The automotive industry is continuously transforming towards low-carbon, electrification, and intelligence. Whether it is the energy efficiency upgrade of traditional power, or the development of batteries, sensors, and lightweight components for new energy vehicles, they are all related to processing accuracy, material adaptability, and finished product consistency. Put forward unprecedented stringent requirements. Femtosecond laser with ultra-short pulse as the core feature, with its unique cold ablation processing mechanism, breaks through the inherent limitations of traditional mechanical processing, EDM and long pulse laser processing, and gradually becomes an indispensable core process in the manufacture of high-end automotive parts.
The pulse width of the femtosecond laser reaches the femtosecond magnitude, the time of the pulse acting on the material is extremely short, the energy completes the deposition and the material peeling in an instant, and the heat is too late to diffuse to the surrounding substrate, forming a cold working effect that is almost free of heat-affected zone. Common defects such as recast layer, micro cracks and thermal deformation will not appear in the processing area, and the processing edge is clean and free of burrs. In many scenarios, secondary processes such as subsequent polishing, deburring and grinding can be omitted. At the same time, it belongs to non-contact processing, there is no tool wear, can be in metal, ceramics, carbon fiber composite materials, films, leather and other heterogeneous materials to achieve micron or even sub-micron level of controllable molding, natural adaptation of the automotive industry multi-material, high precision, high reliability manufacturing needs.
In the field of internal combustion engines and hybrid power components, the first scene of femtosecond laser to achieve large-scale landing is the fuel injector micro-hole processing. The nozzle hole shape of the direct injection engine fuel injector directly determines the quality of fuel atomization. Small changes in the taper, roundness, and hole wall finish of the hole will change the fuel beam shape and affect combustion efficiency and exhaust emissions. It is difficult to stably prepare zero taper or reverse taper structure by traditional electric spark and mechanical drilling, while femtosecond laser can accurately customize the nozzle hole profile on the cemented carbide substrate of the fuel injector to ensure that the angle and aperture of each microhole are highly consistent, so that the fuel atomization is more uniform and sufficient, which helps the engine to improve thermal efficiency and reduce pollutant emissions. In addition to fuel injectors, micro-nano-texturing of piston skirts is also a typical application. By preparing an orderly micro-groove structure on the surface of the piston, the retention capacity of the lubricating oil film can be improved, the friction loss between the piston and the cylinder wall can be reduced, and the friction resistance can be significantly reduced under the measured working conditions, without changing the basic structure. Improve the durability and fuel consumption performance of the whole machine. The ceramic functional layer inside the oxygen sensor and exhaust temperature sensor also relies on femtosecond laser for fine etching and micropore forming to ensure the response speed and measurement accuracy of sensor signal acquisition, and provide reliable support for the closed-loop combustion control of the vehicle.
For new energy vehicles, femtosecond lasers release great value in the processing of power batteries, drive motors and lightweight composite materials. The copper and aluminum pole pieces and tabs of the power battery are ultra-thin flexible substrates. Traditional die cutting or ordinary laser cutting are prone to burrs and thermal burns. Once the burrs fall off, they will cause an internal short circuit of the battery core, directly threatening the safety of the battery. Femtosecond cold cutting hardly causes thermal damage to the substrate, and the trimming is smooth, effectively reducing the risk of short circuit of the battery core and improving the batch consistency and long-term cycle stability of the battery. For popular lightweight materials such as carbon fiber composite materials, ordinary thermal laser processing is easy to cause resin matrix ablation and fiber drawing delamination, while femtosecond laser can realize synchronous cold removal of fiber and resin, with complete processing section, which is suitable for opening and contour trimming of carbon fiber body cover, battery protective shell and structural connector, and supports the landing of body weight reduction target.
Under the wave of intelligent driving, the precision processing of on-board sensing components further expands the application boundary of femtosecond laser. Laser radar, camera optical window, millimeter wave radar substrate, vehicle optical filter all need micro-nano structure, used to achieve optical functions such as antireflection, light, anti-glare. Femtosecond laser can directly write micro-nano gratings and sub-wavelength structures on the surface of optical glass and infrared materials, without the need for complex processes such as lithography and chemical etching, and the process is more green and controllable. In terms of safety system, the processing of the weakening line of the airbag cover plate is a very test of the process stability, especially the leather and soft composite cover plate, which is easy to change color and embrittlement of the material when heated. Femtosecond laser can accurately control the etching depth. While ensuring the integrity of the appearance of the cover plate, a stable tearing path is set to ensure that the initiation timing and deployment of the airbag conform to safety specifications.
Femtosecond laser marking also has unique advantages at the level of component identification and traceability control. Ordinary laser marking relies on thermal burning, which is easy to cause discoloration and stress damage of the substrate. Femtosecond laser relies on internal modification of the material to realize permanent marking. The marking is clear and wear-resistant, and will not damage the surface coating and mechanical properties of parts. It is suitable for marking the traceability code, two-dimensional code and serial number of key safety parts such as engine crankshaft, battery monomer and sensor, and meets the long-term use requirements of the vehicle quality traceability system.
Of course, at this stage, femtosecond laser also has practical problems such as high equipment cost and limited processing efficiency in large-area processing scenarios. Early femtosecond laser is more used for small-scale production of high-end parts. With the laser power increase, galvanometer and five-axis linkage processing system continues to iterate, the overall cost of equipment gradually downward, more and more mainstream component manufacturers began to build femtosecond laser production lines, the process window is also widening.
Standing at the node of the transformation of the automobile industry, femtosecond laser is not only a single-point processing process, but also the underlying manufacturing capability that supports the iteration of automobiles towards higher energy efficiency, higher safety level and more new material systems. In the future, with the deep integration of femtosecond laser and online visual inspection, closed-loop process control and automated production line, it will continue to penetrate more links such as power system, power battery, intelligent perception, lightweight body, etc., and help automobile manufacturing move forward steadily towards ultra-precision, low-loss and green intelligent manufacturing.
