Solutions to Laser Welding Defects
As industrial manufacturing develops in the direction of high-end, intelligent, and green, driven by the demand for new energy vehicles, lithium batteries, semiconductors, and emerging markets, the demand for laser welding continues to be stimulated, and the application scope and market continue to expand. Especially in the fields of consumer electronics, new energy vehicles and other fields, the requirements for laser welding are getting higher and higher, providing a huge market space for laser welding.
However, any processing method will produce certain defects or defective products if its principles and processes are not mastered, and laser welding is no exception. Only by having a good understanding of these defects and learning how to avoid them can we better utilize the value of laser welding and process products with beautiful appearance and high quality. Through long-term experience accumulation, QUESTT welding application engineers have summarized some solutions to common welding defects for reference and communication by industry colleagues!
1.Crack
The cracks generated in continuous laser welding are mainly thermal cracks, such as crystal cracks, liquefaction cracks, etc. The main reason is that the weld produces a large shrinkage force before it is completely solidified. Measures such as wire filling and preheating can reduce the cracks. or eliminate cracks.
2. Stomata
Porosity is a defect that is easily produced in laser welding. The molten pool of laser welding is deep and narrow, and the cooling rate is very fast. The gas generated in the liquid molten pool does not have enough time to escape, which can easily lead to the formation of pores. However, laser welding cools quickly and the pores produced are generally smaller than traditional fusion welding. Cleaning the workpiece surface before welding can reduce the tendency of pores, and the direction of blowing will also affect the occurrence of pores.
3. Splash
The spatter produced by laser welding seriously affects the surface quality of the weld and can contaminate and damage the lens. Spatter is directly related to power density, and appropriately reducing welding energy can reduce spatter. If penetration is insufficient, the welding speed can be reduced.
4. Undercut
If the welding speed is too fast, the liquid metal from the back of the small hole pointing toward the center of the weld will not have time to redistribute, and will solidify on both sides of the weld to form undercuts. If the joint assembly gap is too large, the melted metal for filling the joints will be reduced, and it is easy to produce undercuts. At the end of laser welding, if the energy decrease time is too fast, the small hole will easily collapse, resulting in local undercut. Controlling the power and speed to match can effectively solve the problem of undercut.
5.Collapse
If the welding speed is slow, the molten pool is large and wide, the amount of molten metal increases, and the surface tension is difficult to maintain the heavier liquid metal, the center of the weld will sink, forming collapses and pits. At this time, the energy density needs to be appropriately reduced to avoid The molten pool collapsed.
Correctly understanding the defects produced during the laser welding process and understanding the causes of different defects can help us solve the problem of abnormal weld seams during the laser welding process in a more targeted manner.