Although aluminum processing with lasers has become popular in industrial applications, machining some blind grooves or blind holes with a required size in aluminum sheets is also a difficult task for laser technicians. In this paper, blind grooves with the depth of about 0.1 mm and the width of less than 0.1 mm on a 0.24 mm thick aluminum sheet have been realized by using two kinds of nanosecond Q-switched lasers without burning the coating polymer layer. The effects of the laser wavelength, average power, and scanning speed on laser processing have been investigated in detail. The groove machining of aluminum sheets has been carried out at different laser power and machining speeds by use of two Q-switched lasers with the wavelengths of 532 nm and 355 nm. The experiment result shows that the faster the scanning speed, the better the processing efficiency. And the status of blind grooves processed by a 355 nm laser is cleaner and smarter. In summary, the optimal laser parameters for processing grooves on the aluminum surface are the peak power density of 2.27×108 W/cm2 with the scanning speed of 0.1 mm/s for a 355 nm nanosecond laser. The results of our study might be of great importance as a reference for processing blind grooves on aluminum sheets in some industrial applications.

Laser processing plays a key role in the industrial manufacture. The transparent material processing with a visible nanosecond laser based on a tripartite-interaction procedure has proven to be an effective method, which has the advantages of low cost, high efficiency, and simplicity over the traditional direct processing by using a femtosecond laser. In our pre-study, by using an assisted metal foil attached to the rear surface of a transparent glass sheet, some holes can be drilled on the glass sheet with a visible nanosecond laser. Such a physical mechanism is based on the heat conduction, generation of stress and ablation among the laser beam, the glass sheet and the metal foil. However, the processing quality of the glass sheet during the previous process is still dissatisfied and remains to be improved. In this study, we demonstrated a new tripartite-interaction procedure among the laser beam, glass sheet and copper foil, i.e. attaching an assisted copper foil on the front surface of the glass sheet, to further improve the processing quality of the hybrid tripartite-interaction processing. The experimental results are compared with those of our previous work, indicating that drilled holes and grooves with less crack and better quality can be obtained by using the new procedure. Moreover, to analyze the reasons of obtaining less cracks and better quality, we have carried out a series of theoretical studies on simulating such a new tripartite-interaction process. According to some specific simulation results of the temperature and density variations in the glass and copper, we can analyze that the reduction of thermal damage on the glass sheet and the improvement on processing quality might be attributed to the thermal transfer induced by attenuated laser energy in such a configuration. Our results could be useful for the development of visible nanosecond laser processing in industrial applications.

With the development of laser technology, nanosecond lasers have been widely used in material micromachining due to their advantages such as the narrow pulse width and high-power density. The high-order harmonic generation procedures have been invented to obtain 532, 355, and 266 nm radiations based on a 1064 nm Nd:YAG laser. In this paper, the influence of different sample moving speeds and laser power on the cutting effects were studied using three kinds of laser sources.It can be seen that the state of the cutting surface has not changed obviously when the laser power was increased. The selfdefined cutting threshold, i.e., 2.25 W•s/mm, has been obtained by investigating the processing morphology with the power of 1.35 W at different sample moving speeds for both a 355 nm laser and a 266 nm laser. Increasing the laser power to 3.20 W, we obtained the cutting threshold of about 1.80 W•s/mm for a 355 nm laser. The scorching status of the surfaces cut by both a FHG laser and a SHG laser have been found to be more serious than that cut by a THG laser. The experiments have demonstrated that the machining efficiency increases with the laser power, but the cutting quality becomes worse at the same time. The results are thought to be useful for the PCB cutting applications in the industrial fields.

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