Gas Metal Arc Welding GMAW MIG Wire Disclaimer

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Gas Metal Arc Welding (GMAW, MIG, Wire)

Gas Metal Arc Welding (GMAW, MIG, Wire)

Disclaimer • “This workforce product was funded by a grant awarded by the U.

Disclaimer • “This workforce product was funded by a grant awarded by the U. S. Department of Labor’s Employment and Training Administration. The product was created by the grantee and does not necessarily reflect the official position of the U. S. Department of Labor. The U. S. Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership. ”

GMAW • Uses a solid wire electrode that is continually fed into the weld

GMAW • Uses a solid wire electrode that is continually fed into the weld pool • Wire electrode is consumed and becomes the filler metal • Weld pool is protected by a shielding gas • Produces high quality welds on all metals • Weldable in all positions • Very efficient process (high productivity)

GMAW • The GMAW process use power sources that are “constant voltage” using DCEP

GMAW • The GMAW process use power sources that are “constant voltage” using DCEP polarity • This type of machine allows you to adjust the voltage as well as amperage (current) • A constant voltage machine will maintain a consistent voltage regardless of the amperage setting • Constant voltage also means it will maintain a constant arc length (voltage sets or controls the arc length)

GMAW Voltage • Arc length determines how well the puddle or weld pool will

GMAW Voltage • Arc length determines how well the puddle or weld pool will “wet” (flatten) out • This will have the most effect on the height and width of the weld • Electrons flow from negative to positive • Fun Welding Fact: The curve in the wire is called the cast. This ensures a good connection with the contact tip.

GMAW Amperage (WFS) • Wire Feed Speed (WFS) on the wire feeder sets or

GMAW Amperage (WFS) • Wire Feed Speed (WFS) on the wire feeder sets or controls the amperage for welding • If WFS is increased, amperage is increased • When WFS is decreased, amperage is decreased • WFS is measured in inches per minute • Amperage has the most effect on penetration

GMAW Terms • Wire feed rollers- This part consists of 1 or 2 round

GMAW Terms • Wire feed rollers- This part consists of 1 or 2 round rollers that grip the wire and pushes it through the guides to the conduit liner • Guides- This part directs the wire to the conduit liner • Conduit Liner-Guides wire electrode to the gun to protect it and minimize kinking

GMAW Terms cont. • Gas Diffuser-Spreads out shielding gas as it reaches the nozzle

GMAW Terms cont. • Gas Diffuser-Spreads out shielding gas as it reaches the nozzle • Contact tip- Transfers current to a continuous electrode (wire) • Nozzle-Directs gas flow to weld and protects the contact tip and gas diffuser • Bird nesting-Tangle of wire in the drive rollers, usually wire is pushed out the side

Electrode “Stickout” • The length of unmelted wire (electrode) extending beyond the contact tip

Electrode “Stickout” • The length of unmelted wire (electrode) extending beyond the contact tip • Proper stickout is critical because stickout affects amperage • A longer stickout decreases amperage • A shorter stickout increases amperage • Typical short circuiting stickout=1/4”-1/2” • Spray transfer=1/2”-1”

Short Circuiting Transfer • Wire actually short circuits against metal many times per second.

Short Circuiting Transfer • Wire actually short circuits against metal many times per second. This creates the “buzz” sound. • Used for thinner metal – up to ¼” • Used in all positions 1 F, 2 F , 3 F , 4 F • 75% argon/25% CO 2 typical shielding gas • Voltage Range 14 -22 volts • Amperage Range 50 -250 amps, better known as inches per minute • Listen to the sound & look for the spatter

Shielding Gases • 100% CO 2 -reactive gas, not as stable (harsh) arc, deeper

Shielding Gases • 100% CO 2 -reactive gas, not as stable (harsh) arc, deeper penetration, more spatter, cheap, will not spray • 75% argon/25% CO 2 -less spatter, easier puddle control, good arc characteristics • 95+% argon/1+%O 2 mixes-more fluid puddle, good arc stability, less spatter, wider penetration