Laser Welding’s Practical Applications and Main Features

Laser welding is defined as a precise and efficient processing pattern regarding high-density laser beam as heat source. It is an indispensable part of laser technology application. Now, the application fields of laser welding are increasingly expanding, mainly including manufacturing, powder metallurgy, automotive industry, electronics industry, biomedicine and other related fields aimed at BT20 titanium alloy, HE130 alloy and Li-ion battery.

The features of laser welding are that the welded workpiece has extremely small deformation, with no connection gap and high welding depth/width ratio, so its welding quality is superior to that of other traditional welding patterns. But, how to keep laser welding quality stable and how to monitor laser welding process and take control of its quality are of great importance to the practical application. To be specific, laser welding usually uses inductive, capacitive, sonic and photoelectric sensors, and electronic computers to conduct weld seam tracking, defect detection and weld seam quality monitoring according to welding objects and requirements, after that, control the specific feedback and change welding parameters to make laser welding automatic. As for laser welding, focal position of laser beam is one of the most critical parameters. Under certain laser power and welding speed, the max penetration depth and best weld seams can only be obtained while the focus is within the optimal position range. To avoid and reduce factors affecting the stability of the focal position, professional clamping tools and clamping technology are required, which are complementary to the actual quality of laser welding.

Compared with other traditional welding crafts, laser welding is good at:

1.Fast speed, large depth and small deformation.

2.Welding can be performed at room temperature or under special conditions, and welding devices are simply-designed. At work, laser beam will not shift while passing through electromagnetic field; laser welding can adapt to vacuum, air and other environments containing certain gas; laser can penetrate through glass or other materials transparent relative to laser beam.

3.Refractory materials, incl. titanium and quartz, and heterogeneous stuff can also be welded at high quality.

4.After laser focusing, power density is high. When welding at high power, the depth-to-width ratio can reach 5:1, or 10:1 at most.

5. Micro welding is available. After focusing, laser beam can obtain a very small spot and be positioned, which is usually applied to the assembly welding of micro and small workpieces in mass automated production.

6. It can weld intangible parts and carry out non-contact and long-distance welding flexibly. In recent years, as optical fiber transmission has been adopted in YAG laser processing, laser welding becomes more widely promoted and applied.

7. Considering that laser beam can be separated by time and space, multi-beam and multi-station welding may come true to lay solid foundations for high-precision welding.

Nevertheless, laser welding also has certain shortcomings:

1. It requires high on assembly accuracy of welded parts, and must ensure that laser beam has no obvious deviation on workpiece. The reason is that spot size is small and weld seam is narrow after laser focusing. If workpiece assembly accuracy or beam positioning accuracy is below related requirements, welding defects will probably occur.

2. Laser generator and related systems are high-cost, requiring relatively large one-off investment at the early stage.

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