Mig welding(edit)
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Transcript of Mig welding(edit)
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