Analysis of Optical Rapid Prototyping Technology in the Automotive Industry

The processing or forming of lasers according to certain requirements through the interaction with materials is collectively referred to as optical manufacturing. In the past 20 years, optical manufacturing technology has penetrated into the field of high-tech and industry, and has begun to replace or transform some traditional processing industries. In the automotive industry of developed countries, 50%-70% of the parts are completed by laser processing. Optical manufacturing technology is playing an increasingly important role in improving the research and development and manufacturing level of the automotive industry.

1. Characteristics of optical manufacturing technology

At present, the light source used in optical manufacturing technology is mainly laser. The laser beam has the characteristics of high energy density, high monochromaticity and high directivity, which makes optical manufacturing technology have many advantages that traditional manufacturing technology cannot match. The tool used in this technology is "laser knife", which does not wear the tool during processing; there is no cutting force on the workpiece during processing, so the workpiece does not have cold processing deformation; due to the high energy injection speed during processing, the thermal effect on the workpiece is very small, so the thermal deformation of the workpiece is very small, which can approach or reach the "cold" processing state, and realize high-precision manufacturing that conventional technology cannot perform; laser has good spatial control (direction change, rotation, scanning, etc. of the beam) and time control (on, off, pulse interval), which is particularly suitable for automated processing and has high production efficiency in large-scale manufacturing; the material, shape, size and processing environment of the laser processing object have great freedom; low noise, no harmful rays and residues, and the production process has little pollution to the environment; it can save molds, shorten product development cycle, and reduce development costs; less material waste, low manufacturing cost in large-scale production.

2. Categories of optical manufacturing technologies in the automotive industry

Optical manufacturing technology in the automotive industry can be divided into three categories: optical "cold" processing, optical "hot" processing, and optical rapid prototyping.

1. Optical "cold" processing technology

The optical manufacturing technologies corresponding to conventional cold processing processes include laser cutting, laser drilling, laser marking and laser cutting.

Laser cutting has fast speed, smooth and flat incision, good parallelism of cutting edge, no need for subsequent processing; narrow cutting slit; no mechanical stress and shear burr; high processing accuracy, good repeatability, and no damage to the workpiece surface.

Laser drilling is fast and efficient, and is suitable for processing large numbers of high-density group holes. Laser drilling can achieve a large depth-to-diameter ratio and can be used on a variety of hard, brittle, and soft materials, and can even process small holes on the inclined surfaces of difficult-to-process materials. The laser drilling process is clean and pollution-free.

Laser marking is non-contact marking with high speed and the mark is not easy to wear out. The laser marking machine can be easily combined with the assembly line.

Laser cutting is a process similar to milling in mechanical processing. It uses a focused laser beam to cut the material layer by layer.

2. Photothermal processing technology

The optical manufacturing technologies corresponding to conventional thermal processing processes include laser welding, laser surface strengthening, laser cladding and alloying.

Laser welding is a process that uses a high-intensity laser beam to locally heat the metal to be welded to a temperature above the melting point to fuse the metal together to form a welded joint. It can weld special materials such as high-melting-point metals, non-metals, composite materials, and can also weld dissimilar materials and special structures; the weld has a "self-purification" effect and high weld quality; it can perform precise welding and generally does not require filler metal; through the light guide system, the laser beam and multiple devices form a flexible processing system, with a high degree of automation and high production efficiency; in high-energy beam welding, the biggest feature of laser welding is that it does not require a vacuum chamber and does not generate x-rays.

Laser surface strengthening is divided into laser phase change hardening and laser melting hardening. Laser phase change hardening is also called laser quenching. It uses a high-energy laser beam to quickly scan the workpiece, so that the surface temperature of the irradiated metal or alloy rises to above the phase point at a very fast speed. When the laser beam leaves the irradiated part, due to the heat conduction, the cold matrix is ​​rapidly cooled and self-quenched, resulting in a finer hardened layer structure, and the hardness is generally higher than the conventional quenching hardness; the laser melting hardening process is similar to the above process, the difference is that the laser makes the material surface heat up to a higher temperature, and finally a layer of fine flame hardening layer is formed on the surface of the part.

Laser cladding is the process of using a high-energy laser beam to irradiate the cladding material, causing it to quickly melt together with a thin layer on the surface of the substrate, forming an alloy coating that is metallurgically bonded to the substrate and has completely different composition and properties.

3. Optical rapid prototyping technology

光快速成型技术原理是在计算机的控制下，根据零件的cad等设计模型及数据，用激光束将成型材料逐层固化，由点、线构造零件的面（层），由面精确堆积成三维实体模型或零件的过程。采用光快速成型技术，可显著缩短产品研制周期，大大降低研制费用，能够迅速生产出适应市场变化的产品，保持和加强产品在市场上的竞争力。同时，采用光快速成型技术也是实现并行工程及敏捷制造的有效技术途径。

Entering the new century, the automobile industry is entering a lean production stage that can perform flexible processing according to user requirements. Flexible modular production methods have emerged in the automobile industry. The modern automobile industry is also developing in the direction of high-tech technology. Automobile technology is undergoing a transformation from traditional mechanical manufacturing technology to advanced manufacturing technology. Optical manufacturing technology has injected vitality into the development and production of automobiles. It can be expected that the application of optical manufacturing technology in the automobile industry will develop rapidly in this century and will become an important processing method in the automobile industry.