Handheld laser welding machine is a new type of welding method, mainly for the welding of thin-walled materials and precision parts, which can realize spot welding, butt welding, stitch welding, sealing welding, etc. Small size, small deformation, fast welding speed, smooth and beautiful welding seam, no need or simple treatment after welding, high welding seam quality, no porosity, accurate control, small focusing spot, and high positioning accuracy.
Why do hand-held laser welding machines need shielding gas?
The reasons can be divided into three points.
Reason 1: The focusing lens can be protected from metal vapor contamination and liquid droplet sputtering.
The shielding gas can protect the focusing lens of the laser welding machine from metal vapor contamination and sputtering of liquid droplets. Especially in high power welding, as its jet becomes very powerful, it is more necessary to protect the lens.
Reason 2: The shielding gas effectively shields and disperses the plasma generated by high-power laser welding.
The metal vapor absorbs the laser beam and is ionized into a plasma cloud, and the shielding gas surrounding the metal vapor is also ionized by heating. If there is too much plasma, the laser beam is consumed by the plasma to some extent. Plasma exists as a second energy on the working surface, making the penetration shallower and the weld pool surface wider. By increasing the collisions of electrons with ions and neutral atoms, the recombination rate of electrons can be increased, thereby reducing the electron density in the plasma. The lighter the neutral atom, the higher the collision frequency and the higher the recombination rate; on the other hand, only the high ionization energy protects the gas, and the electron density will not increase due to the ionization of the gas itself.
Reason 3: The shielding gas can protect the workpiece from oxidation during the welding process.
The laser welding machine must be shielded with a gas, and the program should be set to shield the gas before the laser to prevent oxidation of the pulsed laser during continuous processing. Inert gases can protect the weld pool and are not a concern when certain materials do not care about surface oxidation, but helium, argon, nitrogen, and other gases are often used to protect most applications to avoid oxidation of the workpiece during welding.
This is why laser welding machines use shielding gas when welding. Remind everyone that helium is generally used as a protective gas, which can suppress the plasma to the greatest extent, thereby increasing the penetration depth and improving the welding speed; and it is light in weight, easy to escape, and not easy to cause pores. Of course, from our actual welding effect, the argon protection effect is also good.
