Repair 7

How to MIG Weld Car Panels

Rusted or damaged panels on a car can be costly to repair at an auto-body shop. Instead, save money by repairing the panels yourself using a metal inert gas (MIG) welder. When welding car panels, choose between tack welding and seam welding. To avoid trapping moisture in the panel and rusting the metal, you should use butt joints instead of over-lap joints. Since car panels are usually carbon steel, you can weld them using a flux-cored MIG wire electrode or a solid carbon-steel MIG wire with the use of shielding gas.

Instructions

Preparation

1

Remove the panel from your vehicle, if possible, by removing the bolts holding it to the cars frame with a wrench.

2

Disconnect your cars battery to prevent faults in the vehicles electrical components if you are not removing the panel from the vehicle prior to welding,. You should also ground your vehicle by connecting jumper cables or a heavy gauge wire from the metal frame of your vehicle to an exterior grounding source.

3

Remove any paint, rust or dirt from the panel using a metal grinder or a wire brush. You will not create a stable weld if there is residual paint on the panel.

4

Clamp the metal pieces together in place to prevent them from moving while welding.

Tack Welded Joints

5

If you are tack welding the panel in place, increase the voltage for your MIG torch to a higher setting than you would normally use for a seam weld. You should also use a smaller diameter wire for the tack weld to ensure good penetration of the weld bead throughout the joint.

6

Place your welding torch between 1/8-inch and 1/4-inch from the welding seam and arc weld a 1/4- to 1/2-inch tack weld. Repeat these welds every four to six inches until you have tacked along the entire joint seam.

7

Grind the tack joints smooth. If the tack joint is done properly, the parent pieces of metal and the joint metal should be indistinguishable from each other.

Seam Welded Joints

8

Load the appropriate gauge wire for a standard MIG weld for the thickness of your panel sheet. Refer to a MIG wire chart to determine the recommended wire type, voltage and wire speed for the weld.

9

Place your MIG torch at a 20-degree angle from vertical about 1/8- to 1/4-inch from the surface of the weld joint and start an arc weld by squeezing the MIG gun trigger.

10

Weld the panel together by slowly moving the torch along the seam in a circular pattern until you reach the end of the joint.

11

Grind the joint down to blend the joint and make a smooth surface to paint over.