1. Intro To Basic Gas Metal Arc Welding

2. GMAW: Gas Metal Arc Welding Also known as MIG and wire feed welding
Best suited for high volume production welding
Has a higher current density at the welding electrode than SMAW
Unique because it has a continuously fed electrode
Most productive welding process
Also known as MIG and wire feed welding
(Metal Inert Gas)
Aluminum and magnesium are typical when only an inert gas is used.
When only Carbon Dioxide is used, manipulation of the welding gun is necessary.
Also known as MAG
(Metal Active Gas)
Carbon steel and stainless-steel welding when carbon dioxide ands or/oxygen is added to the inert gas.

3. Manipulation methods:
Can be welding by pushing or pulling the welding gun
3/16” or thinner
Push
Thicker than 3/16”
Pull (Deeper penetration)
Manipulation methods:
Zig zag
Step back
Semi circle
Drag
Circle (typically on thin materials like 16 gauge and pushing the gun is recommended)
Do not Circle on thick materials because it creates “cold lap” (When circling, always push your puddle up)

4. Gun Angle Variables Always start with a short “stick out”
10 – 20 degrees for pushing or pulling is typical. (We will use 15-20)
Variables
Always start with a short “stick out”
¼” – 3/8” to avoid cold start
When you start with a long wire sticking out, you decrease you are decreasing your amps…leaving a cold start.
Dictated by electrode type and diameter.
Amperage and Voltage
Work together
Never change one drastically without the other. (Miller Weld Calculator)
Increase or decrease in voltage effects amperage
GMAW machine can make up some, but when you are outside the range, it can not.
GMAW is constant voltage
Voltage should stay consistent
SMAW and GTAW are constant current
Maintains amperage setting
Large changes in voltage setting controls mode of metal transfer (type of arc)

5. Wire feed speed Electrode Selection Shielding Gas Voltage Setting
Hold trigger for 6 seconds, measure the length of wire and multiply by 10.
Also the Amperage setting
Electrode Selection
.035 is what we will be using
Shielding Gas
75/25 (Argon/CO2) is what we will be using
Voltage Setting
Short circuit
(what we will use)
Wire makes contact with the metal
Wire melts of thousands of times per second
Globular
Wire melts off in globules larger than diameter of wire and wire never makes contact with the material. (Not commonly used because the molten puddle is hard to control.)
Spray Arc
Wire melts of in tiny globs and the wire never comes in contact with the material
Can be run with wire speeds at 500 IPM
Arc burns hot enough welders often need heat deflectors on knuckles.

6. Other Cold Lap Consumable Shielding Gas
Bead width
10x the diameter of the electrode (.035 x 10 = .350)
Cold Lap
Lack of fusion
Consumable
Wire is consumable and becomes the weld bead
Shielding Gas
Protects the molten puddle like the flux on a electrode for SMAW
Pipe line is starting to use GMAW process more (tents over welding area)
Electrode extension during the welding process
Must maintain arc length
1/4 “ – ½”
Ideal 3/8 “
Electrode angle
Must be able to push and pull
Advantages of GMAW
High Productivity
Fewer stops and starts (tie ins)
Readily adaptable to automation

7. Weld #1 Disadvantages to GMAW “Cold lapping” or lack of fusion.
Settings 18 volts, 220 amps
Push
pull