Laser welding is widely used in various industries due to its advantages of high efficiency, high precision, good results and ease of automation integration. It plays an important role in industrial production and manufacturing, including industries such as military, medical, aerospace, 3C automotive parts, mechanical sheet metal, new energy and bathroom hardware.
However, any processing method, including laser welding, can produce defects or subpar products if the principle and process are not properly understood.
To maximize the value of laser welding and produce high-quality products that look flawless, it is important to understand these defects and learn how to avoid them.
Through years of experience, engineers have compiled solutions to common welding defects for industry peers to reference.
1. Crack
The cracks that occur during continuous laser welding are mainly thermal cracks, such as crystallization cracks and liquefaction cracks.
The main cause of these cracks is the large retraction force generated by the weld before it is fully solidified.
Using wire filler, preheating, or other methods can reduce or eliminate these cracks.
crack welding
2. Air hole
Porosity is a common defect in laser welding.
The deep, narrow molten pool in laser welding cools quickly, making it difficult for any gas generated in the molten pool to escape, leading to the formation of pores.
However, despite rapid cooling, porosity in laser welding is generally smaller than that found in traditional fusion welding.
Cleaning the surface of the part before welding can reduce the occurrence of pores, and the direction of blowing can also impact pore formation.
Weld porosity (left)
Weld formation process (right)
3. Splash
Spatter produced during laser welding can significantly impact the quality of the weld surface and cause contamination and damage to the lenses.
Spatter is directly linked to power density, so reducing welding power can help reduce spatter.
If penetration is inadequate, reducing welding speed may also help.
Welding spatter
4. Undercut
If the welding speed is too fast, the liquid metal at the back of the small hole pointing toward the center of the weld will not have time to redistribute, resulting in solidification and shear on both sides of the weld.
A large gap in the joint assembly can also reduce the amount of caulked molten metal, making undercuts more likely to occur.
If the power decreases too quickly at the end of laser welding, the small hole may collapse, leading to local undercutting.
The proper combination of power and speed can effectively prevent the formation of undercuts.
5. Collect
If the welding speed is slow, the molten pool will be larger and wider, increasing the amount of molten metal. This can make it difficult to maintain surface tension.
When molten metal becomes too heavy, the center of the weld can sink and form collapses and holes.
In this case, it is necessary to reduce the energy density appropriately to prevent the molten pool from collapsing.
Aluminum alloy weld collapse
Having a correct understanding of the defects that can occur during laser welding and the causes of different defects allows for a more targeted approach to resolving any abnormal welding issues.
