Laser welding is an efficient and precise welding method that uses a high-energy-density laser beam as a heat source. Laser welding machine is one of the important aspects of the application of laser material processing technology and is widely used in the fields of automobiles, aerospace, electronics, and medical treatment. It has the advantages of fast speed, high quality, high flexibility, and green environmental protection. So, what are the advantages of laser welding compared to traditional welding methods? What difficulties will be encountered in laser welding, and how to solve these difficulties? What application fields are laser welding commonly used in? This blog will introduce it from the following three aspects.
Ⅰ.Advantages of Laser Welding
Compared with traditional welding methods, laser welding machine has the following advantages:
1. Fast speed, large depth, and small deformation.
Due to its high energy density, laser welding has fast heating and cooling speeds, a small heat-affected zone, and small welding stress and deformation. Laser welding can achieve welds with a high aspect ratio, up to 10:1.
2. Non-contact processing and high flexibility.
Laser welding does not require contact with the weldment, nor does it require electrodes or filler materials. It can reduce pollution and loss. The technology can be transmitted and transformed through optical elements, and is easy to cooperate with robots to achieve automation and multi-station processing. Laser welding can also be carried out at room temperature or under special conditions, and is suitable for welding inaccessible parts or refractory materials.
3. High quality and good performance.
Due to its low heat input and fast cooling rate, laser welding can reduce defects such as pores and cracks, and improve the density and strength of the weld. Laser welding can also achieve the connection of different metals or dissimilar materials, and improve the organization and performance.
4. Green and environmentally friendly, safe and pollution-free.
Laser welding does not produce harmful gases or noise, is not disturbed by electric or magnetic fields, and is harmless to the human body and the environment.
Ⅱ.Difficulties and Solutions of Laser Welding
1. Welding spatter:
Definition
Refers to the appearance of many metal particles on the surface of the material after welding is completed, which are attached to the surface of the material. This will affect the surface quality of the weld and will also contaminate and damage the lens.
Cause
The cause of spatter may be that the surface of the material is not clean, there are oil stains or pollutants, or the evaporation of the galvanized layer.
Solution
Clean the surface of the material before welding, appropriately reduce the welding energy, and reduce spatter.
2. Crack:
Definition
Refers to the thermal cracks caused by continuous laser welding, such as crystal cracks, liquefaction cracks, etc.
Cause
The main reason for the cracks is that the shrinkage force is too large before the weld is completely solidified.
Solution
The solution is to use measures such as wire filling and preheating to reduce or eliminate cracks.
3. Porosity:
Definition
Refers to the appearance of pores on the surface of the weld. The reason for the pores may be that the laser welding molten pool is deep and narrow, the cooling speed is very fast, and the gas generated in the liquid molten pool has no time to overflow; or the weld surface is not cleaned, or the zinc vapor of the galvanized sheet evaporates.
Solution
The solution is to clean the weld surface, improve the volatilization of zinc when heated, and adjust the blowing direction.
4. Undercut:
Definition
Refers to the poor combination of the weld and the parent material, the appearance of a groove, the depth is greater than 0.5mm, the total length is greater than 10% of the weld length, or greater than the length required by the acceptance standard.
Cause
The reason for the undercut may be that the welding speed is too fast, resulting in the liquid metal not being redistributed on the back of the small hole; or the joint assembly gap is too large, resulting in a reduction in the molten metal in the filling, or the energy drop time is too fast at the end of laser welding, resulting in the collapse of the small hole.
Solution
The solution is to control the matching of the processing power and speed of the laser welding machine to avoid undercutting; grind, clean and repair the undercutting found during inspection.
Final Thoughts
Laser welding is a high-precision and high-efficiency welding technology with broad application prospects. Different welding methods and application scenarios require different laser welding methods to achieve the best welding effect. Laser welding technology is still developing and innovating. In the future, more new lasers and new processes will appear to provide higher quality, higher efficiency, and lower cost welding solutions for all walks of life.
