Transcript Heat Joining Process - Utah Valley University

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
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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

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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
Pushing the Weld
Pulling the Weld
•Heat into Work
•Heat into Puddle
•Easier Burn Through
•Slower Rate of Travel
•Faster Rate of Travel
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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
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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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