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How to solve several common laser welding machine defects?

Apr 25,2023 | TOPTEK

With its advantages of high efficiency, high precision, good effect, good compatibility, and easy automation integration, laser welding has been widely used in various industries, and plays a pivotal role in new energy, mechanical sheet metal, 3C and other industrial manufacturing. Auto parts, military, medical, aerospace, bathroom hardware and other industries.

However, if any processing method does not master its principles and processes, it will produce certain defects or defective products, and laser welding is no exception. Only by understanding these pitfalls and learning how to avoid them can laser welding be used to its full value and produce products that look good and are of high quality. TOPTEK application engineers have summed up some solutions to common welding defects through long-term experience accumulation, for the reference of colleagues in the industry!

1. Crack
The cracks produced by continuous laser welding are mainly thermal cracks, such as crystallization cracks, liquefaction cracks, etc., which are mainly caused by the shrinkage force of the weld before it is completely solidified. Measures such as wire filling and preheating can reduce or eliminate cracks.
2. Stomata
Pores are relatively easy defects 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 has no time to escape, and it is easy to form pores. However, laser welding cools quickly, and the pores produced are generally smaller than traditional fusion welding. Cleaning the surface of the workpiece before welding can reduce the tendency of air holes, and the direction of blowing air will also affect the generation of air holes.

3. Splash
The spatter produced by laser welding seriously affects the surface quality of the weld seam, and can also pollute and damage the lens. Spatter is directly related to power density, and appropriately reducing welding energy can reduce spatter. If the penetration is insufficient, the welding speed can be reduced.

4. Undercut
If the welding speed is too fast, the liquid metal behind the small hole pointing to the center of the weld has no time to redistribute, and it solidifies on both sides of the weld to form an undercut. If the assembly gap of the joint is too large, the molten metal in the caulking will be reduced, and undercutting will easily occur. At the end of laser welding, the energy drop time is too fast, and the small hole is easy to collapse, resulting in local undercut. The matching of control efficiency and speed can solve the undercut problem well.

5. Crash

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, it is necessary to reduce the energy density appropriately to avoid the collapse of the molten pool.

Only by correctly understanding the defects generated in the welding process and understanding the causes of different defects can we solve the problem of abnormal laser weld seam in a more targeted manner.

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