Shielding gas is the inert or semi-inert gas that is pumped into a welding process to protect the weld area from atmospheric gases such as oxygen, nitrogen, and water vapor that could reduce the quality of the weld or make the welding more difficult.
The wrong selection of a Shielding Gas can lead to a porous, cracked, or weakened weld, as well as increase the amount of weld spatter. The better Shielding Gases, however, can improve the weld bead shape and weld bead penetration, while reducing the amount of fumes generated.
By monitoring the look and appearance of a Shielding Gas, a welding operator can select a Shielding Gas that dramatically increases the welding speed, quality, and deposition rate of a welding process.
GMAW Process Showing Shielding Gas
Traditionally, a method of monitoring Shielding Gas has been to listen to the arc to hear the crackle of the weld process. This was never an exact process, as the best way to monitor shielding gas is with visual means.
Why Monitoring Shielding Gas Is Important
Small, subtle changes in the chemistry of the Shielding Gas can make significant changes to the weld process. The chemistry affects the variations in arc and weld bead characteristics, which in turn have dramatic impact on the resulting weld.
For GMAW of carbon steel
Very different weld outcomes are generated depending on whether a mixture of Argon with CO2, Argon with O2, or a tri-mix of Argon\CO2\O2 is used as the shielding gas. For example, using a shielding gas rich in Argon with a small amount of Oxygen and CO2 (i.e., between 2% and 8%) works well in GMAW Spray and Short Circuit transfer modes, where the welding can be performed at lower voltages than if an Argon/CO2 mixture was used.
For GMAW of stainless steel
Mixtures rich in Helium (>50%) with small concentrations of Argon and CO2 establish a stable weld arc with good cleaning in GMAW Short Circuit transfer mode.
When using Argon-rich (>50%) shielding gas for GMAW Spray transfer mode, the addition of CO2 increases weld penetration, while adding helium improves wetting and flattens the bead profile.
Weld Cameras Enable Effective Monitoring
Using a Weld Camera and a remote display console to visually monitor the impact of gas mixtures, while also monitoring the wire type and wire feeding characteristics, greatly improves the ability for the operator to monitor and adjust the parameters for optimum performance.
The Weld Camera adds the ability to see the detail of the arc and monitor the impact of the shielding gases in real time, to determine the optimum welding procedure for your particular situation.
The speed, weld penetration, arc configuration and weld spatter characteristics are all visible to the operator using a Weld Camera, so that the operator—at a safe, remote distance looking at the display monitor—can determine how well the shielding gas is performing.