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Mig Welder How To

Mig Welding How To Weld


mig welder

Perhaps you are there and you are thinking of getting your hands on your very own Mig welder.

So whether you have prior experience with Migs or you are green to welding, you are probably reading this because you want to get the hang of the welding process. 

How A Mig Welder Works

Ever heard of Metal Inert Gas (MIG) welding? Well, you are in the right place to explore the A to Z of MIG welding.

I bet you will be welding like a pro by the end of this content! 

How A Mig Welder Works / Repairs

styles of MIG welding torches Click Here

What is MIG welding?

First of all, let’s be clear what welding is.

This is the process of fusing metal parts by heating the contacting surfaces to the point of melting. 

So therefore an MIG welding process will then have two components.

There is the metal component which is a continuous solid wire electrode that is fed into the weld pool through a welding gun. 

The other is the gas component which is a shielding inert gas sent through the welding gun.

The gas acts to protect the weld pool from contamination.

For the metals to be joined, a discharge of electricity which later would be referred to as an electric arc is produced.

This is actually gas being electrically broken between the wire electric lead and the project.

The metal(s) being welded is heated till melting point allowing fusion.

roll of mig wire

Invented in the 1940’s, MIG welding was developed for welding non-iron materials and aluminum.

Because of its relatively faster welding time as compared to other welding procedures, it was then applied to steels later on.

Unfortunately, its use was limited due to the cost of inert gas.

Nonetheless, this was addressed several years later because Carbon dioxide (CO2), a semi-inert gas started being used. 

In the recent past, MIG welding was referred to as Gas Metal Arc Welding(GMAW), although this name was unpopular as most people didn’t use it frequently, hence making the initial name, Metal Inert Gas (MIG) be maintained. 

Today, because of the versatility high welding speed and relative ease of incorporating the process to robotic automation, MIG welding is the most common industrial welding process.

The Basics of Welding and Types

Welding is a very fundamental skill more so for the hardcore and also moderate enthusiasts. As a beginner, it’s important that you identify your needs in reference to welding and match them to the necessary welding skills. 

Before we hop onto the MIG welding bandwagon, it will do no harm to mention to you other common types of welding out there which include:

Inert Gas welding using tungsten (TIG)–Am tempted to call this the persistent brother to MIG. You see in place of the wire electrode in MIG that gets all used up as you weld it has a tungsten.

You have probably heard of tungsten from your light bulb classes. Yes, it is the wire that never burns out. TIG is well known to produce highly detailed and precise welds.

Stick Welding – in this process, an electric current flows in the gap between the metal and the welding stick which is also known as arc-welding electrode. It is the perfect choice for joint and mixed metal welding.

Unravelling the MIG welding machine

Remember how as a kid you would literally tear apart every toy you would get to figure it out?

Well right here we will take down this welding mystery and explore what really makes it tick, literally.

You would expect it to have different parts and we are going to delve into each part.


The welder

mig welder
mig torch spares

You would anticipate from its name that this component is important to understand.

You can take it as the container of wire to be incorporated into the material being worked on.

A spool of wires and a series of rollers is what you will find within the welder machine.

This is definitely a good to know because sometimes the wire feed gets jammed up. 

A tension nut is what holds the spool of wires in position.

Check on the nut tension so that it is just tight enough not to allow unravelling of the wire feed. 

However, the rollers will have a heck of a hard time pulling out the wire if the latter is held too tightly.

You would also notice how the rollers pull the wire from a larger wire roll, like a conveyor system of sorts.

So on what metal wire to have in or not, this choice depends on what metal is being welded.

For instance, an aluminium wire would be your loading choice if you are working on aluminum.

The MIG wire

Now that I have mentioned it, let us shed some light on this wire business.

Part of the job is to actually install the MIG which you would buy separately.

Red shoes go with a red belt so thick MIG wire for thicker metals being welded.

Of note is, thinner wires give better quality welds. So it goes without saying that a choice of wire diameter is crucial before cranking up the machine with the MIG wire.

A 0.35” wire is perfect if you are starting out and you can work on metals up to a thickness of 1/4”.

mig torch spares

The Gas tank/bottle

welding consumables
shielding mig gases

There is, of course the conspicuous container of gas waiting to shield some metal behind the MIG welder.

This tank contains the inert or chemically inactive gases used in the welding process. 

The wire in the welder is sent down a set of hoses once it passes through the rollers.

The charged electrode and gas are then carried by the hoses.

The hoses lead to the welding gun.

Now imagine your weld getting holes from being exposed to atmospheric gases.

Picture that decent piece of metal getting a nasty shade of brown or looking all splattered!

This is where the inert gases come in.

They prevent any reaction between the welding pool and atmospheric oxygen and nitrogen. 

MIG welding gives you gas options.

Argon or carbon dioxide (CO2) are the most popular. But you can get a mixture of both.

MIG welding with pure argon

It is only used for non-iron welding so you are thinking of metals like aluminium.

It is not used to weld steel (a refined form of iron) because it does not get through steel joints well.

This is due to its low thermal heat conductivity.

MIG welding with CO2 (Carbon dioxide)

It is a favorite because of its affordability.

You know how there is always something about the not so expensive options?

Well, for CO2 it would be the fact that it produces a lot of spatter and its pretty wide arc is not stable.

MIG welding with Argon Mix

This hybrid comes second to CO2 when you are considering cost.

The idea of combination for impressive results is a testimony combo! Why?

You get better penetration and minimal spatter because the arc is more appropriately sized.

welding gun

MIG welding with no gas?

Okay I want to introduce another concept now that we are talking gases. Heard of gasless wire welding?

Imagine what would happen if wind blew as you welded! Your gas shield will be done away with.

That is why there is gasless wiring a cool modification of MIG welding! Here an arc welding electrode turned inside out would be your filler metal. 

Flux components are rolled onto the wire and the chemical composition of the flux act as the shield.

The components include deoxidizers and vapor forming compounds that boost the shielding effect. 

Also the flux contains alloying elements that strengthen the metal. Now that’s what I call a bonus!

The Welding Gun

So this is where all the magic happens.

Okay most of it, but the fun magic.

Your eyes and skill will be spent on this bad boy. So the gun will not be a gun without a trigger! 

The trigger here works to moderate the wire being fed in from the welder and the electric current.

A replaceable copper tip guides how the wire comes on. A welder would have its specific tip.

Tips would go with the size of wire diameters you are interested to weld with.

No pressure here because this part would probably be already set up for you.

For extra protection the tip of the gun gets a ceramic or metal cup.

Protection is for the electrode (sorry tip) and it also directs gas flow out of the gun from the tip.

styles of MIG welding torches
styles of MIG welding torches

The Ground Clamp

welding earth clamp

This is the negative end that is the cathode, in the circuit and it wraps up the flow between the project, the welder and the welding gun. 

It can be clipped onto the metal welding table or directly to the metal being welded.

Be careful to work off any rust or paint or anything on the metal being welded that will prevent it from having good contact with the clamp.

Setting up the MIG welder & controls

By now, I do hope you have a good understanding of how each component works as mentioned earlier.

But if you want to make the welding process a walk in the park, then you certainly need to know how to set up each part. 

I will outline to you in the simplest way possible of how you can set up the machine with much ease and you will definitely be looking forward to fix up all that junk at your workshop, wouldn’t you?

Prepping the equipment

mb 25
mig rollers
mig contact tips

Of course you want to make sure that everything is in its happy place before you start firing away.

Your welding checklist would read the following:

1. Tight fitting of all wiring and cables

2. Right selection of electrode polarity. 

A direct current (DC) electrode positive is what you want for your MIG welding.

A careful look inside the MIG machine and you will see the polarity connections

3. Gas flow is set

Set the flow rate to about 20 to 25 cubic feet per hour once to flip the valves of the gas tank open.

Do check if the gas hose is leaking. A simple test of looking out for bubbles once you immerse the hose in soapy water should do.

A new hos should replace the leaking culprit.

However, know that the temperature of the weld pool will be reduced if you 
release too much gas.

Balance between high temperature and good gas flow is therefore key.

Here is a tip: Three inches from the tip of the nozzle, place your hand.

A sense of gas moving would give you the idea that your gas is on the go and just enough of it.

4. Ideal wire tension

5. Consumables looking good to go
Here you do basic welding grooming, you know, like discard any rusty wire.

Also, excess spatter from contact tubes should be removed. Oh and who wants to work with worn out contact tips?

Once you are certain that your equipment is in optimal condition, you can go ahead and start setting up

The welder

You need to ensure that the valve linked to the shielding gas is open and have at least 20 ft3/hr. flow through the regulator.

Check and confirm that the welder is on, and that the grounding clamp has been attached to your welding table or the metal directly.

It’s also important for you to have the right wire speed and power setting which we are going to expound on later on.

MIG Wire

Installing the MIG wire will play a huge role in the welding machine. In doing this, the wire can feed through the MIG gun and make its way to the weld pool.

Wire sizes

The welder usually comes with a role of flux cored wire which means that you may have to make plans to purchase some MIG wire.

You may consider choosing a thicker wire or a thicker metal. 

To add on to that, if you want the best quality weds, then why not crank up the machine on a thinner wire instead of having it really low on a thicker wire.

The guidelines below can assist you on how you can choose the right wire.

Just to emphasize, ensure that you check the door chart on the inside or the MIG welder in order for you to see their specific recommendations.

• 0.23” wire-this will the best option for you if you are using small welding machines and you want to weld thin sheet metal from 24 gauge to around 16 gauge.

• 0.3” wire-this usually accompanies the MIG welder and it’s a good choice for a sheet metal that is up to around 1/8”.

• 0.35” wire- this will be most appropriate for a job that is up to ¼’’ hence making it a good option for starters.

• 0.34” wire-this will be perfect for ¼” and above therefore making it suitable for industrial welding.

How is the MIG Wire Installed?

mig torch spares

You already have the MIG wire and wondering how you would install it without having any technical hitches.

Read the following steps carefully and you will get a hang of it.

open the cabinet

Ensure the cap has been unscrewed from the spindle then slide the wire spool through the spindle.

Also ensure that the MIG wire is facing the direction of the driver roll and is at the bottom of the machine.

Once the cap is loosened, the pressure release is then flicked open.

Nothing will happen if you are to press the trigger on the gun with this released.

Adjust the tightness by twisting the pressure roll.

Feed the MIG wire through the drive roll entry slowly and in doing so, make sure that the wire is not bent.

Place the cap on the spool of wire and ensure that the spring is in place before attaching the cap.

Otherwise, the spool will keep on rolling hence damaging the wire if you forget the spring.

Remove the MIG nozzle then bring its tip into contact with some pliers.

Start feeding the wire through the gun once you have pressed the trigger.

Finally, return the nozzle and the contact tip back to place and your MIG wire is successfully set up.

Nozzle and Wire Stick Out

From the tip of the nozzle you may be able to see some inches electrode that has not melted and it is peeping out. This is known the wire stick out.

Now what you want to hear is a sizzling bacon sound to know that the arc is set justright.To get this familiar sound, you want a stickout of about 3/8 of an inch.

Just in case you get to hear anything that does not sound like bacon hitting oil, your stickout is probably too long

Once you have fed the wire to the MIG gun you will notice that the shorter the electrode sticks out, the hotter the weld will be.

If the metal you are welding is really thin then you could have it longer than 3/8”, in case you are concerned with welding directly through the metal.

Make sure that the nozzle is kept clean and remove any spatter sticking to it, as a nozzle that has a spatter stuck to it may reduce the flow of gas to the paddle thus causing porosity.

If you want to prevent the nozzle from sticking, I would suggest that you apply some range of sprays and gels.

mig torch

Front of the machine

mig weld how to
welding earth clamps

The front of the MIG usually has a simple layout. There are two main dials that control the wire feed speed and voltage settings.

Voltage and Amperage

I had earlier on mentioned about power setting at the Welder section. So as a beginner, it is important to note that the voltage settings will determine the temperature and the height and width of the bead.

Variables such as metal type, how a joint appears, thickness of the metal, your position as you weld, shielding gas and wire diameter speed, determine voltage and amperage.

Look up welding machinery that is accompanied with a guide or chart to assist you set up the electricity controls. With time you will be fine-tuning like a pro and meeting your personal preferences.

Starting off with the thinnest metals, put the lowest voltage setting and then move up. This depends on how thick the metal is.

For light work an amperage of 130 can perform the job required.

Amperage of 200 minimum is for the heavy duty tasks. It gives better penetration. Some machine designs allow you to deliver welding at 200 amps and experience MIG welding with power equal to heavy duty stick welding.

An example would be the Miller’s Shopmaster 200, which at a 40% duty cycle can deliver 200 amps of AC. So you get welding for a continuous four minutes at 200 amps.

The welding process

We cannot talk about welding if we will not mention how you actually get to do.

I will not go splitting hairs with details. Am certain by now you are wielding the gun in your mind. Awesome! Let us get welding shall we?

– Run a bead

This is something you want to do if it is your first time welding.

This is not hard at all and in no time you will be getting metals together. 

First start with a straight line. Then get creative and attempt making concentric circles with the tip of the welder or you can try little zig-zags.

Your motion would be moving away from the top of the weld downward.

Think of it like sewing and the welding process will become a walk in the park.

Do a little welding in a spot then move to another spot then you can fill up afterwards.

Welding metal together

Essentially have the surfaces to be welded ground down at the edges.

Take the welder and go with your sewing motion across top of the seams .Ideally, weld from the bottom up but as a beginner assume the position you are comfortable with. 

A big bump of filler will be left on the welded surface and you can choose to grind it flat.

If you notice that the weld has not penetrated properly after grinding off the excess filler, you can increase the power and add filler wire to enhance penetration.

Some of the common problems you are likely to encounter include:

Not enough shielding gas leading to splattering of the weld. You can try turning up the gas pressure

Weld burning. This is due to high wire speed so do adjust accordingly

Welding gun spitting and not maintaining a constant weld. Holding the gun far from the weld would cause this.

Maintain a distance of ¼  of an inch from the weld.

Worry not though, with practice you will be cruising through your welding sessions in no time.

Advantages of MIG welding

• Easy to learn and set up

I have taken you through all the nitty gritties of how you can set up your welding machine by yourself and you can agree with me that the steps I have provided are super easy!

It takes you a very short time to set up and in no time, you are welding like a pro.

• Productivity

This has to be one of the best things that MIG welding has to offer. Imagine the time saved up by having to do all the cleanup, changing rods, brushing the weld or chipping away the slag.

This all goes a long way in increasing your productivity.

• Reduced Cost

Good thing about acquiring your own welder is that it is very affordable as you can purchase it for as little as $ 500.

The only expense you will make other than getting it is on some wire and gas then voila!

You have a perfectly working machine.

As you already know, with increased productivity, the welding costs will definitely be lower and that shall allow you to get more tasks completed.

There is surely no better way to run your small business with such a low budget don’t you think?

• Good quality

Since MIG weldings use shielding gas for protecting the arc from atmosphere, it results to having a good clean weld whereby there is no need to remove any slag.

Also being able to control the MIG hands because of using both hands helps a lot.

The other thing is that there is increased versatility brought about by the wire feeds and voltage setting.

Disadvantages of MIG welding

plasma cutter
welding shirts

• Sensitivity to wind

Unfortunately, the shielding gas which is used during the process could be easily blown away during the process of outdoor welding.

• Lack of fusion

MIG welding has the potential of for incomplete fusion especially since the welding may be done in low currents and when it is operated in short circuit mode.

~ Fast cooling rates

Since the welded metal is not covered with slag once the welding is completed, it will cool at a higher rate
• Shielding gas Bottles

The shielding gas bottles may take time to be replaced and they may get in the way during the welding.

• Safety and Precautions

Although MIG welding can be pretty safe, you might want to follow the following safety precautions as a first timer.

Please note that MIG welding produces a lot of heat and also lots of harmful light therefore to protect yourself against such you need to:

Get a welding mask as you will be exposed to extremely bright light which may burn your eyes and your skin just like the sun would.

Wear gloves and leathers that will protect you from molten metal splattering off at your working space.

The leathers do not only protect your skin from the heat produced but also from the UV light.

Wear cotton clothing as wearing plastic fibers like polyester and rayon may melt if they come into contact with the molten metal and that shall definitely burn you
Weld in a well-ventilated area. You do not want to inhale the nasty hazardous fumes from the welding process now do you? 

A mask or even a respirator will come in handy in case you are intend to weld for long.

Any last advice?

MIG welding is a favorite for all welding beginners and I say take on the challenge because it is going to favor you most definitely!

I hope the discussion above answers most of your queries on MIG welding and also excites the curiosity to get started. 

A couple of instruction videos and even watching someone else do it will complement the tons you’ve extracted from this read up.

From here I bet you will no longer be poring through another page of MIG welding for dummies but soaking up all the pro stuff.

So do not sit on this knowledge. Go get in your welding gear and sew some metal together.

Remember safety first, then afterwards, unleash the thrill of welding!