Resistance Welding
It is used to weld thin metal parts. The workpiece is clamped between two electrodes, and a large current is applied to melt the surfaces where the electrodes contact, thus welding is achieved through the workpiece's resistance heating. The workpiece is prone to deformation. Resistance welding joins from both sides, while laser welding only joins from one side. The electrodes used in resistance welding require frequent maintenance to remove oxides and metal adhering to the workpiece. Laser welding of thin metal lap joints does not involve contact with the workpiece, and the laser beam can penetrate areas difficult to reach with conventional welding. Welding speed is also fast.
Argon Arc Welding
Uses non-consumable electrodes and shielding gas, often used to weld thin workpieces, but the welding speed is slower, and the heat input is much greater than laser welding, making deformation more likely.
Plasma Arc Welding
Similar to argon arc welding, but its torch generates a compressed arc to increase arc temperature and energy density. It is faster and has a greater penetration depth than argon arc welding, but less so than laser welding.
Electron beam welding
It relies on a beam of accelerated, high-energy-density electrons to strike the workpiece, generating enormous heat within a small, dense area on the workpiece surface, creating a "keyhole" effect, thus achieving deep penetration welding. The main disadvantages of electron beam welding are the need for a high-vacuum environment to prevent electron scattering, complex equipment, limitations on workpiece size and shape due to the vacuum chamber, and strict requirements for workpiece assembly quality. While non-vacuum electron beam welding can be performed, poor focusing due to electron scattering affects the results. Electron beam welding also presents issues of magnetic deflection and X-rays. Because electrons are charged, they are affected by magnetic field deflection, thus requiring pre-demagnetization of the workpiece. X-rays are particularly strong under high pressure, necessitating operator protection. Laser welding, on the other hand, does not require a vacuum chamber or pre-demagnetization of the workpiece. It can be performed in the atmosphere and does not have X-ray protection issues, allowing for online operation within a production line and the welding of magnetic materials.