Abrasive flow machining (AFM) is a nontraditional surface finishing method that finishes complex surface by pushing the abrasive media flow through the workpiece surface. The entrance effect that the material removal increases at the entrance of changing the cross-sectional flow channel is a difficult problem for AFM. In this paper, the effects of media rheological properties on the entrance effect are discussed. To explore the effects of the media's viscoelasticity on the entrance effect, two sets of media with different viscoelasticity properties are adopted to study their rheological and machining performances in the designed flow channel with a contraction area. The rheological properties are tested by frequency sweep and characterized by the Maxwell viscoelastic model and the Carreau viscous model. In the experiment, the variation of the profile height (ΔH) and the variation ratio of the roughness (ΔRa) on the workpiece surface are measured. Moreover, numerical simulation results under different constitutive equations are compared with the experimental results. It shows that the numerical simulation results of a viscoelastic model have a better agreement with the experimental results than the viscous model, and the increase of the viscoelasticity makes the entrance effect be exacerbated, which can be predicted by the viscoelastic numerical simulation.

Laser bending of silicon sheet is a process to form three-dimensional microstructural silicon elements in an ambient environment. This study aims to investigate the process mechanism with the aid of both experimental and numerical analyses. To this end, a thin-film thermocouple was prepared to capture the temperature field within the heating zone of the laser beam. A new method was then developed to precisely determine the absorption factor by coupling numerical simulation of the laser bending results with the experimental results. It was found that each laser pulse causes a cycle of sharp temperature rise-drop in a silicon sheet. When the temperature in the heating zone is low, the sheet deforms elastically. When it is beyond the brittle–ductile transition temperature of silicon, however, plastic deformation in the sheet takes place and bending occurs. The bending angle becomes larger with increasing the number of laser beam scanning, once the temperature gradient in the scanning area is large enough.

Compared with the single-component metal plate, there is a special transition layer on the joint interface between two kinds of materials in the stainless steel-carbon steel laminated plate (SCLP). In order to describe the finite element model of laser bending accurately, it is of great significance to determine material properties of the transition layer. Based on the element distribution, an equivalent method is adopted to calculate thermal conductivity, thermal expansion coefficient, elastic modulus, density, Poisson’s ratio, and specific heat capacity of transition layer. The electron probe experiments show that the transition layer is formed by interfacial element diffusion with thickness of 7 μm. Besides, the volume fraction of stainless steel (46.63%) and carbon steel (53.37%) in the transition layer is tested by energy dispersive spectrometer, respectively. Through the equivalent method, a laser bending model of SCLP is simulated by ANSYS software to predict the bending angle under different parameters. The experimental verification shows that the maximum of bending angle errors is 3.74%, which is lower than the maximum 4.93% of errors calculated by the mean value method. The analysis verifies that the laser bending model is feasible and contributes to improving the accuracy of modeling SCLP in the laser bending process.

To study the regular pattern of vapor-to-melt ratio in laser cutting sheet metal, a physical model of vapor-to-melt ratio is developed to demonstrate the material remove forms of vaporization-melt in cutting area and the state of energy and mass flow in the molten layer. Variation of vapor-to-melt ratio with laser power and cutting velocity is obtained by laser cutting of 6063 aluminum alloy sheet. The 0.5-mm sheet thickness is carried out on a JK701H Nd:YAG pulse laser cutting system by simulating under the regression correction of cut radius. Observation on the cut samples with different parameters (65 W, 85 W, 105 W varied with laser power increasing, and 2.2 mm/s, 2.0 mm/s, 1.8 mm/s with decreasing of beam cutting speed) and the calculations show that vapor-to-melt ratio increases (0.595–1.995, 0.672–2.631, 0.787–4.171) with laser power (65 W–110 W) and decreases with cutting velocity (1.8 mm/s–2.4 mm/s). At the same time, the laser cutting quality increases with vapor-to-melt ratio and the decrease with thickness of residual molten layer. The results show good agreement between vapor-to-melt ratio model and experiments. The analysis verifies that this model is feasible and it makes contribution to laser precision cutting.

In order to reveal the relationship between vapor-to-melt ratio and processing quality in pulsed laser cutting of alumina ceramic sheets, experiments are carried out to obtain variations of the vapor-to-melt ratio with laser power, scanning speed, and thickness of ceramic sheet. By the morphological observation and analysis, the influence of the vapor-to-melt ratio on cutting quality is summarized. It is found that the vapor-to-melt ratio is increased with the increase of laser power, while it is decreased with the increase of scanning speed and the increase of sheet thickness. A good processing quality with suitable kerfs' width, better uniformity, and smaller roughness is obtained at a relatively large value of vapor-to-melt ratio. However, the excessive vapor-to-melt ratio will cause the deterioration of cutting stability and quality. Therefore, to meet the requirement, the vapor-to-melt ratio is controlled at around 0.1 to get 250 μm of average kerfs' width and Ra less than 3.2 μm of uniform kerfs. It reveals that the vapor-to-melt ratio is more intuitive to reflect the connection between the forms of material removal and cutting quality in laser processing, which provides an important theoretical and experimental support in the field of precision laser cutting on alumina ceramic sheets.