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).

Step 1 Background

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)

Comments

[TheExpert1]

MIG welding is useful because it can be used to weld many different types of metals like carbon steel, stainless steel, aluminum, magnesium, copper, nickel, silicon bronze and other alloys. Great post you have made. Thanks for sharing interesting stuff.

stainless steel manufacturers

[wild_child]

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.

[ccarrico]

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.

[tenfingers]

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!

[Jeffrey G C]

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

[toyotero]

This is a great instructable on the mechanics of welding.  Good work. 

I must say that I believe that every "intro to welding" written should cover more safety that was included in this one.

For example, readers should know that using a grinder without a guard involves some risk.  I've done it to get into an area where the guard hindered me, but I was very careful when I did it and I replaced the guard immediately afterward. 
Guards are your awkward friend that can save you from serious injury.

Most angle grinder injuries come from people getting metal particles in their eyes because they didn't wear proper safety gear.  On occasion, the grinding/cutting wheel can snag and kick up or back toward your body... or more explosively the wheel can break while spinning 10,000 RPM and send pieces fly with substantial inertia similar to a grenade's shrapnel.  The grinding wheel or it's pieces can go through thick clothing.  The grinder guards can stop these particles and pieces from flying at your body or prevent contact between the wheel and your body, but not if the guard is sitting on the shelf.

Here are a few documented grinder injuries on a medical website.
http://www.head-face-med.com/content/4/1/1

One other hazard that must be mentioned in regards to welding are due to the materials involved such as metals, metal coatings and solutions that might be used to clean the metal to prep for welding.  Everyone who owns a welder should familiarize themselves with these dangers. 

For example, common brake cleaner might be used to clean oil or grease off of metal before welding.  But if a drop is left on the metal, welding near it will turn it into phosgene gas which is a gas that was used to kill soldiers in WWI trenches.

http://www.brewracingframes.com/id75.htm

http://www.osha.gov/doc/outreachtraining/htmlfiles/weldhlth.html

I don't mean to try to scare anyone with these stories, I just want all my instructables associates to be aware of how to do it safely by identifying the dangers.  Welding can be done with complete safety and is a very fun and rewarding hobby if proper precautions are taken.

Have fun and be safe. Use your tool guards, use sufficient ventilation and always use your brain.  It is the most powerful tool we have to create new things and to keep ourselves safe.

Toyotero.

[NerdMaster]

I don't think you're scaring anyone. This is all common sense stuff that people choose to ignore. It's our God-given right to be unsafe in our garages. If you ever saw me weld, you would have a cardiac infarction on the spot.

[The Dark Ninja]

Thanks buddy, now I cant un-see those guys' faces.... HOWEVER, I am going to buy a faceshield here very soon and make sure my grinder has it's guard still on it. (A friends grinder actually, but still..)

[wayne_carlot]

You just scared the sh$t out of the learners.
Don't you have anything to do.
Breath some of that gas....breath deeply.

The rest of you, use standard safety procedures, You'll be OK.

Have welded for a long time, in big sheds, in the middle of nowhere, under water....etc  etc,

This is a good course, read it and "Ask lots of questions",

I don't think the bloke who's running it will care, Lots of fresh content gives you good google ratings...enjoy..:-)

[nail face]

 man youre gonna give me nightmares

[louis85]

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[Mathias Re'eh]

Bahahaha you spelled battery, machine, contact, and machines wrong :D Lol Fail

[msw100]

Sort you English grammar out before laughing at anyone else friend,as you are make a fool of yourself !!

[brandon_a_boyer]

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.

[welder.net.au]

MIG welding is useful because it can be used to weld many different types of metals like carbon steel, stainless steel, aluminum, magnesium, copper, nickel, silicon bronze and other alloys. Great post you have made. Thanks for sharing interesting stuff.

[BornOnFire]

In regards to Gas Tank Regulator Valves, An oxygen setup should always be opened completely so as to seat the stem of the valve against the packing. Failure to seat the internal stem's packing will likely cause a leak-resulting in a potential large scale explosion. The potential of a leak is more common than one would think. Imagine your garden spigot that you water your pansies with. Open it all the way and it usually works fine. Turn it a just few times and, usually, it drips-not a big deal. It's just a little water right? Apply this situation to your stuffy garage. You are welding a few things and the phone rings. 30 minutes later, your garage is a blasting cap just waiting for ignition. You get back to your work, strike an arc, and all of a sudden, you see a white light and your late grandmother welcomes you "Home" into God's kingdom. Now, we all would like to see Grandma again but I'm sure she can wait a few more eternities before you show up. Now, I'm not saying all regulator setups will blow you into grandma's arms again, but the Oxy-Acetylene setups are potential fatalities- now you know.

[Lorax98]

The "shield" gas is exactly that, a shield. It prevents gas molecules from the atmosphere from reacting with your molten metal. The term MIG stands for Metal Inert Gas; Inert- as in nonreactive. It is actually the Carbon Dioxide in the atmosphere that is the real problem.

[brandon_a_boyer]

Sorry, Incorrect, it's the oxygen that is the real problem, CO2 is commonly used as a shielding gas.

[amoroso82]

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.
                                            Michael.

[brandon_a_boyer]

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.

[Rollin 007]

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

Rob

[Sexy_Beast]

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!

[brandon_a_boyer]

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.

[Mr. space]

it works without shielding gas too. it reqires practice...
the only problem is oxidation. after the weld you must grind and protect against rust.

[brandon_a_boyer]

Wrong, using solid wire without shielding gas will also cause sub-surface porosity.

[ncblu]

welding sounds...... when i run hardwire, i can prep it to a point where you hear nothing, the only time you hear bacon sizzling is if you're running fluxcore or your metal isnt clean.

[brandon_a_boyer]

Wrong, whenever you run short circuit transfer you should hear that sound.

[magworks7]

This information I am giving may be a little advanced,but may help.There are 3 different types of wire transfer-(wire to parent metal) when it comes to running MIG. Static Transfer-(Bacon Frying Sound),Globular Transfer-(Some Sound),and Spray Transfer-(No Sound).The way you achieve each type of transfer is by adjusting your voltage control from lower settings-(static) to higher levels-(Globular),Highest voltage tolerance-(without burning back to your tip) will achieve your spray arc.What type of transfer used is determined by what the thickness is of the metal your welding on,and your rate of travel speed. When you are using a solid wire,and using a spray transfer,I would highly recommend using 95/5 gas-(95%argon,5%oxygen) as well.This gas will help you run a bit hotter,and will help you produce a better weld by bringing more impurities of your parent metal-(work piece) to the surface. On a personal note,I agree with ncblu. -Adding a comment,...a properly done finishing pass (at times) can improve the final overall appearance of the weld job without negatively affecting weld quality .

[brandon_a_boyer]

Gas valves on non-fuel gases should always be opened all of the way, bonnet type valves can leak if not totally opened or closed.

When you set up a GMAW there are two settings, Wire feed rate, and Voltage (voltage is not the same thing as power)

overpenatration is a result of either incorrect settings, or incorrect travel speed.

Stringer beads are always preferable over a weave, weaving can cas porosity and incomplete fusion

lack of penetration does not always mean your settings where incorrect, it could also be a result of poor technique or of inadequate root opening.

[massmale99]

Hi all I am a non pro welder but to answer the question about getting shocked
from touching the table or any part of the pieces to be welded together no shock will occur just do not touch the bare welding wire and the tip with bare hands as you will feel some current and the same as when putting new wire in the machine don't touch the machine and any bare metal wire part when loading a new roll
especially around the roller feed as you will feel current again. I have been bitten a few times it is not at all very uncomfortable but it is still a little shock that surprises you and always do wear welding gloves not some cheap leather gloves real welding gloves they are thicker leather and have a longer cuff that protects your arms and wrist from getting flash burns from the arc and if you mess up and touch the hot welded metal been on the receiveing line a time or 2 not thinking and just reaching will get you a good burn and do always use the welding mask no blind welds save your eyes from sparks and arc flashes is a must there are a ton of other things but you will learn as you go
weld on dudes happy happy joy joy

[salemsgt]

I just came into possession of a Chicago Electric 90Amp wire welder, non-gas. I have no operations/ owners manual. Does anyone know where I can get one? And, I have heard of a spray that helps limit spattering, what is it and where can I get it? Yep, I'm a rookie, just trying to learn. I'll appreciate any help anyone may offer. Refer to [e-mail] Thanks a million

[warstan]

Pam works well and its cheep.

[pfred2]

Download manual here:
http://www.harborfreight.com/cpi/ctaf/manuals.taf?f=form&ItemID=98871

You can get anti-splatter spray at a welding supply house. I have some, never use it.

[popscott3]

I really want to weld but I am 13...Is it reasonable to weld at this age?

[Suzuki_Professor]

Absolutely! I learned at about 12 years old. I grew up in a rural area and learned stick welding through the 4H program. It was a very useful skill on the farm.

If you are old enough to respect dangerous equipment, and have have reasonable eyesight and fine motor skills, you are old enough to learn to weld. That means almost every well-behaved and responsible 13-year-old is ready.

Best wishes in finding a teacher!

[popscott3]

Thanks!

[Eviil~~PikmiN__{7}]

im pretty sure that mig is ark welding because it makes an arc flash, thats part of the reason u need the helmet. stick, tig, and mig i think are all ark welding

[mindboggld]

it is a combination of gas and arc welding
I am taking shop class right now

[mindboggld]

It uses a filler metal that is fed through the gun kinda like a hot glue gun. The arc of the filler metal and the gas melts the metal to fuse it.

[rivetgeek]

Heres an old welders trick for mig spatter, cooking spray. Just spray the whole area with pam or some sort of non-stick cooking spray and the tiny beads wont solidify on the metal because they vaporize the spray on contact with creates a tiny gas shield under the bead as it cools. As an added bonus, welding now smells delicious.