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(1) Power density. Power density is one of the most critical parameters in laser processing. With a high power density, the surface layer can be heated to the boiling point within a microsecond time range, resulting in a large amount of vaporization. Therefore, high power density is advantageous for material removal processes such as punching, cutting, and engraving. For lower power density, it takes several milliseconds for the surface temperature to reach the boiling point. Before the surface layer is vaporized, the bottom layer reaches the melting point, which is easy to form a good fusion weld. Therefore, in conductive laser welding, the power density is in the range of 10 ^ 4 ~ 10 ^ 6W / CM ^ 2.
(2) Laser pulse waveform. The laser pulse waveform is an important problem in laser welding, especially for thin-plate welding. When a high-intensity laser beam is irradiated to the surface of the material, 60 ~ 98% of the laser energy is reflected and lost on the metal surface, and the reflectance changes with the surface temperature. During a laser pulse, the reflectivity of the metal varies greatly.
(3) Laser pulse width. Pulse width is one of the important parameters of pulse laser welding. It is not only an important parameter different from material removal and material melting but also a key parameter that determines the cost and volume of processing equipment.
Laser Welding Machine
(4) The influence of defocus amount on welding quality. Laser Welding Machine usually requires a certain amount of defocus, because the power density in the center of the spot at the laser focus is too high, and it is easy to evaporate into holes. The power density distribution is relatively uniform across the planes away from the focal point of the laser. There are two ways of defocusing: positive defocus and negative defocus. The focal plane is above the workpiece for positive defocus, otherwise it is negative. According to geometrical optics theory, when the positive and negative defocus planes are equal to the welding plane, the power density on the corresponding planes is approximately the same, but the shape of the molten pool obtained is actually different. With negative defocus, greater penetration can be obtained, which is related to the formation of the molten pool. Experiments show that laser heating of 50 ~ 200us material begins to melt, forming liquid metal and partial vaporization, forming high-pressure steam, and ejecting at extremely high speed, emitting dazzling white light. At the same time, the high-concentration vapor moves the liquid metal to the edge of the molten pool, forming a depression in the center of the molten pool. When negative defocusing, the internal power density of the material is higher than the surface, and it is easy to form stronger melting and vaporization, so that the light energy is transmitted deeper into the material. Therefore, in practical applications, when large penetration depth is required, negative defocus is used; when welding thin materials, positive defocus should be used.
(5) Welding speed. The speed of the welding speed will affect the heat input per unit time. If the welding speed is too slow, the heat input will be too large, which will cause the workpiece to burn through. If the welding speed is too fast, the heat input will be too small, which will cause the workpiece to be opaque. Our company also has Metal CNC Fiber Laser Cutting Machine on sale, welcome to consult.