An arc welding process that uses an arc between a continuous filler metal electrode and the weld pool to produce a fusion (melting) together of the base metal

The process is used with a shielding gas supplied from an external source without pressure.

Wire Feed

MIG = Metal Inert Gas Inert Gas= Inactive gas that does not combine chemically with base

or filler metal

MAG= Metal Active Gas Active Gas= Gas will combine chemically with base or filler metal

Advantages

Variety of Metals

All Position Welding

Quality Welds

No Slag

Low Spatter

Disadvantages

Cost

Not portable

Easy to lack of fusion

Not suitable for windy conditions

Only for clean Base Material

Cover all skin to prevent Radiation burns

Cover hair to prevent sparks setting hair on fire

Wear ear plugs to protect from noise and burning ear drums with sparks

Use a 14 shade welding helmet to protect eyes

Wear safety glasses at all times

Make sure pants pockets are empty

Power Supply Direct Current Electrode Positive (DCEP)

(Electrons flow from – to +)

Wire Feeder Electrical mechanical device that feed required amount

of filler material at a constant rate of speed

Welding filler electrode Small diameter consumable electrode that is supplied to

the welding gun by the roller drive system

Shielding Gas Gas used to protect the molten metal from atmospheric

contamination : 75%Argon (inert gas) & 25% Carbon Dioxide most

common gas used for GMAW

A. Hand wheel

B. Flow meter

C. Wire spool

D. Wire

E. Feed roll tension

F. Voltage meter

G. Wire speed meter

H. Wire speed adjustment

I. Voltage adjustment

J. Power switch

K. Gun cable

L. Gun

M. Ground clamp

N. Ground cable

O. Feed rolls

P. Wire guide

Q. Wire overrun

R. Safety nut

Plug ground wire into (Neg) Terminal

Plug Wire Feeder into (Pos) 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)

Min. Arc Control

• Soft Arc • Thicker Materials • Deeper Penetration • More Fluid Weld Pool • Flatter / Smoother Weld • Reduce Spatter • Stainless Steels

Max Arc Control

• Crisp Arc

• Thin Materials

• Arc Stability On Open Gaps

• Convex Weld Bead

• Increased Spatter

• Colder Arc

• Improved Weld Pool Control

Set Volts See Chart for proper setting

Set Wire Speed See Chart for proper setting Increase wire speed = Increase amps Decrease wire speed = Decrease amps

Set gas flow See Chart for proper setting Pull trigger to get gas flowing then adjust regulator

Hold tip 1/16” to 1/8” from work piece

Angle of tip should be 10-15°

Can push or pull bead Pull (preferred)

More stable arc Less Spatter Deeper penetration

Push More spatter Less penetration Good cleaning action

Possible Causes Corrective Actions * Drive Rolls in Poor Condition *Tighten, Clean, or Replace

Drive 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

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 Contact Tip to Work Distance

Possible Causes Corrective Actions * Insufficient Amperage *Increase Amperage

* Improper Travel Angle * Use Less of a Drag angle

* Excessive Electrical Stickout * Decrease Contact Tip to Work Piece Distance

* Weld Joint Too Narrow * Increase the Opening of the Weld Joint

GMAW Process Parameters

Steel Material .035” wire Short-Arc Mode

Thickness Gas 75%AR-25%CO2

Amps Wire

Speed

Volts

1/8” 18-19 140-150 280-300 23-24

3/16” 18-19 160-170 320-340 24-25

1/4” 21-22 180-190 360-380 24-25

5/16” 21-22 200-210 400-420 25-26

3/8” 23-24 220-250 420-520 26-27