What are the differences between traditional welding methods such as laser welding, electron beam welding, ultrasonic welding and arc welding?

4. Plasma arc welding Plasma arc welding is also a kind of non-melting electrode arc welding. It uses the compressed arc (called transfer arc) between the electrode and the workpiece to realize welding. The electrode used is usually a tungsten electrode. The plasma gas used to generate the plasma arc can be argon, nitrogen, helium or their mixture. At the same time, through the nozzle with inert gas protection. When welding, filler metal can be added or not. In plasma arc welding, the arc is straight, the energy density is high and the arc penetration ability is strong. The keyhole effect produced in plasma arc welding can be used for the butt joint of most metals in a certain thickness range, and can ensure the penetration depth and weld uniformity. Therefore, plasma arc welding has high productivity and good welding quality. However, plasma arc welding equipment (including nozzle) is more complicated and requires higher control of welding process parameters. Most metals that can be welded by gas tungsten arc welding can be welded by plasma arc welding. In contrast, plasma arc welding can be carried out more easily for the welding of extremely thin metals below1mm. 7. Electron beam welding Electron beam welding is a method of welding by using the heat energy generated when concentrated high-speed electron beams bombard the surface of the workpiece. In the process of electron beam welding, the electron beam is generated and accelerated by the electron gun. Commonly used electron beam welding are: high vacuum electron beam welding, low vacuum electron beam welding and non-vacuum electron beam welding. The first two methods are carried out in a vacuum chamber. Welding preparation time (mainly vacuumizing time) is long, and the size of workpiece is limited by the size of vacuum chamber. Compared with arc welding, the main characteristics of electron beam welding are large weld penetration, small weld width and high weld metal purity. It can be used not only for precision welding of very thin materials, but also for welding of very thick parts (up to 300 mm thick). All metals and alloys that can be welded by other welding methods can be welded by electron beam. Mainly used for welding products with high quality requirements. It can also solve the welding of dissimilar metals, oxidizable metals and refractory metals. But it is not suitable for mass production. 8. Laser welding Laser welding uses a laser beam focused by a high-power coherent monochromatic optical sub-stream as a heat source for welding. This welding method usually includes continuous power laser welding and pulsed power laser welding. The advantage of laser welding is that it does not need to be carried out in vacuum, but the disadvantage is that the penetration is not as strong as that of electron beam welding. Accurate energy control can be carried out during laser welding, so as to realize the welding of precision micro-devices. It can be applied to a variety of metals, especially to solve the welding of some difficult-to-weld metals and dissimilar metals. 16. Ultrasonic welding Ultrasonic welding is also a solid-state welding method with mechanical energy as energy source. During ultrasonic welding, the high-frequency vibration of the sonotrode can cause strong crack friction on the joint surface, which is heated to the welding temperature and forms a joint under low static pressure. Ultrasonic welding can be used for welding between most metal materials, and can realize welding between metals, between dissimilar metals and between metals and nonmetals. It is suitable for the repeated production of metal wire, foil or thin metal joint below 2 ~ 3 mm