Plug welding thin metal to thick plate.

[schnappi]

As part of a sill replacement I need to plug weld the thin outer sill to a thick bit of plate near a jacking point. Do I need deep penetration into the thick plate (which is at the back) or can I just use the same settings as I'd use normally use when plug welding to the inner sill? If I'm using maximum power to penetrate the thick plate am I likely to burn up the thin outer sill? Help!

 

[Chickenjohn]

If you can get some scrap of the same gauge and experiment. Other than that, use settings somewhere between thick and thin plates, and use clamps to clamps the top sheet VERY TIGHTLY to the bottom sheet. It is often the slight gap between the sheets that causes the top one to burn away instead of plug weld to the lower.

Also use Zinc spray between the sheets to prevent rust and clean off any zinc where you will be welding.

 

[schnappi]

Thanks for the advice mate, appreciate it!

 

[calbro]

whats a plug weld?

 

[Paul.]

whats a plug weld?

A method of reproducing spot welds using a mig welder, see the tutorial here http://www.mig-welding.co.uk/plug-weld.htm

 

[calbro]

cheers paul that answer my question!

 

[panelman]

Hi, could I add that when you have lined up the panels, you should drill the plug holes part way into the thicker lower section. This starts the penetration process and allows for a lower heat setting on your welder.

 

[schnappi]

Hi, could I add that when you have lined up the panels, you should drill the plug holes part way into the thicker lower section. This starts the penetration process and allows for a lower heat setting on your welder.

Thanks for the tip, I'll do that as I've only got 90 amps to play with and this is some thick plate (just over 3mm IIRC!).