What are the effects of common process parameters of fiber laser welding machine on welding results?

Laser welding is one of the important application directions of laser machining technology. Compared with traditional welding, fiber laser welding has many advantages. High welding quality, faster efficiency. At present, it has been widely used in metal manufacturing, powder metallurgy, automobile, electronics, medicine and other industries.

There are many factors affecting the working quality of fiber laser welding machine, including power density, laser pulse, defocus, welding speed and auxiliary gas. So what is the impact of these parameters on the work of fiber laser welding machine?

  1. Laser power density
    The power density of fiber laser welder machine is one of the most important parameters.

When welding with high power density laser, the surface material can be heated to boiling in a very short time. Suitable for material removal, such as drilling, cutting, engraving, etc.

When the laser source with lower power density is used, the underlying material can be melted before the surface material is vaporized, thus forming good deep fusion welding conditions.

Therefore, in fiber laser welding, the power density is usually used 104-106W/cm²

2.Laser pulses
① Laser waveform
The waveform of the laser pulse is an important parameter to distinguish between material removal and material welding, which also determines the volume and price of the welding equipment.

② Laser pulse width
Laser pulse width is determined by fusion depth and heat affected zone. The longer the pulse width, the larger the affected area and the deeper the fusion depth. However, it is worth noting that the increase of pulse width will reduce the peak power. So increasing the pulse width is generally used in the heat conduction welding work. The weld size is wide and shallow, suitable for lap welding of thin plate and thick plate.

3.Defocus quantity
Fiber laser welding process usually requires a certain amount of defocus, because the focus position power density is too high, easy to evaporate to form holes.
Defocus can be divided into positive defocus and negative defocus. In practice, negative defocus can obtain greater melting depth.

4. Welding speed
The welding speed determines the welding surface quality, penetration depth, heat affected zone, etc. The faster the welding speed, the less heat per unit area, easy to cause welding impenetrable. Too slow speed will lead to welding penetration and the formation of holes easily.

5.Auxiliary gas
Auxiliary gas is an indispensable process in high power welding.

It can not only prevent the pollution caused by the material sputtering to the lens, but also prevent the plasma generated in the welding process from focusing too much and prevent the laser from shining on the material surface.

In fiber laser welding, inert gases such as helium, argon and nitrogen are usually used as auxiliary gases to avoid the oxidation reaction of materials in the welding process. In addition, the type of auxiliary gas, flow rate, blowing angle and other factors will also have a certain impact on the welding effect.

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