Weld Sheet Metal Without Burning Through

Normally the copper will not stick to the weld but it will provide enough backing to keep the molten weld from blowing through.

Weld sheet metal without burning through.

The more time the arc is in an area the hotter it becomes. When welding a long bead on sheet metal you ll put excessive heat into the panel and run the risk of the puddle falling through the panel. Andy gives helpful insights and tips to mig weld thin sheet metal. Short quick welds when welding sheet metal with a mig welder you do not want to try and run one long bead like when you re welding heavier metal.

Typical aluminum alloys for sheet fabrication are 3003 and 5052. A 5356 filler metal also works for 5052 materials specifically. The carbon acts as an excellent heat sink and the backside of the weld is fairly smooth with minimal pitting. If you have access to the back of the panel you can hold a piece of sheet copper behind the hole and it will be easier to weld it up.

For mig welding sheet metal it is often recommended to use an electrode wire of the smallest diameter to prevent burn through and warping. I use magnets to hold the copper sheet to the back side of the panel. Clamp a piece of used carbon vane from a pump blower to the back of the sheet metal. To prevent burn through and warping don t whip or weave the torch.

A better technique is to move around the weld seam doing short quick stitch welds that you eventually connect all together. Sheet metal warps easily and also can burn through easily. Set the welder controls at the proper setting and weld the piece. The main reason to use a smaller diameter wire is that it takes less heat for melting and hence the metal around the weld is not heated to a very great extent.