Laser welding is characterized by its high strength, minimal thermal deformation, effective sealing, consistent weld size and nature, and ability to weld materials with high melting points (such as ceramics) and those that are prone to oxidation.
Laser welding is particularly useful for pacemakers, which are effectively sealed and have a long service life, as well as being small in size.
Laser heat treatment
With laser irradiation of the material, the appropriate wavelength, irradiation time control and power density can be selected to make the surface of the material melt and recrystallize, achieving the purpose of quenching or annealing.
Laser heat treatment has the advantage of being able to precisely control the depth of heat treatment and select the specific area to be treated.
The deformation of the part is minimal and it can effectively handle complex and intricate shapes, as well as process blind and deep holes in internal walls.
For example, laser heat treatment can extend the life of a cylinder piston and restore damage caused by ion bombardment to silicon materials.
Strengthen treatment
Laser surface strengthening technology uses a high-energy density laser beam to quickly heat and cool the workpiece.
In metal surface laser strengthening, when the energy density of the laser beam is low, it can be used for metal surface transformation. At high beam density, the part surface acts similar to a moving crucible, enabling a variety of metallurgical processes such as surface remelting, surface carbonation, surface alloying and surface coating.
These functions have the potential to bring significant economic benefits to the manufacturing industry through material replacement technology.
In the modification of tool materials, melt treatment is the main application. It involves melting the surface of the metallic material under laser beam irradiation and then rapidly solidifying to form a new surface layer.
Material surface changes can be categorized into several types, including alloying, dissolving, remelting refinement, glazing and surface composite.
Laser melting involves using laser parameters to rapidly melt and condense the surface of the material, resulting in a more refined and homogeneous organization with improved surface properties. This is a surface modification technology.
The advantages of laser surface fusion include:
- Surface fusion typically does not add any metallic elements and forms a metallurgical bond with the molten layer and matrix material.
- During the laser melting process, impurities and gases can be eliminated, leading to high hardness, abrasion resistance and corrosion resistance in the magazines obtained by quenching and recrystallization.
- The fusion layer is thin, with a small thermal effect area, and the surface roughness and part size have minimal impact. In some cases, no additional polishing is required and the part can be used directly.
- The solubility limit of solute atoms in the matrix, grain and ultrafine particles is improved, allowing the formation of a metastable phase and diffusionless or even amorphous single-crystalline structure, leading to excellent performance in the new alloy that cannot be achieved through traditional methods. .
The beam can be directed through an optical path, allowing the processing of parts with special positions and complex shapes.
Combining the benefits of technology with the limitations of widely used techniques, the application of laser technology for surface strengthening of tool materials increases wear resistance and tool life, especially for ceramic and carbide cutting tools with high hardness and heat resistance.
This improves processing efficiency and accuracy and allows materials such as hardened steel to be processed under challenging conditions.
Despite their high hardness and heat resistance, ceramic and carbide cutting tools have limited application due to their relatively low strength and low toughness. The application of laser surface hardening technology to these materials is therefore a subject of significant research and has a wide range of potential applications.
Microfabrication
By selecting the appropriate laser wavelength and utilizing various optimization techniques and approaching the diffraction limit of the focusing system, a stable, high-quality light beam with a micro-sized focal spot can be obtained.
Its sharp and precise “light knife” characteristics are used to engrave high-density micromarks and directly write high-density information.
It can also leverage its optical trap “force” effect to manipulate small transparent objects, such as through high-precision grid engraving.
With the help of CAD/CAM software to simulate and control patterns or text, high-fidelity marking can be achieved.
Furthermore, its optical trapping “binding force” can be used for manipulating biological cells, known as biological light tweezers.
Microfabrication Process
The fine machining process
Most fine cuts on the convex (outer) surface are made using single crystal diamond tools or cutters. The tip radius is approximately 100 μm and the diamond wheel has a 45° conical cutting surface when rotated.
The minimum machinable size of the concave (inner) surface is limited by the tool size. For example, a twist drill can be used to machine a 50μm hole, but for smaller holes, a flat drill must be used as twist drill products are not available.
A fundamental challenge in microfabrication is ensuring that the tool's installation posture and its coaxial alignment with the spindle axis are consistent with the coordinate system. Otherwise, it may be difficult to get a small cut. To solve this problem, the same machine tool can be used for both tool production and microprocessing, thus avoiding clamping errors caused by the use of different working conditions.
A wire discharge grinder can be used on the machine tool to produce a 50 μm wide groove.
Fine electrical processing technology
The machining of microshafts and profiled bars can be carried out using wire discharge grinding (WEDG). Its unique discharge circuit allows only 1/100th of common EDM. To obtain a smoother surface, WECG can be used after WEDG processing, which removes a thin surface layer using deionized water at low current.
Micro-EDM machines, such as the MG-ED71 from Japan's Matsushita Electric Industrial Co., Ltd., can be used for this process. These machines have a positioning control resolution of 0.1 μm and a smaller processing aperture of 5 μm, resulting in a surface roughness of 0.1 μm.
For example, a 9-tooth stainless steel gear with a diameter of 300 μm and a thickness of 100 μm can be machined. The rough contour is first drilled with a φ24 μm electrode, and the contour is then scanned with a φ31 mm electrode according to the tooth profile, resulting in an accuracy of ±3 μm.
This technology can also be used to process a miniature stepped shaft with a minimum diameter of 30 μm and a processed keyway section of 10 μm x 10 μm. Electrodes for machining small parts must be made on the same machine tool, otherwise it may be difficult to process holes smaller than 100 μm in diameter due to electrode connection and assembly errors.
For example, electrodes from micro-EDM machine tools or ultrasonic processing tools can be used to process micro-holes of 5 to 10 μm. Compared to micromachining and fine machining, material removal rates are low, but the processing size can be smaller and the hole diameter ratio can be as high as 5 to 10. This makes it particularly superior for cavities thin and complex concave. processing.
III. Laser processing development
- High power, high efficiency, high precision
With the development of the laser industry and the changing demands of the downstream industry, medium and high-power laser equipment have become a market focus. In particular, the emergence of fiber laser cutting machines of 20 kW or even higher power has driven the maturation of laser technology, constantly pushing the limits of cutting thickness.
As we look to the future, with the upgrade of laser cutting equipment, high-power and high-speed laser cutting machines will replace traditional machining equipment due to their excellent efficiency and precision advantages, greatly improving efficiency and quality of industrial processing.
- Digitization, Intelligentization
In the era of digital economy, the advancement of digital technology has greatly improved the efficiency of production and innovation. Effective integration of laser technology with numerical control technology will give laser cutting equipment the ability to analyze, judge, infer and make decisions about the cutting process, thereby realizing automation and intelligence of all parts of the cutting equipment. manufacturing.
At the same time, rising labor costs in the laser industry and the upgrading and iteration of industrial technology also drive the need for laser cutting equipment to evolve to higher levels of automation and intelligence.
As we can predict, with the rapid advancement of smart manufacturing strategies, digitalization and intelligence in the field of laser cutting will become an inevitable trend. Highly intelligent multifunctional laser cutting equipment will continue to emerge, significantly increasing industrial processing efficiency and achieving efficient production management.
- Flexibility, Integration
In the era of intelligent manufacturing, downstream user processing scenarios are becoming more diverse and complex, increasing the demand for customized laser processing equipment. This requires laser cutting companies to be more flexible in their product applications to meet different processing scenarios and meet diverse customer needs.
Therefore, the use of modular design to improve equipment integration, adaptability and functionality, and to achieve consumer-oriented flexible production, will become an important development direction for the future laser cutting equipment industry.
