Laser welding is an efficient and precise welding method that utilizes a high-energy-density laser beam as the heat source. It offers advantages such as high efficiency, precision, and ease of use. Today, laser welding finds widespread applications across various industries including electronics, automotive manufacturing, aerospace, and more.
However, laser welding is not without its limitations. Occasionally, errors may occur during processing due to operational or parameter setting reasons. Understanding these limitations and learning how to avoid them is crucial to fully harness the value of laser welding.
Top 7 Common Defects and Solutions
Here is a detailed analysis of the top 7 common defects in laser welding and their solutions.
1.Welding Spatter
Description: After welding, numerous metal particles appear on the surface of the workpiece. These particles not only affect the appearance of the weld seam but may also contaminate or damage the lens.
Causes: Mainly due to inadequate cleaning of the processed material or workpiece surface, resulting in oil stains, contaminants, or volatilization of zinc coatings. Additionally, spatter is directly related to power density, with excessive power density exacerbating spatter.
Solution: Prior to welding, ensure the cleanliness of the material or workpiece surface by removing all oil stains and contaminants. Additionally, reducing welding energy can help minimize spatter. If penetration depth is insufficient, consider lowering the welding speed.
2.Cracks
Description: Cracks generated during continuous laser welding are primarily thermal cracks, such as crystal cracks and liquefaction cracks. These cracks significantly affect the strength and reliability of the weld seam.
Causes: Mainly due to excessive shrinkage force before complete solidification of the weld seam, as well as thermal stress generated during welding or shrinkage stress during cooling exceeding the material’s bearing capacity.
Solution: Optimize welding parameters and processes, control temperature gradients during welding, and reduce stress concentration. Furthermore, appropriate preheating and post-weld heat treatments can alleviate stress and reduce crack formation.
3.Porosity
Description: Pores appear on the surface of the weld seam, which can reduce the strength and sealing of the weld seam.
Causes: The narrow and deep weld pool in laser welding, coupled with rapid cooling, makes it difficult for gases to escape. Additionally, gas residues or impurities in the welding area can lead to pore formation.
Solution: Thoroughly clean the welding surface to ensure cleanliness. Use appropriate shielding gas and welding parameters to enhance protection of the welding area. Additionally, control temperature and speed during welding to reduce gas dissolution and outgassing.
4.Weld Undercut
Description: Poor bonding between the weld seam and base metal results in a groove or depression.
Causes: Excessive welding speed prevents liquid metal in the weld seam from redistributing promptly. Large gaps in joint assembly lead to insufficient filler metal. Rapid energy decrease at the end of laser welding causes collapse of small holes.
Solution: Control welding current and speed of the laser welding machine, appropriately adjust arc length, and apply proper weaving techniques and electrode angles. For existing welding undercut, polishing, cleaning, and repair can be performed.
5.Weld Seam Build-Up and Depression
Description: Weld seam build-up refers to excessive filler metal deposition, while weld seam depression refers to depressions on the weld seam metal surface.
Causes: Weld seam build-up typically results from excessive wire feeding speed or slow welding speed. Weld seam depression may occur due to poor centering of the welding point or deviation of the beam center from the weld seam center, causing partial base metal melting.
Solution: Adjust wire feeding speed and welding speed to ensure proper weld seam deposition. For weld seam depression, adjustment of wire feeding matching is necessary to ensure alignment of beam center and weld seam center during welding.
6.Weld Deviation
Description: Weld seam metal fails to solidify at the center of the joint structure.
Causes: Inaccurate positioning during welding or inaccurate alignment of filling welding time and wire position.
Solution: Precise positioning and fixation should be performed before welding to ensure stability of workpieces and wires during welding. Additionally, adjust the welding time and wire position to ensure solidification of the weld seam at the center of the joint structure.
7.Surface Inclusions
Description: Surface inclusions mainly occur between layers during welding.
Causes: In multi-layer and multi-pass welding, incomplete or uneven coating between layers; improper welding techniques, such as low welding input energy or excessive welding speed.
Solution: Thoroughly clean the coating between layers in multi-layer and multi-pass welding to ensure smooth and clean weld seams for each layer. Additionally, choose reasonable welding current and speed to avoid surface inclusions caused by improper welding techniques.
Examples of laser welding processing
Tips for Laser Welding
Laser welding offers the advantage of achieving both welding strength and aesthetics, making it an ideal joining method for thin sheets due to its low deformation and easy condition management. However, it also has drawbacks such as poor gap handling capability and limited suitability for build-up welding.
Improving Bending Process Accuracy
Laser welding demands high precision in workpiece assembly. Before welding, ensuring the flatness and alignment of workpiece edges can reduce gaps during welding and enhance welding quality. This can be achieved by improving the accuracy of the bending process.
Implementing Fixtures
To maintain stability during welding, fixtures can be employed to secure workpieces. This prevents movement or deformation of workpieces during welding, ensuring smooth welding processes.
Considering Design Modifications
Merely transitioning from traditional methods like TIG welding to laser welding while maintaining the original drawings may lead to processing difficulties or failure to achieve desired results. Therefore, it’s essential to consider the characteristics and requirements of laser welding during the design phase and make necessary adjustments and optimizations.
Designing With Laser Welding in Mind
To fully leverage the strength and aesthetic advantages of laser welding, it’s recommended to design products with laser welding as a prerequisite. This allows better utilization of laser welding characteristics, avoids unnecessary processing challenges, and enhances the overall quality and performance of the product.
Conclusion
In summary, in order to prevent the occurrence of these defects, close attention should be paid to the welding process, and parameters and operating methods should be adjusted in a timely manner. If you still need to know about high-quality laser welding services, BoYi has all the technical expertise you need. Their service prices are affordable and they will not compromise quality at any stage of the process.