Spot And Plug Weld Nugget Size: Mitsubishi

Spot And Plug Weld Nugget Size: Mitsubishi

Did you know that many OEMs specify nugget size for spot and plug welds? This information is typically found within vehicle-specific repair procedures or can be found under general welding guidelines. Let’s see what Mitsubishi has to say.

Information on spot welds and plug welds can typically found in two areas of Mitsubishi vehicle-specific service manuals.

Spot weld information is located under: Service Manual9-Base of Body Repair Welding Electric Resistance Spot Welding. Here Mitsubishi provides a simple formula for determining the diameter of the spot welding tip to be used and a chart to determine the number of spot welds required based on panel thickness. In addition, the document also states the following:

  • "Make the spot welds at the center of the flanges to provide sufficient adhesion.
  • The number of spot weld points should be the same as, or slightly more than the number of original repair welds.
  • If the total thickness of the plates at the weld places is 3mm (0.12 inch) or more, use plug welding because spot welding will not provide sufficient welded strength.
  • When spot welding three or more panels together, if painted surfaces cause a loss of conductivity, make the welds at the same places as the factory welds. If this is done, extra welds will not be necessary, but if extra welds are necessary, switch to plug welding."

Plug weld information is located under: Service Manual9-Base of Body RepairWeldingGas Shield Arc Welding. Mitsubishi states the following:

  • "In order to prevent the formation of blowholes, fill in each hole completely in one pass.
  • Be sure the two panels are in perfect contact.
  • Be sure the penetration goes all the way to the bottom panel.
  • Plug welding is done by making holes 5-6 mm (0.2-0.24 inch) in diameter in one of the panels to be welded together."

Mitsubishi also provides information on making test welds on the same type of material to be welded and provides instructions on how to perform destructive tests for both spot and plug welds.

Following OEM welding requirements, including what nugget size is required, will help ensure a complete, safe, and quality repair.

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