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Learn To MIG Weld In A Flash

Sure, you want to learn how to MIG weld.  And why not?  It’s a skill that can come in handy practically every day of the week — especially when you’re doing repairs and fabrications. 
 
MIG delivers an excellent combination of speed and versatility, and it’s one of the easiest welding processes out there to learn.  In fact, a majority of the folks reading this article can learn to run a fairly nice bead with MIG equipment in almost no time at all.  All it takes is a little patience, a bit of concentration and a few hours of dedicated practice. We asked our friends at HTP to walk us through how to get started with MIG welding.

Mig Welding - Welding Sparks

MIG Explained

MIG stands for Metal Inert Gas and it’s a process of using electricity to melt and join together pieces of metal.

The procedure is also sometimes referred to GMAW (Gas Metal Arc Welding) and MAG (Metal Active Gas) welding as well as wire feed welding.  Compared to any other method of welding, MIG welding is, hands down, the easiest way to weld.  

MIG welding was developed for welding aluminum during World War II as a way to increase productivity.  Many different materials can be welded with a MIG welder, it is just a function of changing the welding wire (electrode) and the shielding gas.  In this article, the focus will be on welding steel.

In the most basic terms, MIG is sort of like using a crafter’s hot-glue gun.  However, with the MIG process, a continuous, consumable wire electrode (in place of a glue stick) along with a shielding gas are fed through a welding gun.  A short circuit is created, producing intense heat that melts the metal and allows the pieces to mix together and then fuse when cooled.

MIG welding is especially useful because it can be used to weld a wide range of metals (including steel and stainless steel, aluminum and cast iron) as well as braze steel.

In addition to being easy to learn and execute, MIG offers a number of other advantages:
         * It produces a cleaner weld
         * It requires less cleanup
         * It offers multi-position-welding capability
         * It provides the ability to easily join metals of a different thickness.

   
The Ins and Outs of a
MIG Machine

A MIG machine is made up of four basic pieces: the power source, a tank of shielding gas, a welding gun and a ground cable.  Each of these are crucial to the welder’s successful operation.

The Power Source— Located on the exterior of the power source are the operating controls for the welder.  Depending on the unit, these can include an on/off switch, welding amperage and voltage displays, spot and stitch controls and transformer adjustment.

Remove the cover and you’ll find what can be thought of as two separate machines. 1) The power supply side consisting of the transformer, rectifier and condensers.  2) The control side consisting of the circuit board, wire feed motor, main relay and solenoid valve.

Also located in the cabinet is the wire feed system.  This consists of a spool of wire and a set of rollers that deliver the wire to the welding gun.  The wire feed system is an extremely important part of the welder as a smooth, stable arc depends on a smooth, consistent wire feed.

The Gas Tank— The tank, normally located behind the cabinet, holds the gas  (100% Argon for aluminum or a mix of 75% Argon/25% CO2 for steel) that is used to shield the weld as you work.  The flow meter on the tank reduces the pressure in the tank (over 2000 PSI) to a usable pressure, allowing you to precisely monitor the gas flow.

Mig Welding Flow Meter

The Welding GunThe welding gun features a trigger that sends a signal to the machine to start the welding current, start the wire feed motor and turn on the gas.  A copper contact tip at the end of the gun takes all the welding current the machine produces and transfers it into the wire.  The tip is replaceable and must match the diameter of the wire you’re using.   The gas nozzle directs flow of the shield gas around the weld, protecting the weld from the atmosphere.

The Ground Clamp— The clamp completes the circuit between the welder, the gun and the metal being welded.

 

Start with Safety

When learning anything new, safety should be one of your primary considerations.  Overall, MIG welding is normally safe.  But because it produces a lot of heat and potentially harmful light, you should count on taking some safety precautions to protect yourself. 

Keep in mind that the light generated by MIG welding is extremely bright, so you’ll need a good welding helmet.  Today’s auto-darkening units are really preferable as they darken automatically when the welding arc is struck, eliminating the need to raise and lower the mask to see and allowing you to use both hands to weld.

A pair of heavy-duty gloves and protective leather gear is also important.  These items offer protection from any bits of molten metal that might splatter from the areas you’re working on.

Finally, only work in a well-ventilated area and always keep a fully charged CO2 fire extinguisher handy.

Welding_Helemt_and_gloves
   
The First Step

The first step in MIG welding is making sure that the surfaces you are going to weld are clean.  A few energetic swipes with a wire brush normally will do the trick.  A dirty surface could cause contamination, and create an unstable arc.  A very good rule to remember, is the more time spent cleaning, the less time spent welding.

Since the electrode and gas are automatically fed through the MIG torch, the basic technique for MIG welding is pretty simple.  Maintain a consistent position and orientation between the gun and the area being welded and the result will be a smooth, stable welding arc.

For best results, hold the MIG gun at a 45° angle.  Position your head so you can see the wire coming out of the welding gun.   Where ever you point the wire is where you will weld.  Try to maintain a constant arc length (the distance away from the work) and move with a constant speed.

Wig Welding - Angle
   

Let’s Get Started

We are using the HTP MIG 200 for this article. The MIG 200 will weld up to 3/8” and can dialed down to do thin sheet metal. First, make sure the power switch is in the “on” position and the grounding clamp is properly attached.    Make sure you have opened the valve on the tank and that you have adjusted your flowmeter to 15 to 25 cubic feet per hour.  Select the correct heat setting for the thickness of material you will be welding, and then using a piece of scrap metal, set adjust the wire feed rate.

There’s a relationship between the wire speed and the welding sound.  If the speed is set too low, you’ll hear a hissing noise and the wire will melt before it hits the surface of the work.  Gradually increase the wire feed rate until you get a nice, steady buzzing sound.  That’s where you want to be.

Remember . . . if the feed rate is too high, you’ll hear it spit and pop, like the wire is trying to melt below the surface of the welder.  So a nice, steady buzzing noise is what you should set the welder for.

HTP MIG-200  Welder
   

The Tack Weld

Start with a tack weld to avoid panel separation when you start welding.  Lay the edge of the gun right down on the work with the nozzle resting on the upper piece of metal.  Point the wire exactly where you want to start welding and pull the trigger on the gun.  This will start the wire feed as well as activate the flow of shielding gas and you can start welding.   For a tack weld, you want to weld for about 2 seconds – just long enough for a molten puddle to form and join the two pieces of metal together.  The tack welds should be two to three inches apart.

Tack Weld Photo


After the tack welds are completed, hold the welding gun at a 45° angle and get enough wire sticking out so that you can get it right where you want to start welding.  Resting the gun slightly on the work and maintaining the 45° angle slowly guide the gun along the materials you're welding in a smooth, constant motion.  You always want to keep the welding wire in sight so you can see exactly where you are laying the bead.

Control the bead width by moving the welding gun faster or slower.  You can reduce the heat input either by turning the heat up and moving the gun much faster.  Or, you can turn the heat down and move the gun a little slower.

   
Next, Stitch Welding

Stitch welding is just as easy.  Just turn the machine into the stitch weld mode, adjust the time and start welding.  In the stitch weld mode the machine is automatically welding and pausing. 

What the machine is doing is overlapping tack welding.  We’re just moving the welding gun when the machine pauses.  This type of welding helps prevent warpage and burn through because the gas helps cool the weld.  Stitch welding, in effect, is just a series of overlapped tack welds that join together to form one continuous bead – it looks  like a row of fish scales.

Stich Weld


Once you’re able to lay a bead and stitch weld, you can continue on to techniques such as plug and spot welding or other, more advanced procedures.  As we said earlier, it’s fairly simple to learn the basics of MIG welding. Then it’s practice, practice, and more practice.

If you want more information, HTP has an informative 52 Minute DVD that gives you a through the helmet view of MIG welding, so you can watch what has been described above on your Flat Screen!

Think of the preceding instructions as a guide to getting you started MIG welding.  Nothing beats getting a MIG gun in your hands and spending a bit of time working on some pieces of metal.

Source
HTP America, Inc.
800-USA-WELD
www.usaweld.com

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