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Gas Metal Arc Welding (GMAW)

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Presentation on theme: "Gas Metal Arc Welding (GMAW)"— Presentation transcript:

1 Gas Metal Arc Welding (GMAW)

2 GMAW Gas Metal Arc Welding MIG ( Metal Inert Gas )
MAG (Metal Active Gas) Wire Welding

3 Proper Attire

4 What is GMAW? Gas Metal Arc Welding MIG - MAG Welding
MIG = Metal Inert Gas MAG= Metal Active Gas Solid Wire with External Shielding Gas DCEP (DC+) Polarity 2

5 LIMITATIONS: ADVANTAGES: All Position Welding Quality Welds
Little to No Slag Low Spatter Variety of Metals Various Material Thickness High Efficiency High Radiated Heat LIMITATIONS: Cost Portability Outdoor Welding Clean Base Material Potential for Cold Lap Potential for Undercut High Radiated Heat

6 Identify Major Components
Power Source, Wire Feeder, Shielding Gas, Electrode Wire, Gun

7 Power Source Converts Primary ( Outside ) Power To Secondary ( Useable ) Power DCEP Direct Current Electrode Positive / Reverse Polarity DCEP = Lower spatter levels, Deeper Penetration levels

8 Wire Feeder Delivers Wire To The Weld Pool At A Very Constant Speed
Wire Feeder starts gas flow, current, wire feed Wire Speed Is Measured In Inches Per Minute

9 Shielding Gas To Shields The Weld Pool Form Contaminants That are In The Atmosphere Stabilize The Arc Helps Regulate Penetration Argon 75% - CO2 25% (C-25) 75-25 is used in the Lab Show Flow meter over the ELMO

10 Mig GUN Trigger Liner Contact Tip Diffuser Nozzle
Show parts over the ELMO

S = SOLID WIRE 6 = CHEMICAL COMPOSITION Wire Diameter Range (.025” ”) Copper coated vs. non-coated wire

12 Starting the Arc

13 Electrode Stick Out - ESO
Sheet ESO = 3/8 - 1/2 inch Plate ESO = ¾ - 1 inch

14 Bead Initiation

15 Bead Manipulation

16 Travel Angle

17 Bead Termination

18 Modes of Metal Transfer
1. Short Circuiting (Short Arc) 2. Globular 3. Spray The welding machine automatically selects mode of transfer dependent upon settings & variables. Type/mix of shielding gas Electrode diameter Voltage ESO 5

19 Short Circuiting Droplet Forms Droplet Shorted Metal Transfers
Fuse Forms Arc Re-established Low Cost Deep Penetration Less Spatter More Fluid Weld Pool 9

20 Globular Arc Initiated Large Droplet Forms Projected into weld pool 17

21 Globular Advantages Deep Penetration High Deposition Low Cost Gas
Limitations Excessive Spatter Flat / Horizontal Position Only 16

22 Spray Arc Initiated Point Forms on End of Electrode Wire
Numerous tiny Drops Form the Weld Pool 100% Argon 21

23 Spray Advantages Limitations Smooth Weld Bead Potential Undercut
Deep Penetration High Deposition Little to No Spatter Limitations Potential Undercut Higher Shielding Gas Cost Flat / Horizontal Position Only High Radiated Heat 20

24 GMAW Process Parameters
Steel Material ” wire Short-Arc Mode Thickness Gas 75%AR-25%CO2 Amps Wire Speed Volts 1/8” 18-19 23-24 3/16” 24-25 1/4” 21-22 5/16” 25-26 3/8” 26-27

25 Determining IPM without readout
Cut shielding gas Pull trigger & count to 6 Measure length of wire Multiply x 10

26 Wire Burnback Wire welds itself to the tip
Possible Causes Corrective Actions * Drive Rolls in Poor Condition *Tighten, Clean, or Replace Rolls * Excessive Welding Voltage * Reduce Voltage * Insufficient Electrical Stickout * Increase Contact Tip to Work Piece Distance * Contact Tip in Poor Condition * Clean or Replace Contact tip * Spatter on Contact Tip * Remove Spatter

27 Burnthrough Hole burns through base metal
Possible Causes Corrective Actions * Excessive Amperage *Reduce Amperage * Improper Travel Angle * Use a Push Angle *Travel Speed Too Low * Increase Travel Speed * Insufficient Electrical Stickout * Increase Distance

28 Repairing Burn through
Turn voltage slightly down Extend ESO to ¾” Small tack welds in a “star pattern” Allow metals to cool sufficiently

29 Incomplete Penetration
Toes should tie into metal 1/8 bead height max Possible Causes Corrective Actions * Insufficient Amperage *Increase Amperage * Improper Travel Angle * Use Less of a Drag angle * Excessive Electrical Stickout * Decrease Distance * Weld Joint Too Narrow * Increase joint opening

30 Lincoln V350 Setup - GMAW Plug ground wire into (-) Terminal
Plug Wire Feeder into (+) Terminal Select CV-Wire mode Hot start is not used Set Arc Control to “-5” -10= soft arc (for use with inert gases) +10= crisp arc (for use with CO2) (See Next Slide)

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