How to Weld - MIG Welding

Picture of How to Weld - MIG Welding
This is a basic guide on how to weld using a metal inert gas (MIG) welder. MIG welding is the awesome process of using electricity to melt and join pieces of metal together. MIG welding is sometimes referred to as the "hot glue gun" of the welding world and is generally regarded as one of the easiest type of welding to learn.

**This Instructable is not intended to be THE definitive guide on MIG welding, for that you might want to seek out a a more comprehensive guide from a professional. Think of this Instructable as a guide to get you started MIG welding. Welding is a skill that needs to be developed over time, with a piece of metal in front of you and with a welding gun/torch in your hands.**

If you are interested in TIG welding, check out: How to Weld (TIG).
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Step 1: Background

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MIG welding was developed in the 1940's and 60 years later the general principle is still very much the same. MIG welding uses an arc of electricity to create a short circuit between a continuously fed anode (+ the wire-fed welding gun) and a cathode ( - the metal being welded).

The heat produced by the short circuit, along with a non-reactive (hence inert) gas locally melts the metal and allows them to mix together. Once the heat is removed, the metal begins to cool and solidify, and forms a new piece of fused metal.

A few years ago the full name - Metal Inert Gas (MIG) welding was changed to Gas Metal Arc Welding (GMAW) but if you call it that most people won't know what the heck your talking about - the name MIG welding has certainly stuck.

MIG welding is useful because you can use it to weld many different types of metals: carbon steel, stainless steel, aluminum, magnesium, copper, nickel, silicon bronze and other alloys.

Here are some advantages to MIG welding:

  • The ability to join a wide range of metals and thicknesses
  • All-position welding capability
  • A good weld bead
  • A minimum of weld splatter
  • Easy to learn

Here are some disadvantages of MIG welding:

  • MIG welding can only be used on thin to medium thick metals
  • The use of an inert gas makes this type of welding less portable than arc welding which requires no external source of shielding gas
  • Produces a somewhat sloppier and less controlled weld as compared to TIG (Tungsten Inert Gas Welding)
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batonas18 days ago

good thing pictured doesn't radiate uv, and still I feel awkward when looking, would feel more comfortable with welding mask tough :D

Jan_Henrik2 months ago

Nice, thank you!!!

ncblu5 years ago
i weld for a living. folks before you spend large amounts of money on a welder, make sure you are willing to spend the time practicing, thats the most important thing, practice, practice, practice. start running straight passes, no weaving or sewing or circling. when running a bead remember - where you point the tip is where the weld will be. if you're using gas, watch for porosity because you pulled the tip back too far and contaminated the weld. dont grind your welds - it's a bad habit, even if your welds arent pretty, they will be in time. speed is very important, constant steady speed. the welders you buy at harbor freight or walmart are fine for tack welding, but i wouldnt put it to use on a trailer or something that could have bad results if a weld cracks. if you run without gas you will get lots of spatter, even with anti spatter dip. prep is the most important, make sure your metal is clean and bevels should be between 25% and 50%. when making t-welds or perpendicular welds remember the metal will contract TOWARD the weld bead, not away from it ( i know this is contrary to popular belief and highschool science but it will happen ). never weld in a down direction, never drag the bead like you would in stick welding, always be pushing the puddle in the direction you want to go. most of all practice, practice, practice
HI There Can you tell me how close i should hold the tip from my work.
I usually Lay the tip on the metal and angle it.
For solid wire you want the wire to stick out about 1/4 to 1/2 inch, for flux cored wire you want a 1 inch stickout.
I agree on all points except for the grinding of the welds in my line of work (chassis fabrication) grinding the welds to make a flat billet style appearance is mandatory as long as the weld was properly prepped and is not over finished there will be no ill effects.
Thanks for that "pushing" the weld info  I've been trying  to drag the weld. Not working very well either.  Probably not my only problem however. As I mentioned before all I've ever done is stick welding.
So what brand of mig welder would you recommend looking at? I'm a carpenter but my next job has a good amount of steel involved.
2nd that - they're worth every bit you pay for them
its kind of hard to tell you exactly what type. I use miller welders at work because they are industrial grade and allow for mig/tig/stickwelding in one unit. they use gas shielding and are 3 phase units. the best way to decide is to try this link at miller under the product menu, you'll see smart select, they ask you a bunch of questions to help you decide. once you found the type and specifics that will give you an idea if you want to try another brand. it all depends on the type of metal your welding, the size of metal, available supply voltage, will you want to use gas or gasless and the size wire you want 0.16 or 0.32 is best. the units at walmart and home depot are ok and they can be used in either gas or gasless mode but using gas shielding is always better, if you go gasless you will use flux-core wire and it doesn't work very well on thicker metal and it spatters alot. hobart makes a pretty decent portable welder but they're pricey. lincoln makes good welders also. as for helmets, what do you want, automatic or standard. i would go to a welding shop for a helmet, the ones at the hardware stores that you can get for 99 bucks are only going to give you sore eyes after a little while, they just aren't that good. i use both kinds, automatic for short welding and my standard helmet if I'm gonna be running passes for the next few hours continuously ( stay away from gold plated lenses in your manual helmet, if the gold gets scratched the UV will pas right through and burn your retina's) get a good pair of gloves that aren't tight on your fingers. while you're at it pick up a good chipping hammer and wire brush from a weld shop- the ones at the hardware store wont last and grab a container of nozzle dip, some spare tips an extra spool of wire and a pair of welpers ( pliers) i know it sounds like alot but it really helps make the welding go smoother and makes for cleaner better welds in the end

hope this helps
ncblu ncblu5 years ago
one more thing, if you want to make a living as a welder, do not weave or circle or sew - you likely wont make it through to morning coffee break. also be prepared to weld out-of-position, this is welding on any surface that isnt sitting flat on a table ( which actually is harder to do properly than it sounds ). you might be welding upside down with hot metal dropping in your shirt.
joshr12310 months ago
Your amperage was too high and slow the speed
Spudmuffon1 year ago
Check and adjust tension you should be able to squeeze the wire and prevent it from moving while not causing any kind of bird nesting by the drive rollers
Spudmuffon1 year ago
Except for all the splatter on the nozzle clean that up I would rather knock it out with a round file but a screw driver, small pry bar, scribe, pliers will work.
Spudmuffon1 year ago
When grinding run parallel to the work not side to side save that for corner sanding with a 9in. Take the welds down to about 3/32 or so and have at it with the 9 in sander you will have much nicer results
Spudmuffon1 year ago
Honestly leathers are overrated if you are going to be welding day in day out 10-12 hours a day then yes they are wonderful the average person no long sleeves made from a non melting cloth will suffice
jjjwat1 year ago
my question is just about the wire.....canu use meg wire for jewlery making safely?
mtudge1 year ago
MIG welding is one of the most popular forms of welding used along with TIG welding, and it is personally one of my favourite welding methods. Thanks for sharing this article and BTW a great welding company is -
louis853 years ago
We are a professional manufacture&exporter of all kinds of welding machine,plasma cutters and battry chargers in China,if you need economical MIG welding mahice,please contack me
Taizhou Genteck Electric Co.,Ltd.
Add:Eco.&Ind.Development Zone,Wenling,Zhejiang,China.
Office Phone:+86-576-86088668
Fax Number:+86-576-86088558
Online service: MSN:,
Yeah, don't buy their stuff.

They don't even have the proper data for their equipment on the website, all they are are cheap Chinese Knock-offs of ESAB equipment.
Most Chinese factories don't have a data base for the website, many of them even don't have a website, they only produce the cheap machine.And the reason the machines are cheap: lower costs of blue-collar workers, no extral cost for any other "useless and expensive " workes ( an IT crew for instance) at all
Calling a worker who makes vital information easily available to prospective customers "useless and expensive" is pretty short-sighted.

There are a whole range of factors that effect the price for this equipment. We could debate that concept all day. The fact remains that this equipment will be of lesser quality.
No, we don't have to debate, yes, many of them are lesser quality.
However, the difference between the quality is much more smaller than the difference between prices,that is why there are still so many people buying them.
Your are absolutely right about the "short-sighted" too, many factories are used to do the domestic trade, by which they can take the customers directly to the factory, to see the equipments,to get all information in need, they don't have the foresight of international trade, but the profit of international trade is so enticing that they still make the way to do it.
If you have the chance to come to China and see the factories, you will understand all I am saying.
You're just looking at the initial cost difference. Not the added costs in the long run. You can't sue a company in China if the welder ends up breaking after two days, or worse hurts someone.

Honestly I have no desire to go to China. Not until the country cleans up it's act on an industrial level.
When I said "lesser quality",it definitely doesn't mean that bad, the quality you were saying is back to the 80's ,that is a long time ago. The truth may hurt your heart a little bit: many parts are produced here in China, only reassembled to an unit then marked as "made in ***"
The factories don't have the foresight to do the international trade, and you ,sir, don't have enough experiences to judge.Bias blinds people.
You know what also blinds people? Industrial Grade Glycerine being marketed as Medical Grade Glycerine That was in 2007. I have no problem being biased, China as a country has done nothing to remove that bias.
Bahahaha you spelled battery, machine, contact, and machines wrong :D Lol Fail
Sort you English grammar out before laughing at anyone else friend,as you are make a fool of yourself !!
amoroso824 years ago
I recently found the need to get a MIG welder to do some repairs around here, since I have never used this meathod of welding before I got a book and began to read up on this. Now I saw this article in Instructables that has raised some questions.
 I purchaced an 120 amp welder from Harbor freight as I am not going to use this machine to do structural welding I got their middle one. ( there is one cheaper and one more expensive) I guess since I was buying crap I didnt want cheap crap.  Any way they said that there is no need to use an external source of inert gas even though the machine is set up for it, I was told that I could use wire that has flux or some material that produced inert Gas while you are welding. Is that an inferior way to weld?and do I need to get this bottle?
 The reason I asked this is because I have read almost through this whole article and the writer has only mentioned the flux core wire once. I got this thing because it was less expensive than a buzz box and I can weld thin metals easier but if I have to shell out more spondulix for gas bottles and gauges the price can go up dramaticly.
If you use flux core wire, there is no need for shielding gas. However with flux core wire, you can only weld mild steel. Flux core wire can be used on any MIG welder, you just have to have the polatity reversed than you would for if you were welding with shielding gas. (usually easily done by flipping a switch or reversing the gound wire and the drive motor wire on the machine. think car battery terminals. your manual should cover how to do this on your machine). The advantage of flux core welding is that you get deeper penetration with the same amount of current than you would with your machine set up to use shielding gas with that same amount of power. Also, flux core is better for use outdoors where there may be a breeze that would otherwise blow your shielding gas away. In flux core welding, the flux is inside the wire, and as the wire burns, the flux creates a shield around the molten metal, protecting it from oxygen, which would otherwise contaminate the weld and make it weak. The disadvatage however is that it produces a lot of spatter, and the welds don't look as pretty either. BUT it does do a better job of penetrating rust/paint better than it would if you were using an external shielding gas. (although, you're really supposed to remove any rust/paint first). You do not have to buy a bottle of shielding gas or regulator if you weld with flux core only, but I'll tell you right now, it's a LOT easier to get good looking welds if you use shielding gas. As for what gas to use, for aluminum you have to use 100% argon. For mild steel, you can use CO2, Argon, or a 75%/25% Argon/ CO2 mixture. 100% Argon will give you the best looking weld, CO2 will give you the best penetration if you're welding something thick, but generally what is recommended is is the CO2/Argon mix, since overall it combines the best of both worlds. However it is slightly more expensive the the other two. As long as you want to weld mild steel, you don't HAVE to use shielding gas, so long as you use flux core wire. But if you want to weld stainless, or aluminium, or get really clean welds on steel, you'll need gas. On a side note, if you DO weld aluminum, you'll have to get a teflon liner for your welding wire hose. Otherwise, since the aluminum welding wire is so soft, it will get bent or caught up in the hose causing what's called "birds nesting". hope I answered all of your MIG questins. Happy welding, bro!
LIAR ALWAYS USE A GAS. i weld mild steel high heat with flux core all day and i use argon. without it i couldnt weld.
Wrong. You can indeed weld stainless steel with flux cored wire.

also switching to U-groove drive rollers will help feed aluminim wire more effectively.
Technically speaking alot of Flux cored wires produce better quality welds than solid wires do. They do have drastically different techniques though.

flux cored wires require longer electrode stick outs and faster travel speeds. Also, you'll need to use a slight drag angle instead of pushing.
Wow, I did the same thing you had done and I am too getting on line and trying to find out a little info on my "220 VAC Dual MIG Welder". Luckily, I have a current 12 yr. experienced welder in the family. Yes, I could ask him any ?'s I might have and see if he could teach me the basics of welding but I couldn't ask him to do all of that if I haven't done any work on my own. So here I am, trying to find a little more detailed info on welding. I see you posted your response back in April, have you gotten anywhere since then? I'm sure you've gotten further than me, have you learned any tricks to the trade? Maybe, we can help each other out or maybe you could possibly find the time to help me out on where to go from here? I'm am eager to learn and would be most appreciative of any help. Thanks

wild_child2 years ago
I've welded or a few years now. I use to weld on mild steel and now i weld aluminum. (Sorry for any miss spells.) One thing learned is each welder is different and sometimes you need to try different welding styles.
ccarrico2 years ago
This is a good article to how to use a MIG and I think that you covered the points well, however I think that perhaps a better picture would be better for this article. Even thought you are wearing gloves while MIG-ing I know from experience that you must wear a jacket or a long sleeved shirt to protect your arms from the ultra violet light. Even from say 30 seconds of MIG-ing without anything covering your arms you can get badly burned like a sunburn.
tenfingers4 years ago
I am aware that the guard on a grinder sometimes gets in the way, but not enough to leave it off all the time!
Work safe, use the guards that the tools come with.  If they weren't necessary the manufacturer wouldn't have put them on.
If it's in the way take it off, but replace it when that part of the job is done.
Grinders are made to remove hard metal by abrasion. Imagine how well they will work on soft flesh!
and it goes without saying, when you shut the grinder off, stop the disc, using either the piece that you just finished grinding, or the metal table it doesnt matter what, make sure it is not moving

i only bring this up because i just finished taking a formal MIG welding class, and another student tried handing me a grinder, abrasive disc first, while it was still spinning,
after telling him to stop the wheel and to never do that again, he tried to tell me that i was ok, because i was wearing leather gloves and a leather sleeve over my welding jacket,

bottom line: pay attention and be safe, and as toyotero said use your brain, especially when others dont
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