Laser-based processing or forming through the interaction between laser and material, performed according to specific requirements, is collectively called photomanufacturing. Over the past 20 years, photomanufacturing technology has penetrated high-tech fields and industries, beginning to replace or transform certain traditional manufacturing sectors. In the automotive industry of developed countries, 50%-70% of parts are produced using laser processing. Photomanufacturing technology is playing an increasingly important role in enhancing automotive R&D and manufacturing levels.
1. Characteristics of photomanufacturing technology
Currently, lasers are the primary light source used in photomanufacturing technology. Laser beams have high energy density, high coherence, and high directivity, giving photomanufacturing many advantages over traditional manufacturing techniques. The tool used in this technology is the "laser knife," which has no tool wear during processing; there is no cutting force impacting the workpiece during processing, thus no cold deformation of the workpiece; due to the high energy injection speed, the thermal effect on the workpiece is minimal, resulting in very small thermal deformation—approaching or achieving a "cold" processing state—enabling high-precision manufacturing that conventional technologies cannot perform. Lasers have excellent spatial control (beam direction changes, rotation, scanning, etc.) and temporal control (on/off, pulse intervals), making them particularly suitable for automated processing with high production efficiency in mass manufacturing. Laser processing accommodates great freedom in material type, shape, size, and processing environment; it produces low noise, no harmful radiation or residues, and causes minimal environmental pollution during production; it saves molds, shortens product development cycles, and lowers development costs; it minimizes material waste and reduces manufacturing costs in large-scale production.
2. Categories of photomanufacturing technology in the automotive industry
Photomanufacturing technology in the automotive industry can be divided into three categories: photonic "cold" processing, photonic "thermal" processing, and photonic rapid prototyping.
1. Photonic "cold" processing technology
Photomanufacturing technologies corresponding to conventional cold processing include laser cutting, laser drilling, laser marking, and laser trimming.
Laser cutting is fast, produces smooth and flat cuts with good edge parallelism, requires no secondary processing after cutting; the cut width is narrow; cuts are free of mechanical stress and shear burrs; machining accuracy is high with good repeatability, and the workpiece surface remains undamaged.
Laser drilling is fast and efficient, suitable for high-volume, high-density hole processing; it achieves high depth-to-diameter ratios and can process hard, brittle, soft, and other materials, even drilling small holes on inclined surfaces of difficult-to-process materials; the process is clean and pollution-free.
Laser marking is a non-contact marking method with high speed; markings are resistant to wear, and laser marking machines easily integrate with production lines.
Laser trimming is a machining method similar to milling in mechanical processing, using a focused laser beam to cut materials layer by layer.
2. Photonic "thermal" processing technology
Photomanufacturing technologies corresponding to conventional thermal processing include laser welding, laser surface hardening, laser cladding, and alloying.
Laser welding uses a high-intensity laser beam to locally heat the metals to be joined above their melting points, fusing them into a weld joint. It can weld high melting point metals, non-metals, composites, and special materials; it can also weld dissimilar materials and special structures. Weld seams have a "self-cleaning" effect, resulting in high weld quality; precise welding can be achieved generally without filler metal. Using optical fiber delivery systems, laser beams can integrate with multiple devices to form flexible processing systems with high automation and production efficiency. A key advantage of high-energy beam welding with lasers is that it does not require a vacuum chamber and produces no X-rays.
Laser surface hardening is divided into laser phase transformation hardening and laser melting hardening. Laser phase transformation hardening, also called laser quenching, rapidly heats the metal or alloy surface with a high-energy laser beam to above the phase transition point. When the laser beam moves away, rapid cooling occurs due to heat conduction with the cold substrate, resulting in a fine hardened layer with hardness generally higher than conventional quenching hardness. Laser melting hardening is similar, but the laser heats the material surface to a higher temperature, forming a fine microstructure melting hardened layer on the surface.
Laser cladding uses a high-energy laser beam to irradiate cladding material, rapidly melting it together with a thin layer of the substrate surface, forming a metallurgically bonded alloy coating with completely different composition and properties from the substrate.
3. Photonic rapid prototyping technology
Photonic rapid prototyping is a process controlled by computer, which, based on CAD and other design models and data of parts, uses laser beams to cure forming materials layer by layer. Points and lines construct part surfaces (layers), which are precisely stacked to form three-dimensional solid models or parts. Using photonic rapid prototyping technology can significantly shorten product development cycles, greatly reduce development costs, quickly produce products that adapt to market changes, and maintain or enhance product competitiveness. It is also an effective technical path to achieve concurrent engineering and agile manufacturing.
Entering the new century, the automotive industry is moving toward lean production with flexible processing according to customer requirements. Flexible modular production has emerged, and modern automotive industry is developing toward high-tech direction. Automotive technology is undergoing a transformation from traditional mechanical manufacturing to advanced manufacturing technology. Photomanufacturing injects vitality into automotive development and production. It is expected that photomanufacturing technology will rapidly develop in the automotive industry this century, becoming an important processing method in automotive manufacturing.
