Effects Of Laser Processing Parameters Research Articles

Removal mechanism of 2.5-dimensional carbon fiber reinforced ceramic matrix composites processed by nanosecond laser

C/SiC composite material is widely used in aerospace fields because of its excellent properties; however, it is difficult to be removed and processed. In this paper, the 2.5-dimensional C/SiC composite material was ablated by nanosecond laser to explore the laser removal mechanism. Firstly, the laser ablation experiment was carried out to investigate the gradual process of ablation morphology with the increasing laser power density. Secondly, the characteristics of ablation holes were analyzed, and the effects of laser processing parameters and fiber orientation on the ablation morphology and size were studied. In addition, the ablation morphology of needle-punched fiber area was analyzed to expound the unique ablation removal characteristics of 2.5-dimensional C/SiC composites. At last, ablation removal mechanism of 2.5-dimensional C/SiC composites was summarized, and the model of ablation removal process was established. The results indicated that ablation morphology was evolved from nothing to ablation mark, to fiber expansion, to fiber shrinkage and tension, to resolidification, to removal holes, and to increasing holes with laser power density. Besides, the ablation morphology in needle-punched fiber area was different from elliptic ablation morphology in the 0° or 90° fiber area, the ablation holes in the needle-punched fiber area were smaller and deeper, and the ablation holes were approximately circular. The results would provide theoretical basis and technical support for processing functionalized structure of 2.5-dimensional C/SiC composites by nanosecond laser, such as blind holes, grooves, and square holes.

Effect of Laser Processing Parameters on Microhole Quality of Aluminium Nitride Ceramics

A picosecond laser in spin-cutting mode was used to drill 500μm diameter microholes on 150μm thick aluminium nitride ceramic. The effects of laser processing parameters such as the laser power, scanning speed, and defocus amount on the microhole quality were studied. The results show that as the laser power increases, the inlet and outlet diameters of the holes increase, the taper decreases slightly, and the thickness of the recast layer decreases evidently. The scanning speed has no obvious effect on the diameter and taper of the hole; however, the hole can not be drilled through when the speed is too large. Positive defocus can effectively reduce the taper of the hole. Under 28.5W laser power, 400Hz frequency, 200mm/s scanning speed, and zero defocus amount conditions, high-quality microholes with a taper of 0.85° were obtained.

Experimental investigations of laser machining process parameters using response surface methodology

The geometrical feature kerf deviation is an undesirable characteristic during machining which is required to be minimized. To minimize kerf deviation characteristics, it is important to select proper machining parameter for machining the workpiece material. Therefore, an investigation is carried out to see the effect of laser process parameters, i.e., “laser power”, “cutting speed”, “gas pressure”, “working distance” and “focus position” on the desired characteristics i.e top kerf deviation and bottom kerf deviation. To achieve the current objective, an experimental investigation is done on CNC based Prima 4000 W CW-CO2 laser cutting process to machined Hastelloy C- 276 material. Using desirability approach of RSM for material Hastelloy C276, the value of the optimum responses top kerf deviation and bottom kerf deviation obtained are 0.0092 mm and 0.0081 mm respectively. The corresponding value of error obtained as 9.7% and 8.6% respectively. Finally, confirmatory test are performed to validate the result obtained using desirability analysis of RSM. The result of confirmatory test shows that percentage error is<10%.

Manufacturing of anti-fogging super-hydrophilic microstructures on glass by nanosecond laser

In this paper, a nanosecond laser processing method with the support of light-absorption auxiliary materials was developed to fabricate anti-fogging super-hydrophilic microstructures on glass substrate surfaces. Through adjusting the focal point offset, the laser was focused on the auxiliary material layer, thus the laser energy required for micromachining was precisely controlled. As a processing example, a bionic honeycomb structure was successfully manufactured by this method. The effects of laser processing parameters on the size and integrity of the fabricated microstructures and on the light transmission of the machined surface were investigated through laser machining experiment. The results indicate that lower power and frequency is the key to obtaining regular honeycomb structures in laser machining. The laser focal point significantly affects the light transmittance of glass, while the feed rate has little effect. The water droplet contact angle was measured to evaluate the hydrophilicity of glass specimens with different dimensions of microstructure. It was found that the contact angle decreased with reduction of the honeycomb structure size.

Effect of laser processing parameters on spectral characteristics of silver-impregnated titanium dioxide thin films

Subject of Research. Local and precise control of nanocomposite material optical properties become possible due to lasers. Laser irradiation can be used as an instrument for the fabrication and modification of such materials. However, for practical applications, it is necessary to know how laser processing parameters impact on spectral characteristics of composite materials which, as a rule, are related to sizes and distribution of nanoparticles. The paper presents research results of the laser processing parameters impact on the reflection spectra of nanocomposite material based on titanium dioxide. Methods. Sol-gel titanium dioxide thin films impregnated with small (less than 5–7 nm) silver nanoparticles on glass slides were exposed to a 405 nm ultraviolet laser. Changes in the sample reflection spectra after laser processing in the continuous wave mode were studied via optical spectrophotometry in the range of 350–760 nm. Main Results. An array of laser tracks on the sample surface was recorded with such processing parameters as the scanning speed and average radiation power. Each track had central and edge areas which were visually observed. Experimental data analysis showed that there was a shift in the reflection spectra peak position in these two areas in the range of 380–440 nm. In order to determine the reasons for such spectral changes, numerical modeling was carried out using the effective medium model in the Bruggemann-Bergman approximation. It was found that the size and distribution of silver nanoparticles at the edges and in the center of the laser processed area may vary. The scanning speeding-up and the average radiation power decrease leads to an increase of nanoparticles size. These size changes occur due to various temperature distributions. Practical Relevance. Control methods for spectral characteristics of sol-gel silver-impregnated titanium dioxide thin films via local laser resizing of nanoparticles are demonstrated. The obtained results are promising for a number of applications: integrated optics, photonics devices, biosensors, photocatalytic devices, and security labels.

Formability and hardness studies of selective laser melting of GH4169 Ni-based alloy powders

Selective laser melting (SLM) is a new three-dimensional printing technology capable of directly manufacturing metal end products and near-end products. Currently, the processing of nickel (Ni)-based alloy powders by SLM technology has not been reported yet. Considering this, this paper lays the foundation for developing relevant SLM technology by experimenting with GH4169 nickel-based alloy powders using an LWY400P laser. The paper deals primarily with single-layer, single-path and single-layer, multipath scan processes in order to explore the mechanisms of the effects of laser process parameters (e.g. current, frequency, pulse width, scan speed and scan spacing) on the formability of GH4169 nickel-based alloy powders. Process optimization was carried out as well. The optimized SLM process involved a parameter group comprising a 140 A laser current, a 150 mm/min scan speed, a 0.35 mm scan spacing, a 5.5 ms pulse width, a 12 Hz frequency and a 0.15 mm coating thickness. Under the optimized parameter group, a 427 HV microhardness was observed. Meanwhile, the formed products had a basically flat surface, a uniform microstructure and a high density.

Thermal behavior and microstructure evolution mechanism of W-20%Fe alloy fabricated by laser metal deposition

A three-dimensional finite element method (FEM) model was established to study the effects of laser processing parameters on the thermal behavior, melting/solidification mechanism, and microstructure evolution during laser melting deposition (LMD) of W-20%Fe alloy, considering the temperature-related thermal physical properties, multiple heat transfer, and latent heat of phase change. It was shown that there was a positive correlation between the maximum temperature and the laser powers. As the laser power increased, the cross-sectional configuration of the molten pool became deeper and narrower. The solidification characteristics, dependent on the solidification growth rate, R, and the temperature gradient, G, were obtained to predict the morphology and scale of the solidified microstructure. The maximum temperature gradient in the molten pool was slightly increased from 1.52×106°C/m to 2.09×106°C/m, as the laser power increased from 800 W to 1100 W. When the laser power was 1000 W and the scanning speed was 400 mm/min, the G/R elevated considerably from top to bottom region of the molten pool about 5.542°Cs/mm to 1829°Cs/mm. The columnar dendrites and the equiaxed dendrites were obtained at the bottom and top regions of the molten pool, respectively. The columnar dendrites were observed at the edge of the molten pool, which was attributed to the high G/R (2.09×109°Cs/mm). The corresponding LMD experiment was carried out, which demonstrated that the established physical model was reliable and accurate.

Thermal Behavior and Densification Mechanism during Selective Laser Melting Additive Manufacturing of Metal Powder

Herein, based on the ABAQUS commercial finite‐element analysis (FEA) software, a set of user subroutines is designed, and then a 3D FEA model is proposed to systematically and quantitatively investigate the effects of laser processing parameters on the evolution of molten pool structure and complicated thermal behavior during the selective laser melting (SLM) additive manufacturing of H13 die steel. The SLM experiments are conducted to verify the accuracy and reliability of simulation and reveal the densification behavior of SLM‐fabricated H13 die steel parts. The underlying thermal mechanism is revealed, and the relationship among laser processing parameters, thermal behavior, and densification is established. It is found that the densification behavior is highly sensitive to the applied volume energy density (VED). The densification level is effectively controlled by adjusting VED, hence obtaining the parts with excellent performance. The SLM‐fabricated specimens with nearly full dense cross sections are obtained, as the applied VED increases to 111 J mm−3. Research results found herein lie a foundation for the actual SLM processing of H13 die steel and provide a theoretical basis and technical support for the laser rapid prototyping of other die steels or even complete die parts.

Effect of Laser Process Parameters on the Microstructure and Properties of TiC Reinforced Co-Based Alloy Laser Cladding Layer

Effect of Laser Process Parameters on the Microstructure and Properties of TiC Reinforced Co-Based Alloy Laser Cladding Layer

Establishment of micropit diameter prediction models based on the support vector machine optimization

Many studies on microtextures have focused on the effect of laser processing parameters on microtextured morphology from the experimental point of view, and not on its influence on the physical field and stress field around the microtextures. This has resulted in the lack of accurate predictions on micropit diameters, thus reducing the processing efficiency. In order to address these problems, the effects of laser processing parameters on the precision machining, physical field, and stress field of micropit textures for a ball-end milling cutter were studied by experiments and simulation. The optimum laser processing parameters include laser power of 70%, scanning speed of 1700 mm/s, and scanning of seven times. Based on the optimized data of a support vector machine, the prediction models of micropit diameters for laser machining were established. The errors of the models are less than 10%, thus verifying their accuracy. This study can serve as a theoretical reference for the efficient processing of titanium alloys.

Application of Response Surface Methodology for Modeling of Laser Transformation Hardening of Commercially Pure Titanium ASTM Grade3

In the presented study, the laser transformation hardening of commercially pure titanium sheet material of thickness being 1.6mm is investigated using CW, 1.6 kW solid State Nd: YAG laser. A Full Factorial Design (FFD) with Response Surface Methodology (RSM) is employed to establish, optimize and to investigate the relationships of three laser transformation hardening process parameters such as laser power, scanning speed, and focused position on laser hardened bead profile parameters such as hardened bead width, hardened depth, heat input and power density. In this work, Laser Transformation Hardening (LTH) with high precision and an optimum desired minimum value of hardened depth of 241 microns has been accomplished with heat input = 150 J/cm and power density = 294.08 W/mm2 for the laser process parameters of lower beam power: 750 Watts, high scanning speed: 3000 mm/min and a defocused beam of –30 mm. Effects of laser process parameters on laser hardened bead geometries were carried out using RSM. Results indicate that the scanning speed has a positive effect on all hardened bead dimensions while the laser power has a positive effect particularly on hardened bead width as compared to hardened depth and heat input. The optimum laser hardening conditions are identified sequentially to minimise hardened depth, heat input, power density and maximum hardened bead width. The validation results demonstrate that the developed models are accurate with low percentages of error.

Micro-Nano Fabrication of Self-Aligned Silicon Electron Field Emitter Arrays Using Pulsed KrF Laser Irradiation

Self-aligned silicon micro-nano structured electron field emitter arrays were fabricated using pulsed krypton fluoride (KrF) excimer laser crystallization (ELC) of hydrogenated amorphous thin silicon films (a-Si:H) on metal coated backplane samples. We investigate the effect of laser processing parameters on the growth of micro-nano conical structures on the surface of the thin silicon films. Randomly oriented conical structures as high as 1 µm were fabricated using laser pulse frequency of 100 Hz and sample stage scanning speed of 0.25 mm/sec. Best field emission (FE) results were measured from samples with the highest surface features with FE currents in the order of 10−6 A and low turn-on emission threshold of ∼14 V/µm. Light emission from the prototype demonstrators was tested using bespoke driver electronics and planar anodes coated with indium tin-oxide (ITO) and medium voltage FE phosphors, to exemplify their usage for future flat panel display technologies.

激光工艺参数对离体皮肤显微组织特征的影响

激光工艺参数对离体皮肤显微组织特征的影响

Effect of process parameters on the microstructure evolution of laser surface quenched Ni-Al bronze

Laser surface quenching technology was used to modify the surface microstructure of as-cast Ni-Al bronze (NAB). The modified microstructure was studied by scanning electron microscopy (SEM), and the effect of laser process parameters on microstructure evolution was investigated. It was found that a fine-grained zone with fully [Formula: see text] phase microstructure formed on the surface of NAB. The depth of the fine-grained zone increased with the increase of laser power, and surface melting occurred when the power reached a threshold value. Laser scanning at a low rate caused the coarsening of grain boundary, while too high rate led to incomplete quenching. Spot overlap ratio determined the microstructure of the superimposed area, and unsuitable ratio would cause bulky [Formula: see text] precipitation at the grain boundary or incomplete transformation from [Formula: see text] phase to [Formula: see text] phase.

Analytical Study on Pulsed-Laser Processing for Acrylonitrile Butadiene Styrene/ PolyVinyl Chloride

This study developed a model involving the energy balance and decomposition at the ablated interface due to the heat transport, optical decomposition and activation energy in Acrylonitrile Butadiene Styrene/PolyVinyl Chloride (ABS/PVC). The prediction for ablation depth obtained from this study is compared with the available experimental data. The predicted results agree with the measured data. The effects of laser processing parameters, optical and thermal properties of ABS/PVC on the variation of the laser-ablated depth with the laser fluences are also discussed. The results validate that the pulsed-laser ablation rate at the initial short period is dominated by optical penetration absorption for laser and is linearly proportional to the logarithm of the laser fluence by a ratio factor “optical absorption length” (i.e., the ablation rate follows Beer’s law at the initial short period).

Effect of laser processing parameters on the efficiency of material: a review in industrial application field

Effect of laser processing parameters on the efficiency of material: a review in industrial application field

Influence of laser process parameters on the characteristic of 30CrMnSiA steel substrate and adhesively bonded joints

The effect of laser process parameters including single pulse energy (E), dimples per square millimetre (D) and laser incidence angle (θ) on the properties of 30CrMnSiA steel substrate and the tensile shear strength of adhesively bonded joints was investigated. The characterization of the substrate was established by surface morphology, the dimension (diameter and depth) of dimples and surface roughness (Ra and Rz). Single lap joints were fabricated and tensile tests were then performed. The fracture surfaces were observed and analyzed. The results indicated that the dimple dimension and surface roughness increased as the single pulse energy increased. The increase of dimples per square millimetre made surface roughness improve. The larger incidence angle reduced the actually absorbed energy changing the shape and size of dimples. The diameter of dimples increased while the depth decreased as incidence angle increased. The modified substrate morphology as well as increased dimple dimension expanded the contact area between the adhesive and adherend. The shear strength was enhanced and the maximum value was 24.67 MPa increasing by 363% compared to the adhesive joints without surface treatment. The mechanical interlocking between the adhesive and laser textured morphology was discovered in the fracture surface demonstrating the improvement of shear strength.

Microstructure and mechanical properties of additive manufactured W-Ni-Fe-Co composite produced by selective laser melting

Tungsten composites face severe challenges in machining complex structures due to tungsten's high melting temperature. To explore solutions that enable fabrication of complex W composite parts by additive manufacturing, W-6Ni-2Fe-2Co (W90), W-12Ni-4Fe-4Co (W80) and W-18Ni-6Fe-6Co (W70) composites were consolidated by selective laser melting (SLM). The effects of laser process parameters and chemical compositions on densification, microstructures, phases, and tensile properties were investigated. With the increase of laser energy density, the density of the composite increases. Near full density with an absence of cracks and pores was achieved in the SLM-processed W70 composites. The typical microstructure consisted of un melted polyhedral W particles and the surrounding W-Ni-Fe-Co matrix with W dendrites. Alternating layered fine dendrite and coarse dendrite zones were visible in side views of the composites. The tensile properties of the W70 composite had a pronounced improvement with the increase of laser energy density. A maximum ultimate tensile strength of 1198 MPa was obtained in the SLM-processed W70 composite with elongation of 9.5%. The SLM-processed W-Ni-Fe-Co composites pave the way for new refractory metal alloys and complex shaped parts fabrication by additive manufacturing.

Effect of Laser Processing Parameters on Cut Quality after Engraving

Abstract The article deals with the quality evaluation of engraved surfaces of selected materials after application of CO2 E4060 laser. A machined steel was chosen steel ČSN 11 373, engraving was carried out on aluminium alloy EN AW 7075, plexiglass XT, plywood and cardboard. Engraving was performed under predetermined power conditions and laser feed rates. Marking of metallic materials was made after applying the marking paste LMM 6000. The evaluation was made on the basis of a visual inspection and then a suitable combination of parameters was chosen for individual materials.

Process optimization of electrolyte-assisted ultraviolet laser machining of ceramic microhole

Electrolyte assisted ultraviolet laser machining (EULM) is presented in this study. First, ceramic material is removed by multiphoton absorption of ultraviolet laser under electrolyte, and ceramic microhole without recast layer is obtained. Meanwhile, the etched material can be carried away by the collapse of cavitation bubbles, and machining quality is higher. Second, process optimization method of EULM is given. The prediction model, which is founded by response surface methodology, is used to analyze the effects of laser process parameters on experimental results. The process optimization model is established based on the prediction values of experimental results. The optimal process scheme is found by simulated annealing algorithm. The experimental results show that the optimization results are reasonable. Moreover, ceramic holes, which are machined by the optimal process parameters, also meet the accuracy requirements.