A - Nozzle
B - Contact tip
C - Nozzle to work distance
D - Workpiece
E - Electrode extension
F - Arc
G - Contact tip to work distance
•
If stickout is too long, the wire overheats with the current flowing through it on the way to
the weld.
•
If stickout is too short, the wire will not get hot enough to make a properly fused bead.
8.5.
Shielding gas
Shielding gas prevents atmospheric oxygen and nitrogen from getting into the weld pool and
contaminating the weld.
Various shielding gases may also:
•
Promote high welding speeds without burn-through
•
Reduce spatter and improve weld appearance
Reduce heat affected-zone
•
•
Improve wetting of base metal
In selecting a shielding gas, consider cost, weld appearance, and weld penetration. In some
cases, mixes of different gases are best for the job.
Solid Carbon-Steel
ER70S-6
Flux-Cored/Carbon-
Steel E71TGX
•
Must be used with 100% CO2 or 25% CO2 +75% Argon.
•
100% CO2 gas is economical and deeper penetration.
75% Argon + 25% CO2 has less spatter and better bead appearance.
•
•
Indoor use with no wind.
•
For auto body, manufacturing, fabrication.
Welds thinner materials (1 mm) than flux cored wires.
•
No shielding gas required.
•
EN