5 Ways to Solve the Defects of Laser Welding

Laser welding is one of the important aspects of the application of laser material processing technology. Is mainly used for welding thin wall material and low speed in the 1970 s, the welding process is thermal conduction, i.e. the laser radiation heating surface, the surface heat to the internal diffusion through heat conduction, by controlling the width of laser pulse, energy, peak power and repeating frequency, parameters such as melting of components, to form specific molten pool.With the advantages of high efficiency, high precision, good effect, easy automation and integration, steel laser welding machine is widely used in various industries, and plays a pivotal role in industrial production and manufacturing, including military, medical, aerospace, 3C auto parts, mechanical sheet metal Metal, new energy, bathroom hardware and other industries.

However, any processing method without a good grasp of its principle and technology, will produce certain defects or defective products, laser welding is no exception. Only a good understanding of these defects, and learn how to avoid these defects, in order to better play the value of laser welding, processing a beautiful appearance, good quality products. The following is the solution to the defect of fiber laser welding.

1.Crack

Laser continuous welding cracks are mainly thermal cracks, such as crystallization cracks, liquefaction cracks, etc., the main reason is that the welding seam in the complete solidification before the larger shrinkage force caused by, filling wire, preheating and other measures can reduce or eliminate cracks.

2.Stoma

Bore hole is an easy defect in laser welding. The laser welding pool is deep and narrow, and the cooling rate is fast. The gas produced in the liquid pool does not have enough time to escape, which easily leads to the formation of pores. However, laser welding cools quickly and the pores produced are generally smaller than those of traditional fusion welding. Cleaning the surface of the workpiece before welding can reduce the tendency of porosity, and the direction of air blowing can also affect the formation of porosity.

3.Splash

The spatter produced by laser welding will seriously affect the surface quality of the weld and contaminate and damage the lens. The spatter is directly related to the power density, and the spatter can be reduced by appropriately reducing the welding energy. If the depth is insufficient, the welding speed can be reduced.

4.Undercut

If the welding speed is too fast, the liquid metal at the back of the small hole pointing to the center of the weld will not have time to redistribute, and it will solidify on both sides of the weld to form an undercut. If the joint assembly gap is too large, the molten metal in the joint is reduced, and the undercut is also prone to occur. At the end of laser welding, if the energy drop time is too fast, the small holes are easy to collapse, resulting in local undercuts. Controlling the power and speed to match can solve the undercuts.

5.Sag

If the welding speed is slow, the weld pool is large and wide, the amount of molten metal is increased, and the surface tension is difficult to maintain the heavier liquid metal, the weld center will sink, forming collapse and pit. At this time, it is necessary to appropriately reduce the energy density to avoid the collapse of the weld pool.

Correct understanding of the defects in the laser welding process, understand the causes of different defects, can be more targeted to solve the welding seam abnormality problem of laser welding.