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Mig Welding. Presentation, Pictures, Graphics and Content Produced by: Terrance K. Orr M.Ed. Assistant Professor Collision Repair Technology Utah Valley University 2007-2008. Why Mig Weld?. Wire-feed Fusion Welding Process. Minimizes the loss of strength in High Strength Steel. - PowerPoint PPT Presentation
Citation preview
Mig Welding
Presentation, Pictures, Graphics and Content
Produced by:
Terrance K. Orr M.Ed.Assistant Professor
Collision Repair Technology
Utah Valley University
2007-2008
Why Mig Weld?
Wire-feed Fusion Welding Process. Minimizes the loss of strength in High
Strength Steel. Minimized Metal Distortion. Vehicle Manufacturers demand its
use. Faster Procedure.
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Mig Welding
Uses a constant voltage source.
Wire feed rate sets the current.
Continuous flow of shielding gas.
Continuous supply of wire.
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Mig Internals
Straight or Reverse Polarity.
Wire Tension Adjustment.
Continuous Wire.
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Electrode Wire Sizes
There are three common sizes of MIG wire. .035 .030 .023
.023 is recommended for collision repair work.
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Mig Welding Adjustments
Wire Feed Speed Voltage Continuous/Spot Distance from coupon Push/Pull
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Mig Welder Settings
Voltage Adjustment
Wire Feed Adjustment
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Welder Suggested Settings Each welder has
suggested wire feed and voltage settings dependant on the thickness of the material, the shielding gas, and type of wire used.
This is found on the lid of the welder.
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Tuning the Welder
Tune For Specific Metal To Be Joined Set Voltage and Wire Speed Make Sample Weld Readjust Settings as Necessary Practice the Push and Pull Technique
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Gun Technique
•Heat into Puddle
•Slower Rate of Travel
•Heat into Work
•Easier Burn Through
•Faster Rate of Travel
Pulling the Weld Pushing the Weld
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Weld Positions
Standard Flat Position.
Vertical – Start at the top and move down.
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Weld Positions
Horizontal – Used on vertical panels.
Overhead – Can be a difficult weld to master.
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Defects – High Heat
A voltage setting that is too high will result in holes melted through the panel.
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Defects – Good Weld
This is an example of a good weld. Look for an even bead without spatter, and an even heat affect zone.
Heat Effect Zone
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Defects – High Wire Speed
High wire speed will create a cooler weld with very little penetration and excessive surface bead buildup.
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Defects – No Gas
A weld without shielding gas will be porous and very uneven.
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Travel Speed
Travel Speed is another variable that can affect your weld quality. Too slow can cause excessive
penetration and burn-through. Too fast can cause excessive bead
buildup without adequate penetration. It is a combination of Travel Speed,
Voltage, and Wire Speed that creates a good weld.
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Defects – Speed too Fast
If the travel speed is too fast inadequate heat will create a tall bead with no penetration.
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Defects – Speed too Slow
Travel speed that is too slow will result in a wide bead with a large heat affect zone.
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Weld Penetration
Weld penetration should also be checked to ensure complete metal fusion without excessive heat.
This picture shows a good even ribbon of penetration.
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Weld Penetration
This picture is showing excessive penetration.
The weld puddle is literally falling through the metal and if left unchecked will result in a hole.
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Problem Solving
Clean The Metal Coatings Rust-proofing Grime Rust Don’t Grind off Galvanizing
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Problem Solving - Weld Fit Up The term Fit Up
refers to the preliminary alignment and securing of the panels to be welded.
Proper fit up can greatly enhance the weld quality.
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Weld Fit Up
Assure Good Fit Up Tightly Clamp the
Metal Using Locking Pliers
Grind Off Burrs Use Metal Screws Use Clecos
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References Miller Electric Mfg. Co. Education.
http://www.millerwelds.com/education/library.html, 2006.
Lincoln Electric Co. Lincoln Welders. http://www.lincolnelectric.com/, 2006.
Inter Industry Conference on Automotive Collision Repair. I-CAR Online Training. http://www.i-car.com/, 2006.
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