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The Principle of Laser Welding
The laser welding machine uses high-energy laser pulses to locally heat the material in tiny areas. The energy from the laser radiation spreads to the interior of the material through heat conduction, melting the material and forming a specific molten pool. It is a new type of welding method, laser welding mainly for thin-walled materials, precision parts welding, can achieve spot welding, butt welding, stick welding, sealing welding, etc., high depth to width ratio, small weld width, small heat-affected zone, small deformation, fast welding speed, weld seam flat, beautiful, no treatment after welding or only need simple treatment, high-quality weld seam, no porosity, can be precisely controlled, small focus light point, high positioning accuracy, easy to Automation.
It is a fusion welding process in which a laser beam is used as the energy source to impact the weld joint.
The laser beam can be guided by a flat optical element (e.g. a mirror) and subsequently projected onto the weld with a reflective focusing element or lens.
Laser welding machines are non-contact welding machines that do not require pressure during operation, but require the use of inert gas to prevent oxidation of the molten pool; filler metals are occasionally used.
Laser welding can be combined with MIG welding to form a laser MIG composite weld to achieve a large depth of fusion while the heat input is significantly reduced compared to MIG welding.
- The heat input can be reduced to the minimum required, the heat-affected zone has a small range of metallurgical changes and the deformation caused by heat transfer is also minimal.
- Welding process parameters for single-pass welding of 32 mm plate thicknesses have been checked and approved, which reduces the time required for welding of thick plates and even eliminates the use of filler metal.
- No electrodes are required, so there is no concern about contamination or damage to the electrodes. As it is not a contact welding process, the wear and tear and deformation of the machine can be reduced to a minimum.
- The laser beam can be easily focused, aligned, and guided by optical instruments, and can be placed at an appropriate distance from the workpiece and redirected between machines or obstacles around the workpiece, whereas other welding methods cannot be used due to the above-mentioned space constraints.
- The workpiece can be placed in an enclosed space (under vacuum or with a controlled internal gas environment).
- The laser beam can be focused on a small area, allowing small, closely spaced parts to be welded.
- A wide range of materials can be welded and a variety of heterogeneous materials can be joined to each other.
- High-speed welding is easily automated and can be digitally or computer-controlled.
- When welding thin materials or fine diameter wire, there is no risk of reflow as in arc welding.
- It is not affected by magnetic fields (as is the case with arc welding and electron beam welding) and can be precisely aligned with the welded part.
- Can weld two metals with different physical properties (e.g. different resistances).
- No vacuum or x-ray protection is required.
- With perforated welding, the depth to width ratio of the welding channel can be up to 10:1.
- The laser beam can be delivered to multiple workstations by switching devices.
- The position of the weld piece must be very precise and within the focus of the laser beam.
- If a fixture is used for the weld, it must be ensured that the final position of the weld is aligned with the point where the laser beam will impact.
- The maximum weldable thickness is limited by the penetration of parts much thicker than 19 mm, the production line is not suitable for the use of laser welding machines.
- Highly reflective and highly thermally conductive materials such as aluminum, copper, and their alloys can have their weldability altered by the laser.
- When welding with medium to high energy laser beams, a plasma controller is required to drive away from the ionized gas around the molten pool to ensure the re-emergence of the welding channel.
- The energy conversion efficiency is too low, usually below 10%.
- Rapid solidification of the welding channel, with possible concerns of porosity and embrittlement.
- Expensive equipment.
What Types of Laser Welding Machines Are Available, What Are Their Features And Cost-Effectiveness
1. Handheld Laser Welding Machine
A good quality laser beam, fast welding speed, firm and beautiful welds, providing users with welding solutions. High safety, welding head only useful when in contact with metal, touch switch with body temperature sensing function.
Hand-held water-cooled torch, ergonomically designed, easy to move, longer welding intervals, can finish any part of the workpiece. High electro-optical conversion efficiency, low energy consumption, easy to learn operation, no need for professional welding masters, ordinary workers can be inducted after a short rehearsal. A long-term application can greatly save processing costs.
The handheld laser welding machine has the advantages of low heat impact, not easy to deform, blackening, no traces, large welding depth, full melting, firm and reliability, etc. The handheld laser welding machine can finish welding from any angle and can weld various kinds of workpieces with messy welds and large workpieces with irregular shapes. End welding from any viewpoint.
Handheld laser welders require the user to be handheld. Long time operation will lead to fatigue, is not conducive to the welding of large original parts, the scale of application is severely restricted.
2. Desktop Laser Welding Machine
Using a benchtop laser welding machine reduces worker workload and fatigue; suitable for large objects or thick plates, with high welding quality when appropriate.
Benchtop laser welding machine occupies a large space, so it is not as flexible as a handheld.