Study of shielding nozzles for CO₂ laser welding Available to Purchase

The principle behind CO₂ laser welding is to focus the laser beam onto the parts that need welding. The small size of the focal spot allows the energy to be concentrated so that very high power densities can be reached. These high power densities cause a high level of vaporization, which “hollows out” the welding pool, creating a deep and narrow capillary “keyhole” in the sheet metal, which is filled with a mixture of metallic vapours and plasma. When the capillary is created, the metallic vapour plasma that escapes from it, may, under certain conditions, cause the ionisation of the ambient environment and so lead to the appearance of a gaseous plasma. This plasma may absorb all or part of the incoming laser beam, and so leads to a significant decrease in penetration depths. This is why helium is usually used as shielding gas as its high ionisation potential removes any risk of this plasma appearance.