Fiber Laser Processing Research Articles

Enhancing the Cooling Efficiency of Aluminum-Filled Epoxy Resin Rapid Tool by Changing Inner Surface Roughness of Cooling Channels.

In low-pressure wax injection molding, cooling time refers to the period during which the molten plastic inside the mold solidifies and cools down to a temperature where it can be safely ejected without deformation. However, cooling efficiency for the mass production of injection-molded wax patterns is crucial. This work aims to investigate the impact of varying surface roughness on the inner walls of the cooling channel on the cooling efficiency of an aluminum-filled epoxy resin rapid tool. It was found that the cooling time for the injection-molded products can be determined by the surface roughness according to the proposed prediction equation. Employing fiber laser processing on high-speed steel rods allows for the creation of microstructures with different surface roughness levels. Results demonstrate a clear link between the surface roughness of cooling channel walls and cooling time for molded wax patterns. Employing an aluminum-filled epoxy resin rapid tool with a surface roughness of 4.9 µm for low-pressure wax injection molding can save time, with a cooling efficiency improvement of approximately 34%. Utilizing an aluminum-filled epoxy resin rapid tool with a surface roughness of 4.9 µm on the inner walls of the cooling channel can save the cooling time by up to approximately 60%. These findings underscore the significant role of cooling channel surface roughness in optimizing injection molding processes for enhanced efficiency.

A unique fiber laser processing of Z-A composite under dry, gas, liquid, and solid environments: A competitive ablation efficiency followed by surface analysis

Compared to monolithic ceramics, the Z-A composite exhibits distinct behavior when stressed. It serves to impede the propagation of the crack's endpoint and retains its structural integrity. This intriguing quality makes it a choice for any high-stress supportive application that necessitates robustness, particularly in the medical industry. However, the laser processing of Z-A is quite sophisticated than monolithic ceramic due to its different thermal properties and varying energy absorption rates that are contingent upon the reinforcing material and matrix. The current investigation outlines a unique approach called FLSDM (fiber laser step-down milling) to create the squircle pattern on Z-A (uniquely by laser) for possible implications as a bone scaffold. The present work has also paid close attention to the effectiveness of laser processing factors (LPFs) that might affect the efficacy of ablation under the disparate states of environments like dry, liquid, gas, and solid. Moreover, this article asserts experimental inquisitions for an extensive comparative study on a short-pulse laser ablation efficiency and laser-treated surface (LTS) analysis under disparate environments. The study examines various aspects such as laser-induced surface morphology, crack behavior, crystal structure, bonding pattern, and phase transformation. The current FLSDM methodology exhibits its suitability by offering a possibility for the adoptable configuration on the Z-A to meet scaffold requirements.

Comparative study of process parameters on dross properties by laser machining of AISI 316L material

The main aim of this paper is to examine the impact of process parameters on the dross height formation for CO2 and fiber laser machining of SS 316L material. CO2 and fiber laser machining has a small spot size, narrow beam, high intensity, and depth of focus that are conveniently absorbed by the metal surfaces. The work is concentrated on the experimental study of laser machining of SS 316L material for 20 mm thickness. The cut qualities of the workpiece are analysed by measuring the dross height by changing the process parameters like assist gas pressure, laser power, and cutting speed. The experimentation is performed on Bystronic laser cutting machine. In this study, the DOE technique is used implementing the response surface methodology approach. Three factors and two levels are selected, and the total numbers of test runs are 17. Mathematical calculations are carried out using ANOVA. The optimum values of performance parameters are defined to achieve the required minimum dross height. The experimental analysis identified that the CO2 laser process produces higher cut quality as compared to the fiber laser process. The major inference that is drawn from this study is change in cutting speed affects the dross height. Gas pressure did not show much effect on change in dross height formation.

Study on the behavior of Z-A composite under fiber laser processing in different environments

Fiber laser, as a unique tool, has proven its supremacy in processing implant materials. Being a thermal-based tool, it has some ineptitude against surface functionality, like the development of crack patterns, which is a severe issue that endangers the longevity of orthopedic implants. The medical world has paid close attention to this problem in recent years. In this context, the current study investigates the impact of laser fluence on the crack behavior during the ablation of Z-A (zirconia-alumina) composite under dual environments like ambient air and water. According to the current research’s findings, it has been observed that the Z-A composite acts differently in different environments under the same thermic load. The adverse impact of laser fluence seems to be meager, while Z-A is processed in a wet environment compared to a dry one. As a result, considerable residual stresses support forming of a network of cracks in a dry environment. However, no cracks were seen in the wet medium due to low stress and prolonged fracture toughness. Furthermore, with the support of characterization tools, the crack mechanism under ambient air and water environments is addressed. The findings of this study are expected to minimize the crack growth and the challenges associated with fiber laser-processed surfaces to make it an ideal implant viable for wider clinical adoption.[copyright information to be updated in production process]

Influence of dry and wet environments during fiber laser processing of metallic substrate under a neoteric scan mode

The demand for improved machining productivity and good surface characteristics is of utmost importance in laser micro-machining. This research asserts the pulsed laser micromachining process (PLMMP) to fabricate micro-channels on Fe-Cr-Ni enriched superalloy for heat exchanger applications in the marine industry. As PLMMP is one of the exacting manufacturing processes, this study intends to improve it by introducing a linear orbit-in-orbit laser beam positioning strategy (LO-OLPS) to generate micro-channels. The core goal of this research is to raise awareness of some unique parameters and their potential consequences on the major characteristics, like dimensionality, material ablation, and surface irregularities. By tweaking the MDPSS fiber laser scan modes, the current method was examined under dry and wet conditions as a distinct industrial potential. Apart from these, metallography analysis, including phase quantifications, elemental analysis, surface morphology, functional group identification, and micro-hardness (µH) studies akin to crystallite size (D) and lattice strain (ε), were scrutinized on D-PLPS and W-PLPS. In both conditions, the obtained γ-phase is similar to the base substrate, but in D-PLPS, an additional peak named CrO2 was obtained from XRD results. D values are lower in dry (D-PLPS) than in wet pulsed laser processed surface (W-PLPS), while µH and ε values are higher in D-PLPS. EDS results revealed that element like oxygen was found to be more abundant on the D-PLPS than on the W-PLPS, while carbon content is slightly copious in the case of W-PLPS compared to the D-PLPS. Furthermore, both environments had molecular bond displacement relative to the base material.

Pulsed fiber laser processing of A4 SS under active and inactive environments: A comparative study

Higher machining productivity and improved surface functionalities are major concerns in laser micromachining. A pulsed fiber laser process (PFLP) is asserted in this study for producing micro-channels on A4 stainless steel (A4 SS) for marine applications. As PFLP is one of the most demanding manufacturing processes, this research aims to enhance PFLP by introducing a novel linear orbit-in-orbit laser beam position approach (LO-OLPA). This innovative method was further investigated in active and inactive gas environments as an existing industrial potential by altering the PFLP variables via tailoring the scan modes of the fiber laser. Furthermore, responses such as material ablation, dimensional, and surface characteristics were compared. The response functions were then used for multi-response whale optimization (MRWO) to acquire the best parametric settings for both environments to enhance productivity and quality. Later, surface analysis (such as surface morphology, elemental diffusions, phase quantifications, and molecular bond identification) was studied in two environments. The results demonstrated that the exothermic chemical reaction boosted the material ablation and dimensional aspects of A4 SS during PFLP but impaired the surface quality when the environment switched from inactive to active. Also, in both conditions, the entry side of the channels is rich in Fe and Cr oxides, but the exit side has just Cr oxide. Elements including Cr, and Fe were revealed to be more abundant in the evacuated molten materiallayer under inactive compared to the active environment. In addition, molecular bond displacement was detected in both environments compared to the base material.

Laser-Assisted Ultrafast Fabrication of Crystalline Ta-Doped TiO2 for High-Humidity-Processed Perovskite Solar Cells.

A titanium dioxide (TiO2) compact film is a widely used electron transport layer (ETL) for n–i–p planar perovskite solar cells (PSCs). However, TiO2 sufferers from poor electrical conductivity, leading to high energy loss at the perovskite/ETL/transparent conductive oxide interface. Doping the TiO2 film with alkali- and transition-metal elements is an effective way to improve its electrical conductivity. The conventional method to prepare these metal-doped TiO2 films commonly requires time-consuming furnace treatments at 450–600 °C for 30 min to 3 h. Herein, a rapid one-step laser treatment is developed to enable doping of tantalum (Ta) in TiO2 (Ta-TiO2) and to simultaneously induce the crystallization of TiO2 films from its amorphous precursor to an anatase phase. The PSCs based on the Ta-TiO2 films treated with the optimized fiber laser (1070 nm) processing parameters (21 s with a peak processing temperature of 800–850 °C) show enhanced photovoltaic performance in comparison to that of the device fabricated using furnace-treated films at 500 °C for 30 min. The ambient-processed planar PSCs fabricated under high relative humidity (RH) of 50–70% display power conversion efficiencies (PCEs) of 18.34% and 16.04% for devices based on Cs0.1FA0.9PbI3 and CH3NH3PbI3 absorbers, respectively. These results are due to the improved physical and chemical properties of the Ta-TiO2 films treated by the optimal laser process in comparison to those for the furnace process. The laser process is rapid, simple, and potentially scalable to produce metal-doped TiO2 films for efficient PSCs.

Microstructural, hardening, and wear characteristics of surface re-melted AISI 410S stainless steel via fiber laser process

Microstructural, hardening, and wear characteristics of surface re-melted AISI 410S stainless steel via fiber laser process

Understanding the surface integrity of laser surface engineered tungsten carbide

The study investigated the effect of fibre laser processing (1060 nm, 240-ns pulse duration) on the surface integrity of tungsten carbide (WC). The induced surface damage ranged from crack formation, porosity, balling, to spherical pores; the severity and presence of each were dependent on the laser parameters selected. The influence of fluence (0.05–0.20 J/cm2), frequency (5–100 kHz), feed speed (250–2500 mm/s) and hatch distance (0.02–0.06 mm) on 2D and 3D surface roughness were analysed using the Taguchi technique. Fluence, frequency, and the interaction effect of these were the most influential factors on the surface integrity; from this a linear model was generated to predict the surface roughness. The model performed best at moderate to medium level of processing with an error between 1 and 10 %. The model failed to predict the material response as accurately at higher fluences with percentage errors between 15 and 36 %. In this study, a crack classification system and crack density variable were introduced to estimate the number of cracks and crack type within a 1-mm2 area size. Statistical analysis of variance (ANOVA) found that fluence (63.49%) and frequency (29.38%) had a significant effect on the crack density independently but not the interaction of both. The crack density was minimised at 0.149 J/cm2 and 52.5 kHz. To the author’s knowledge, for the first time, a quantitative analysis of the crack formation mechanism for brittle materials is proposed (post laser processing).

Synthesis of nanograiny SnO2 films on laser-patterned graphene/ceramic substrates for low-temperature ethanol gas sensors

This study proposed a facile low-cost sol-gel method to synthesize nanograiny SnO2 films on laser-patterned graphene/ceramic substrates for ethanol gas detection at a low working temperature. A high pulsed fiber laser processing system was used to pattern interdigitated and triangular electrodes on the sensing and heating layers, respectively, of the graphene/ceramic substrates. The synthesized SnO2 had nanograiny structures and irregular micro-/nano-holes on the film surface. Thus, the synthesized SnO2 films had increased surface area and volume ratio. In addition, graphene-based electrode structures were patterned using the following optimum laser machining parameters: pulse repetition frequency of 750 kHz, pulse width of 4 ns, scan speed of 50 mm/s, scanning pitch of 0.01 mm, areal fluence of 982 J/cm2, and one patterning pass. For ethanol gas detection, the nanograiny SnO2 sensors showed the best response of 3.18% for an ethanol gas concentration of 1000 ppm at a working temperature of 84 °C. Furthermore, the response and recovery times were calculated to be approximately 13 s and 4 s, respectively. The developed gas sensors exhibited an excellent response and short response and recovery times at low working temperatures.

Investigation of the laser cleaning process for IBS grids in optical coating technology

The ion-beam sputtering (IBS) grid laser cleaning process is described as an alternative to manual cleaning and sandblasting in terms of surface morphology, roughness, and speed. It has been demonstrated that nanosecond fiber laser processing can be successfully used for controlled cleaning of complex grid surfaces at high speed and low surface impact, which is important for increasing the life of expensive parts. Under optimal conditions for single-pass processing, the scanning speed in the focal plane of a 160 mm F-Theta lens was 8 m/s at a laser pulse energy of 300 μJ, a pulse width of 120 ns, and a repetition rate of 100 kHz.

A Study of Fiber Laser Micro-Grooving of 316L Stainless Steel at Different Temperatures

The present article deals with the generation of micro-grooves on 316L stainless steel (SS) by a nanosecond pulsed fiber laser system. Fabrication of micro-grooves on 316L SS has immensely contributed to the biomedical and automotive industries through improving the mechanical, lubrication, and corrosion resistance properties. In the present work, the considered process parameters are the preheating temperature (100°C and 200°C), along with the room temperature (24°C), cutting speed, sawing angle, pulse frequency, and laser power. The ranges of cutting speed and sawing angle are 0.1–1.1 mm s−1 and 0.1°–1°, respectively. Besides, pulse frequency and laser power vary from 55 kHz to 85 kHz and from 15 W to 45 W, respectively. The constant parameters are the pulse width of 99% and assist air pressure of 6 kgf cm−2. The variable parameters for the analysis are cut width and heat-affected zone (HAZ) width. The article aims to showcase a comprehensive study of fiber laser process parameters at different temperatures (preheated condition and room temperature) with variable sawing angles to produce better process control and bring about each considered process parameter’s critical value. The experimental results show that higher dimensions of cut width and HAZ width are observed at 200°C with the increment of sawing angle and laser power, compared to other temperatures. With the increment of cutting speed and laser power, the HAZ width tends to rise sharply. A significant drop in cut width and HAZ width dimensions is observed with the increment in pulse frequency for any temperature.

Ultrafast and Scalable Laser‐Induced Crystallization of Titanium Dioxide Films for Planar Perovskite Solar Cells

A conventional annealing method to fabricate metal oxide films used for perovskite solar cells (PSCs) is a time‐consuming batch process. Herein, a near‐IR fiber laser process with a unique design of power ramping program and beam configuration is developed to achieve ultrafast and scalable processing of TiO2 films for PSCs. Highly crystalline anatase TiO2 films can be synthesized in only 18.5 s by the laser process with a peak annealing temperature up to 800–850 °C, compared with that of the furnace‐annealing at 500 °C for 30 min and an overall processing time of 3 h. Then, a unique capability of using this laser process is presented to anneal stacked layers of substrates coated with the TiO2 films simultaneously, with a uniform annealing area up to 15.2 cm2, thereby potentially achieving an in‐line production rate of over 43 cm2 min−1 (1 cm2 in ≈1.4 s). Planar PSCs fabricated under a high relative humidity of 60–70% based on the TiO2 films annealed under optimal laser conditions show enhanced photovoltaic performance than the furnace‐annealed samples. This laser process potentially opens a new avenue for scalable annealing and rapid production of thin films.

Parametric influences of fiber laser micro-machining for the generation of micro-channels on PMMA

Fiber laser micro-channeling on polymethyl methacrylate (PMMA) workpiece has been carried out to determine the effect of process parameters as well as optimum values of the responses, i.e., cut width and depth of the fabricated micro-channels. Response surface methodology-based analysis has been carried out by conducting experiments as per experimental design by varying scan speed of 10–30 mm/s; pulse frequency from 50 to 90 kHz; laser power of 5–15 W and the number of pass from 1 to 5. The mechanism behind the fiber laser-fabricated micro-channels on PMMA at 1064 nm wavelength has been discussed and analyzed. A sensitivity analysis of the process parameters on cut width and depth has also been carried out to determine the critical parameter influencing the micro-channel geometry. The experimental results show that the sensitiveness of both cut width and depth are maximum for the number of passes as compared to the other process parameters. Finally, at an optimum combination of process parameters, the optimal values of cut width, and depth are achieved as 145.34 µm and 445.50 µm, respectively. Concerning the optimal values of the responses, the mean percentage errors are calculated below 5% from the optimized combination of process parameters. The present research work provides a technical guideline of fiber laser processing on PMMA at a fundamental wavelength.

Tailoring Tribological Performance of Pure Titanium by a Duplex Treatment of Laser Surface Texturing-Thermal Oxidation

A combined surface treatment of laser surface texturing (LST)-thermal oxidation (TO) technique was performed on pure titanium (TA2) matrix to enhance its wear resistance. The dimple-shaped texture was fabricated by using an optical fiber laser processing equipment, and the dimple-shaped texture with diameter of 300 μm and density of 5%. The thermal oxidation coating (TO-coating) was prepared by TO treatment under 650 °C for 30 h. Microstructure, microhardness, and bonding strength of the TO-TA2 were systematically characterized. Comparative evaluation of anti-wear performance for relevant samples of duplex treatment TA2 (DT-TA2), LST-TA2, TO-TA2, and TA2 matrix were investigated via the dry sliding process. The results revealed that uniform and dense TO coating with a thickness of approximately 11 μm was fabricated on the surface of the TA2 matrix. The attained TO coating consisted of the compound phase of TiO2 shown by XRD detection. The surface hardness and elasticity modulus of the TA2 were improved by TO treatment, and the attained TO coating had a strong bonding strength with the TA2 matrix. In terms of wear rate, the samples were sorted in the following order: DT-TA2 < TO-TA2 < LST-TA2 < TA2. For tribological behavior, the duplex treatment process can significantly reduce the abrasive wear and adhesive wear tendency of the TA2 matrix. Taking advantage of LST and TO treatment, the wear resistance of TA2 sample after duplex treatment was significantly improved. In view of this, the TO coating is expected to provide wear resistance protection for pure titanium components, the presence of dimples reduced the friction coefficient of pure titanium components, and further extended their service life. The results may provide reference data for surface modification of TA2 by the laser surface texturing and thermal oxidation duplex treatment.

Hydrophilic to ultrahydrophobic transition of Al 7075 by affordable ns fiber laser and vacuum processing

A lot of research efforts have been invested in the fabrication of superhydrophobic surfaces in recent years due to many protentional applications in science and industry including anti-icing, self-cleaning and anti-corrosive surfaces. Laser as a non-polluting, precise and flexible tool can be applied to replicate surface microstructures of extremely water repellent lotus leave surface. In this study, a common nanosecond laser source is used to fabricate a super/ultrahydrophobic surfaces with different microstructure designs, contact angles above 170° and sliding angles below 5°. The freshly processed surface is hydrophilic and becomes hydrophobic and superhydrophobic in a certain time period, which could be dramatically reduced by storing samples in high vacuum. The transformation in wetting properties are analysed with respect to surface geometry and surface chemistry.

Optimizing Automotive Welding Applications with CleanWeld

AbstractCleanWeld is a unique combination of fiber laser innovation, beam delivery, and process knowledge, which improves part quality, increases throughput, and lowers process costs. It optimizes welding processes to weld zero‐gap galvanized steel, (high‐strengthened) stainless steel, copper, and aluminum with up to 80 % less spatter, lower porosity, and no cracking. In certain welding processes it allows best performance with up to 40 % less laser power.

ANALYSIS OF LASER PROCESSING OF ARTIFICIAL LEATHER

With the development of laser technologies, the field of application of lasers is developing as well. They are capable of processing numerous materials and are still finding their application in unexpected areas. In this case, lasers are studied as a system with which black and white color artificial leather can be processed. This modern material allows you to combine comfort, practicality and reasonable price in a finished product. The manufacturer of artificial leather provides wide possibilities of design. In this study laser beam was used for dark and light laser markings on black and white color artificial leather and in this work, it could be observed how CO2 and fiber laser processing influence this specific material.

Fiber laser processing of GFRP composites and multi-objective optimization of the process using response surface methodology

In the present investigation, a continuous wave fiber laser with maximum power of 400 W was used to cut a glass fiber reinforced plastic sheet of 4.56 mm thickness using Nitrogen as assisting gas. The influence processing parameters such as laser irradiance, gas pressure, and cutting speed on the cut surface quality were investigated by using response surface methodology. The different responses of laser cut surface such as upper kerf width, taper percentage along the cut depth, and heat-affected zone on the top surface were measured to analyze the influence of input process parameters on the responses. A statistical analysis on the obtained results was conducted and found that the optimum values of different input process parameters were laser irradiance: 8.28 × 105 watt/cm2, cutting speed: 600 mm/min and assisting gas pressure: 7.84 bar. The corresponding values of responses were upper kerf width: 177.4 µm, taper 0.73%, and heat-affected zone on top surface: 109.23 µm. The confirmation experiments were conducted with the obtained optimum parameter setting and observed that the predicted values and experimental values for upper kerf width, taper percentage and top surface heat-affected zone were within the error limits of 2.52%, 1.84%, and 0.45%, respectively. Furthermore, damages like loose fibers, interlayer fractures, evaporation of matrix material and fiber breakages were observed.

Magnetic losses reduction in grain oriented silicon steel by pulse and continuous fiber laser processing

The present paper shows the impact of different laser scribing conditions on possible reduction of magnetic losses in grain oriented electrical steel sheets. The experimental Fe-3%Si steel was taken from industrial line after final box annealing. The surface of investigated steel was subjected to fiber laser processing using both pulse and continuous scribing regimes in order to generate residual thermal stresses inducing the magnetic domains structure refinement. The magnetic losses of experimental samples before and after individual laser scribing regimes were tested in AC magnetic field with 50Hz frequency and induction of 1.5T. The most significant magnetic losses reduction of 38% was obtained at optimized conditions of continuous laser scribing regime. A semi quantitative relationship has been found between the domain patterns and the used fiber laser processing.