness based on steel applications. Hours for Skill building reflect a level of "feeling comfortable" with the process.

 

Good luck, Mister TIG

Share this post


Link to post
Share on other sites

Good stuff, but all review for me.

 

I would like to contribute some info:

 

For body work, use a MIG. It causes less heat thus less metal warpage (spot welds).

 

For structural pieces or not finish work use TIG. It has more penetration in the base metal and welds at a higher temp thus letting the metal cool slower which makes it stronger than what you would produce with MIG.

 

Metal Prep is paramount and can ultimately effect how a weld will turn out.

 

I suggest getting a second argon tank for purging if you plan on welding tubing with TIG, so use use it to run argon through the tube and weld the outside, not an issue if you're welding chromemoly.

 

 

Oh I just noticed: MIG vs "TIC" ?

Share this post


Link to post
Share on other sites

Spelling problems... :redface:

 

I suggest getting a second argon tank for purging if you plan on welding tubing with TIG, so use use it to run argon through the tube and weld the outside, not an issue if you're welding chromemoly.

 

You can use your existing tank just add a split after the regualtor and use bronze wool to seal the tubing ends. BTW... purging behind stainless and aluminum is important and its also important for 4130. Much less important for mild steel.

Share this post


Link to post
Share on other sites

I guess you can do that, but its just more of a hassel another hose on when most of the work doesn't require it. Plus I like it when I forget about the second tank and find out I need to get more argon, just swap the tanks out and get the empty one refilled later.:)

Share this post


Link to post
Share on other sites

I'm pretty sure that GTAW would probably be better for bodywork and finish welding, just because of the control you have over the heat. I know that at weld school we have to keep the NiCu under 350 degrees while welding. MIG is probably used more often because its fast and easy.

 

What I like about the GTAW machines we use is that you can do SMAW by just changing out the cup for a stinger and flipping a few switches. SMAW is nice because its fast, while still having control over the weld.

Share this post


Link to post
Share on other sites

Myself, I have ever TIG welded before..

 

Mig welding I do Ok, but it was with flux cored wire... so it wasn't very pretty..

 

Oxyacetylene welding, on the other hand I do very good at. Very clean, even welds with it...very nice beads.

 

Now having said that, wouldn't the TIG welding fall in between gas and mig welding... as far as the process goes.??

Share this post


Link to post
Share on other sites

I can't think of the words i want to use but they will come to me later and i'll edit this

 

Mig high metal output (you put down a lot of wire) lower heat induced

tig less metal more eat induced more likely to warp.

 

I still like Tig over mig whenever i can. i like the cleaner look. but you still got to mig sometimes

Share this post


Link to post
Share on other sites
Myself' date=' I have ever TIG welded before..

 

Mig welding I do Ok, but it was with flux cored wire... so it wasn't very pretty..

 

Oxyacetylene welding, on the other hand I do very good at. Very clean, even welds with it...very nice beads.

 

Now having said that, wouldn't the TIG welding fall in between gas and mig welding... as far as the process goes.??[/quote']

 

If you can gas weld, then you will probably do pretty well TIG welding. You need both hands with TIG. One to work the torch (arc) and the other to feed the filler rod into the weld pool. The TIG torch can be used to work the weld pool around. Guys who have only MIG welded have a harder time adapting to the separate heat and feed motions.

 

I bought a gas set up in high school because our old house couldn't support an electric machine. I got very good at gas welding. The couple of times I TIG welded it worked well also. I still suck at MIG welding, although I seem to be getting better at it. I really miss being able to pull the fill rod out and angling the torch to get the penetration I want. With a TIG/gas set up, the slower you go the more penetration you get. It took something JohnC said to make me realize that doesn't work with MIG. Go too slow and you just end up welding on top of your new bead.

Share this post


Link to post
Share on other sites

Thanks John for a great post. The thing I walked away with was how economical TIG machines have become. Price range is still high for a hobbist but within reason. I to will be in the market for a welder shortly. Having done collision, restoration and bodywork for twenty five years, I am no stranger to a MIG machine. I'm quite certain I could teach a smart dexterous chimpanzee how to MIG weld in less then five minutes... ANYBODY can do it. point, push button, weld. TIG on the other hand, is more difficult to master. Cruez, you say you can oxy acetylene weld? Well you would be a good candidate for someone who could pick up TIG welding pretty well. It is similiar in that as the article states, you feed in filler rod with one hand while positioning the heat source (the electrode) with the other. When you gas weld you hold the rod in one hand and the torch in the other. Unlike a mig, you control how much filler is added using judgement learned through practice. You learn to hold the tip of the torch just so to heat the area you need to weld.

When I did a lot of panel replacement, a MIG was the tool of choice for bodywork. Doing factory recommended unibody repair meant doing spot welds, lot of them. Usually quarter inch holes are punched or drill in one panel and the hole then filled to join the two panels. A MIG was fast, reducing warpage. You dial in the heat and wire speed on the first few welds, then go to town. Like Mike said the lower end stuff is not very adjustable so you are limited. For years at work we used a Millermatic. It was a great machine. I did a couple year stint in a machine shop that did mostly racing stuff. The owner had a nice TIG and what he could weld with it was amazing, all the way from paper thin steel all the way up to cast magnesium casings.

Share this post


Link to post
Share on other sites

You can TIG weld stainless and carbon steel with any DC welding machine using straight polarity. Carbon does not need to be purged on the back side. I have seen a TIG pulse arc machine weld an aluminum Budweiser beer can back together, talk about low heat input.

Aluminum is where you need the square wave Tig machine.

I worked as a certified pipe welder for years, never used a MIG welder in the field. I have a MIG welder with gas shield in my garage now and it will work on most any project that I have. I would like to have a DC machine for Stick and Tig welding, but really do not have any project coming up that it is needed.

Share this post


Link to post
Share on other sites

Who makes a $550 TIG machine? As an engineer I spent some time in the heavy manufacturing industry and was actually a part time (pretend) weld engineer. I've sourced many units and have always wanted to get one for myself but couldn't afford it. Most of the used units I delt with were over $1000. I've been away from the industry for awhile but I've never seen an entry level TIG for less than $1000.

Share this post


Link to post
Share on other sites
If you can gas weld' date=' then you will probably do pretty well TIG welding. You need both hands with TIG. One to work the torch (arc) and the other to feed the filler rod into the weld pool. The TIG torch can be used to work the weld pool around. Guys who have only MIG welded have a harder time adapting to the separate heat and feed motions.

[/quote']

 

Thats what I was thinking about the TIG welding.. I think I would pick it up pretty easily.

 

Come spring, (when my bonus arrives :) ) I think I am seriously going to look at a TIG unit.. personally, I think it would suit me better than a MIG unit would.

Share this post


Link to post
Share on other sites

harbor freight has a DC GTAW welder for $350 before tank and regulator... I am saving for a Miller Dynasty 200DX. I am in welding school and have been GTAW welding for about a year and have been able to make some beautiful welds on mild steel, stainless, and aluminium...GTAW is definitely my favorite process of them all. And if you can weld with oxyfuel then GTAW will be easy. I have also welded Mig and am takeing my last course in overhead SMAW welding and Prep for Industrial Qualification starting in January.

Share this post


Link to post
Share on other sites
I have seen a TIG pulse arc machine weld an aluminum Budweiser beer can back together' date=' talk about low heat input.

Aluminum is where you need the square wave Tig machine.

[/quote']

 

For body work, its also about application of heat also. The area of the base metal that the heat/arc is applied is much greater with TIG than with MIG spot welding. You can do Body work with TIG but MIG does a much cleaner job (after dressiing the welds) and is more cost effective.

Share this post


Link to post
Share on other sites
Is 25amps low enough for a MIG to do bodywork? Is'nt there some sort of spray on stuff you can use to improve the finish of non-gas MIG welds?

It is, but you have to remember that Flux burns hotter. When welding thin metals with MIG you REALLY need gas. I have a little Lincoln 100 weld-pak thingy I use and really enjoy, but I'm running flux. Ive been doing alot of body work on my Z, replacing rusted sections and such and lemme tell ya.. It aint no picnic. I can lay good beads on 16g but any thinner and I run into problems. On the Z metal (22g?) its impossible with flux. Someone running a high-end machine could probably pull it off, but if you have a high-end machine you should have gas anyway. I can barely even tack the Z metal, heh.

 

Its such a wretched pain I've put all work on hold until after Christmas when I have the money to go ahead and upgrade to gas and run some solid wire.

 

Thats not to say Flux doesnt have its place. As the flux burns it often breaks up and carrys contaminates away from the weld puddle.. Which is helpful when welding dirty or rusty metals that cant for whatever reason, be prepped properly. It also helps with penetration on thicker metals due to the increased heat. Useful when your welding in the upper limits of your machine and need some extra "umph".

 

As to dressing the welds, a flap-disc will do wonders for the appearance of Flux welds, lol. A slag hammer to knock the crap off, hit em with a flap disc and they dont look half bad. I'll see about getting some pics of my "dressed" coupons.

 

Something else I'd like to add -

 

If your in the market for a welder, *DONT CHEAP OUT*. Stick with the big boys. Esab, Lincoln, Hobart/Miller and Thermal Arc. HF welders are **** and I wouldnt trust one as far as I could throw it. I've had the displeasure of welding with one. I coldnt tell you the unit as its been a while.. But man. The arc was hard and angry, the machine just isnt quality. My Lincoln - for its size and price - has a softer, more managable arc and I really enjoy using it. The general consensus when buying a machine is "Bigger is better" and it really is true. Get the largest machine you can possible fit into your budget. Shopping around is your friend as well. You can save ALOT of money.

 

I screwed myself by buying my Lincoln too early. I paid something like 380$ for it or somesuch at Lowes. It didnt come gas ready, but can be upgraded (beware, some small units CANT be upgraded to gas). The next-in-line welder that was gas ready was (I beleive.. its been a little bit) about 450$. Lincoln 125 I beleive. Since I have to upgrade to gas now, I have to buy the kit for my welder, which is 100$, putting my cost at 480+ tax on the kit. So closing in on 500$. If I had just waited a little longer I could have got a machine that was 25amps stronger than mine, came with a slightly better gun and came gas ready from the get-go. Not to mention the little "kit" it came with had a better hood than mine, lol.

 

Another thing to consider when buying a MIG unit (well, any welder that uses gas) is the gas itself. Getting a bottle can be expensive and tricky. Some gas suppliers wont honor leases through other suppliers - so beware. Some suppliers also wont fill *any* bottle they didnt sell, rent or lease you personally. This is annoying and costly - as they tend to charge a little more than online prices. My advice would be to talk to local welding shops and gas suppliers before buying your welder, just so you know where to go and what to expect. See what they will and wont do for you and what kind of prices to expect. Would suck to buy a bottle through supplier A when supplier B wont honor the bottle but charges less for gas. Calling local welding shops is helpful as well they can point you to a good supplier. Expect to lay out somewhere to the tune of 150$ to get a bottle and get it filled. You sometimes work out lease agreements for more money upfront, but that will save you time, money and hassle down the road. Its all up to you intended use and pocket book.

 

Bottle size is also important. For the average hobby welder, you dont need an 80cf tank, 40 or 60 will work fine - the gas lasts a good while.

 

As to the folks talking about TIG units.. Some machines will come in under 1000$. 500$ even but these machines usually do NOT include the gas equipment/torch/foot pedal. So it adds up quick. The 500$ machine ends up closing in on 1000$ by the time you buy everything you need to make it work.

 

I dont know what your budget looks like but this sucker is about the best bang for your buck in the mid-range TIG market. Someday I'll be buying that sucker. Someday. Anyone need a kidney? Lung? Non smoker! I dont drink much! C'mon..

 

http://www.weldingsuppliesfromioc.com

 

That link is one of the BEST suppliers I have found anywhere. Free shipping, fantastic prices, excellent poeple to deal with.

Share this post


Link to post
Share on other sites

I think I paid $580 for my LIncoln Mig SP125. It is about as small a machine as you want to weld thin to thick metal. I can weld 20gage sheet metal and over 1/4 inch metal. It does good exhaust welds, as well as roll bar tubing and flat stock steel.

 

Of course I use 75/25 Argon and I always keep two bottles on hand. I need to break out my Torch and play with brazing... Not done that in a while...

Mike

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×