1. GMAW
GAS METAL ARC WELDING

2. GMAW
A welding process in which metals are joined by heating them with a welding arc between the base metal and a continuous consumable electrode.
Shielding gas or gas mixture is used to prevent the atmosphere from contaminating the weld.

3. TECHNICAL TERMS
GMAW
FCAW
MIG

4. GMAW Wire as electrode DC always used DCEP, DCRP is used
DCEN, DCSP seldom used
CV is used, current varies

5. FCAW
Similar to GMAW
Only difference is shielding gas is obtained from flux inside the electrode.

6. Advantages Longer Faster No slag Deeper penetration
Less training/ skill

7. Disadvantages
Costs
Some joints hard to reach
Rapid air movement

8. Short circuiting transfer
Contacts base metal
Some molten metal is transferred

9. Globular transfer Does not touch base metal Drops of molten metal
Large globs

10. Spray transfer Does not touch base metal Smaller globs
Drops of molten metal on base metal

11. Pulsed spray transfer Wire doesn’t neck down
Droplets form at a constant rate

12. Wire Feeder/ Welding Gun
Used to feed electrode wire to the welding gun
Feed is set on the wire feeder by welder
Make electrical contact with the electrode
Direct the shielding gas to the work piece
Remove heat from gun
Switch to start and stop welding

13. Finish Review Questions on Page 124 first!
Then turn to page 177 and do the review questions 1-20