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Interpretation of the basic knowledge of laser welding (I)

Posted by： Hangao    Time：6/13/2024 4:09:00 PM

Laser welding, also known as laser beam welding (LBW), is a fusion welding process that uses a laser beam to melt and fuse materials together. This advanced welding technology offers many advantages, including high precision, high speed, and the ability to weld challenging materials.



The term 'How Lasers Work' stands for 'Light Amplification by Stimulated Emission of Radiation'. In laser welding, the laser acts as a concentrated heat source, providing the energy required to melt the material at the joint. The laser beam is generated in a laser resonator and then directed to the workpieces using a series of mirrors or optical fibers.

Weld Formation and Heat Flow
The laser beam is focused onto the workpieces, forming a small spot with high energy density. As the laser beam interacts with the material, it heats the surface, causing it to melt and form a molten pool. The molten pool consists of molten material from both workpieces that mix and fuse together. As the laser beam moves along the joint, the molten material solidifies, forming a strong, permanent bond. Heat flow during laser welding plays a vital role in the quality of the weld. Heat is conducted from the molten pool to the surrounding material, creating a temperature gradient. The temperature decreases with increasing distance from the molten pool. The heat affected zone (HAZ) is the area adjacent to the weld pool that undergoes thermal cycling but does not melt. The properties of the material in the heat-affected zone may change due to thermal cycling, which can affect the overall performance of the weld joint.



Types of Laser Welding
Laser welding is mainly divided into four categories based on the mode of operation: conduction mode, keyhole welding, laser brazing, and impact welding.

Conduction mode welding: In conduction mode welding, the laser beam is absorbed by the surface of the material and the heat is conducted through the material to form the weld. The weld is shallow in depth and wide in width. This mode is suitable for thin-walled parts and applications that require low penetration welding.

Keyhole mode welding: In keyhole mode welding, the laser beam penetrates deep into the material, forming a vapor cavity or "keyhole". The keyhole wall absorbs the laser energy, melts the material and forms a weld. The keyhole acts as a waveguide, directing the laser energy into the material, resulting in deep penetration and narrow welds.

Laser brazing: Laser brazing is a process that uses a laser as a heat source to melt the filler metal, thereby wetting the workpiece surface and forming a joint. The workpiece does not melt during this process. It is often used to join dissimilar materials and create joints with high aesthetic quality. The process requires precise control of laser power and speed to ensure proper wetting and spreading of the filler metal.

Impact welding: Impact welding is a process that uses a series of laser pulses to weld. Each pulse melts a small portion of the material, and subsequent pulses overlap the previous pulse to form a continuous weld. The process is suitable for spot welding or making small, precise welds on thin materials. It is often used in electronics and medical device manufacturing, where precision and minimal heat input are critical.

In the next article, we will explore the detailed process of the laser welding process step by step.

Guangdong Henkel Technology Co., Ltd.
Recommended reading: Laser welding production line
Hotline: 189-4243-7326

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