Advantages and disadvantages of laser welding
(1) The amount of heat input can be minimized, the metallographic range of the heat affected zone is small, and the deformation caused by heat conduction is also the lowest;
(2) The welding process parameters of 32mm plate thickness single pass welding have been qualified, which can reduce the time required for thick plate welding and even eliminate the use of filler metal;
(3) There is no need to use electrodes, no concerns about electrode contamination or damage. And because it is not a contact welding process, the wear and tear of the machine can be minimized;
(4) The laser beam is easy to focus, align and guided by optical instruments, and can be placed at an appropriate distance from the workpiece and can be redirected between the implements or obstacles around the workpiece. Other welding methods are subject to the above space limitations. Can't play;
(5) The workpiece can be placed in a closed space (under vacuum or internal gas environment under control);
(6) The laser beam can be focused in a small area to weld small and closely spaced components;
(7) The range of weldable materials is large, and various heterogeneous materials can be joined to each other;
(8) It is easy to automate high-speed welding, and it can also be controlled by digital or computer;
(9) When welding thin materials or thin-diameter wires, it is not easy to have reflow due to arc welding;
(10) It is not affected by the magnetic field (easy for arc welding and electron beam welding), and can accurately align the weldment;
(11) Two metals that can be soldered with different physical properties (such as different resistances);
(12) No vacuum is required and X-ray protection is not required;
(13) If the perforation welding is used, the weld bead depth can be up to 10:1;
(14) The switching device can transmit the laser beam to a plurality of workstations.
(1) The position of the weldment must be very precise, and must be within the focus range of the laser beam;
(2) When the fixture is to be used with a fixture, it must be ensured that the final position of the weldment is aligned with the weld point that the laser beam will impact;
(3) The maximum weldable thickness is limited by the penetration of the workpiece with a thickness exceeding 19 mm, and the laser welding is not suitable on the production line;
(4) Highly reflective and highly thermally conductive materials such as aluminum, copper and their alloys, etc., the weldability will be changed by the laser;
(5) When performing medium-to-high-energy laser beam welding, a plasma controller is used to drive out the ionized gas around the molten pool to ensure re-emergence of the weld bead;
(6) The energy conversion efficiency is too low, usually less than 10%;
(7) The weld bead is rapidly solidified and may have pores and embrittlement concerns;
(8) The equipment is expensive.
In order to eliminate or reduce the defects of laser welding and better apply this excellent welding method, some processes of composite welding with other heat sources and lasers are proposed, mainly including laser and arc, laser and plasma arc, laser and induction heat source. Welding, dual laser beam welding, and multi-beam laser welding. In addition, various auxiliary technological measures such as laser filler welding (which can be subdivided into cold wire welding and hot wire welding), external magnetic field assisted laser welding, protective gas controlled molten pool deep laser welding, and laser assisted friction stir welding, etc are also proposed.