Weld Types - Plug Weld

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Weld Types - Plug Weld
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Plug Weld

• Plug welds are used to replace factory spot
  welds.
• The plug weld is formed by punching or drilling a
  5/16 hole in the outer panel to be joined.
• Duplicate the number and location of the original
  factory spot welds.

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Plug Welds on Rail

• Plug Welds are commonly used with other weld
  types such as the butt with backing as shown in
  this picture.

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Plug Weld

• With the example given you should have a basic
  understanding of what a plug weld is and where it
  is used.
• Print off the Plug Weld- Task Performance Sheet
• The next step is to tune the welder and perform a
  Plug Weld that will be evaluated visually and
  destructively.

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Preparing to Weld

• Select two 3x5 coupons.
• Punch a series of holes with the 5/16 metal
  punch.
• Place this coupon on top of the other.

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Plug Weld Techniques
Two Recommended Techniques
Start in center of hole and move around the edge.
Start circling on the edge and finish in the
center
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Practice

• Practice both techniques to find your preferred
  method.
• When you have a good weld move on to the next
  assignment.

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Assignment

• Using two 3x5 coupons punch a 5/16 hole in one
  corner.
• Position this coupon over the other as shown.

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Weld

• With your preferred technique make a plug weld
  that completely fills the hole.
• This weld will be visually inspected and
  destructively tested.

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Plug Weld

• A Good Weld
• Should completely fill the hole.
• Have a dimple in the center of the weld.
• Have a penetration ripple on the back of the
  panel.

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Using I-Cars WQT Gauge

• I-Car has provided a gauge to help in visually
  inspecting the welds for
• bead length
• width
• height
• penetration
• defects

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Using I-Cars WQT Gauge
Check the Minimum and Maximum Diameter.
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I-Car MIG Welding Gauge
Next check the bead height.
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Record the Results

• After the visual inspection is complete record
  the results on the task performance sheet and
  have the instructor verify your results.
• Now the destructive test will need to be
  performed.

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Destructive Weld Test

• Secure bottom coupon in vise.
• Bend top piece back and forth to separate
  coupons.
• A hole should remain in the bottom coupon.

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Final Weld Series

• When the welds pass the visual and destructive
  test observe the final voltage and wire speed
  setting.
• Mark the destructive test results on the task
  performance sheet.
• Complete your final plug weld series in the flat
  vertical and overhead position.
• Turn these in for final grading.

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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.co
  m/, 2006.