Shielding for spot welding

[drivewasher]

Hi all,

Just thinking (Dangerouse I know)
Been watching "How its made" they showed an electric spot welder welding a chassis. What keeps the weld pool or molten steel from oxidizing, im Mig we use a gas to "shield" the weld or in stick flux is on the stick, or flux is in the wire for gassless mig.
So why no flux or shield on a spot welder???

 

[GeorgeB]

Hi all,

Just thinking (Dangerouse I know)
Been watching "How its made" they showed an electric spot welder welding a chassis. What keeps the weld pool or molten steel from oxidizing, im Mig we use a gas to "shield" the weld or in stick flux is on the stick, or flux is in the wire for gassless mig.
So why no flux or shield on a spot welder???

I think it's because there's no arc as such in spot welding. Instead, it's resistance welding. The metal is melted because it's the point of highest resistance in the high current circuit.

 

[Wozzaaah]

This might help explain George's answer to those who've never seen spot welding carried out.
Spot welding in slow motion

 

[Hitch]

The most molten part or the spot weld should be right in the middle, where the two parts join, and pressure is applied. The outside doesnt form a pool as such, and is protected by the fingers/electrodes off the machine anyway.