Set Of Laser Process Parameters Research Articles

Predicting and Enhancing the Multiple Output Qualities in Curved Laser Cutting of Thin Electrical Steel Sheets Using an Artificial Intelligence Approach

This study focused on the efficacy of employing a pulsed fiber laser in the curved cutting of thin, non-oriented electrical steel sheets. Experiments were conducted in paraffinic oil by adjusting the input process parameters, including laser power, pulse frequency, cutting speed, and curvature radius. The multiple output quality metrics included kerf width, inner and outer heat-affected zones, and re-welded portions. Analyses of the Random Forest Method and Response Surface Method indicated that laser pulse frequency was the most important variable affecting the cut quality, followed by laser power, curvature radius, and cutting speed. To improve cut quality, an innovative artificial intelligence (AI) approach incorporating a deep neural network (DNN) model and a modified equilibrium optimizer (M-EO) was proposed. Initially, the DNN model established correlations between input parameters and cut quality aspects, followed by M-EO pinpointing optimal cut qualities. Such an approach successfully identified an optimal set of laser process parameters, even beyond the specified process window from the initial experiments on curved cuts, resulting in significant enhancements confirmed by validation experiments. A comparative analysis showcased the developed models’ superior performance over prior studies. Notably, while the models were initially developed based on the results from curved cuts, they proved adaptable and capable of yielding comparable outcomes for straight cuts as well.

Effect of laser surface remelting on Microstructure, mechanical properties and tribological properties of metals and alloys: A review

Surface defects like porosity, cracks, coarse grains, surface roughness, etc. have a huge impact on the strength and performance of materials. Due to this, surface treatments have become an important part in the field of materials to attain certain desirable mechanical properties and surface properties. Surface of parts treated with laser surface remelting exhibits excellent surface and mechanical properties. It is a computer-based technique which provides the advantage of treating selective surfaces. Laser surface remelting tends to enhance corrosion resistance, microhardness, wear resistance, fatigue strength, and tensile strength of the materials. To achieve certain mechanical properties with laser surface remelting, an optimized set of laser processing parameters is essential. Laser surface remelting has become a compulsory treatment for parts manufactured by Additive Manufacturing (AM) processes as these processes provide poor surface, porosity, and hot cracking defects which ultimately affect the performance of parts. This paper critically evaluates the advancements which have been made in the field of laser surface remelting to get better surface quality, improved mechanical and tribological properties.

On the choice of thermal boundary conditions for microstructure modelling of additive processes

Advanced phase-field modelling of LPBF should consider both melting and solidification, because microstructure quantities like the primary dendrite spacing as well as grain orientations typically are inherited across successive layers. This cannot be achieved by considering constant cooling conditions, which however still is state of the art by now. In this work, two different types of thermal boundary conditions that both allow taking the transition between melting and solidification into account have been implemented and compared. For a given set of laser process parameters, the melting and solidification dynamics, melting depth, dendritic microstructure and grain selection have been simulated in 2d for the multicomponent Ni-base alloy ABD®-900AM. It is demonstrated that latent heat release has a significant impact on the thermal conditions at the dendrite tips, and thus on microstructure. The simulation results are discussed by comparison with analytical heat source models, heat balance considerations and experimental results.

Thermal modeling of laser surface micro-texturing: Investigation on effects of laser parameters on dimple-texture dimensions and aspect ratio

Micro-texturing on the rake/flank face of the tool to obtain higher service life has emerged as a promising area of research. Micro-texturing assists in reducing contact area, and in-turn lowering wear and frictional heat. There are several methods to obtain micro-textures on tools. However, the quality of micro-texture depends largely on the manufacturing method used. Laser-induced surface texturing has been found more accurate and a cost-effective solution to enhance tribological properties and efficiency of the cutting tool. Ultra-short laser pulses can produce controlled ablation and micro-textures. However, obtaining accurate and ultra-clean micro-textures on cutting tools depends on the type of laser source, set of laser process parameters, and physical and mechanical properties of the cutting tool material. Several ablation models have been developed to predict the optimized set of laser parameters. This paper illustrates the simulation of laser surface texturing with the help of the finite element model and its experimental validation with a fiber laser. Thermal modeling and 2-D laser ablation have been presented for tungsten carbide (WC) tool material. Dimple textures have been created on the side rake face with equidistant spacing. Laser parameters like frequency and power have been varied to investigate their effect on texture dimensions and aspect ratio. Sample experimental validation results have also been discussed presenting the degree of agreement to simulation results.

2D thermal model of laser cladding process of Inconel 718

Abstract Layer by layer deposition in laser based metal additive manufacturing process causes accumulation of high thermal residual stresses. This may sometimes lead to dimensional inaccuracy and warping of the deposited clad layer. Additive manufacturing being expensive process, simulation may reduce the number of experimental trails. In the present work, 2D thermal model of Direct Metal Laser Deposition process taking Inconel 718 as deposited material was solved using the finite element software package COMSOL MULTIPHYSICS and the phase change of the material was incorporated. The thermal model is carried out for a 2D single clad bead to estimate HAZ and melt depth. The proposed 2D thermal model can predict the melt pool boundary at the interface of the clad layer and the substrate as a function of time for a given set of laser process parameters and found to be in good agreement with the experimental results.

Springback control in laser-assisted bending manufacturing process by using a fuzzy uncertain model

This study wants to propose a fuzzy model able to describe the inherent uncertainties related to a laser-assisted bending process and it is aimed at controlling of the springback phenomena, for a different set of laser process parameters. The process maps obtained are used to select the operational parameters in order to obtain the desired process output, providing as additional information how much the uncertainty of the model and the process varies by changing those operational parameters. The fuzzy model has also been used to assess the optimal parameters in order to satisfy the requirement of the least-cost.

Use of a carbon dioxide laser for environmentally beneficial generation of distressed/faded effects on indigo dyed denim fabric: Evaluation of colour change, fibre morphology, degradation and textile properties

Denim garments are particularly popular with the younger population of adults. Distressed or worn out effects have been and will continue to be popular with this market sector. These faded or worn effects have been achieved using a range of physical, chemical and mechanical finishes. Both wet and dry finishing of denim fabrics and garments pose severe environmental and health risks. Recently, environmentally beneficial decolourisation/ablation methods for denim fabrics have been investigated. Such methods have included plasma, laser, and ozone treatments. Researchers in this field have highlighted the potential of CO2 laser treatment of 100% cotton denim, however the textile performance post-treatment has not been properly investigated. In this study, light, medium and heavy weight indigo dyed 100% cotton denim fabrics were exposed to a CO2 laser at a range of power and intensity levels. Colour change was investigated using a Spectrophotometer, morphological structural analysis was carried using Scanning Electron Microscopy, and attenuated total reflectance Fourier transform Infrared spectroscopy (ATR-FTIR) was used to monitor the loss of indigo dye and degradation of the cellulose fibres. The thermal-oxidative degradation behaviour of fabrics was also studied using differential scanning calorimetry to obtain oxidation onset temperature. In addition, several fabric performance assessments were carried to evaluate tensile strength, colour fastness, air permeability and thickness. Findings reveal that the grayscale rating, which is the tone density and hence laser power affected the colour change and as the grayscale increased, the colour fading was higher and affected the fabric performance across all fabric weights. Based on this, the research recommends an optimum set of laser processing parameters to produce stressed or faded denim effects without compromising the fabric performance. This research demonstrates that faded effects on denim can be produced with low environmental and health risks.

A fuzzy logic-based model in laser-assisted bending springback control

The present investigation deals with the proposal of a fuzzy model able to describe the inherent uncertainties related to manufacturing processes and is applied to a laser-assisted bending process. The use of such a model is aimed at controlling of the springback phenomena, which occurs during the hybrid forming process, for different set of laser process parameters, i.e., initial deflection, laser power, laser scan speed, and number of passes. In particular, the uncertainties are propagated to the residual springback by the General Transformation Method, providing only an input-output relation. The fuzzy results are then compared with the measured data leading to the evaluation of the membership level of the dataset to the uncertain model. The process maps obtained are used to select operational parameters in order to obtain a desired process output, providing as additional information how much the uncertainty of the model and the process varies by changing those operational parameters. The large variability of the process is highlighted by the fuzzy model through large band of uncertainty that occur in all the process maps generated. The fuzzy model has also been used to assess the optimal parameters in order to satisfy the requirement of the least-cost. In this case, it resulted to be convenient reduce the number of passes and use the highest laser power.

Improved corrosion and wear resistance of Mg alloys via laser surface modification of Al on AZ31B

A highly intense laser beam from a continuous wave diode-pumped ytterbium laser source was used to synthesize a corrosion and wear resistant aluminum coating rich in Al 12Mg 17 intermetallic phase by direct melting of aluminum precursor powders on AZ31B Mg alloy substrates. The coating composition and microstructure were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high resolution energy diffraction spectroscopy in a transmission electron microscope. From X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy diffraction spectroscopy analysis it was confirmed that laser processing resulted in uniform distribution of a highly corrosion resistance Al 12Mg 17 intermetallic phase within the coating. The effect of this type of coating on the corrosion and wear resistance of the Mg alloy is investigated in the current study. Under the set of laser processing parameters employed in the current work, no significant change in microstructural and phase evolution and thereby corrosion and wear performance was observed for the laser processed samples. In general improved corrosion resistance was observed for the laser processed samples as compared to the untreated AZ31B. Also, as the precipitation of an intermetallic phase is expected to strain harden the matrix, an improvement in dry sliding wear was observed for the laser processed samples.

Process optimization of Ti–Nb alloy coatings on a Ti–6Al–4V plate using a fiber laser and blended elemental powders

A fiber laser was used to modify the surface composition of a Ti–6Al–4V plate through deposition of the blown powder mixture of Ti–45 wt.%Nb. Scanning electron microscopy and energy dispersive spectroscopy (EDS) were employed to examine the clad sections microstructure and chemical composition. The optimized set of laser processing parameters, including the laser power of 1100 W, the laser scan speed of 350 mm/min (or ∼5.83 mm/s), the laser spot diameter of 2 mm and the powder feed rate of 0.1 g/s was found with the identification of combined parameters, the laser specific energy, the powder density and the newly defined laser supplied energy (i.e. representing the amount of energy given to the unit mass of the blown powder). It is shown that, with these parameters, continuous beads can be formed with pore-free sections and a homogeneous composition corresponding to that of β (Ti, Nb) solid solution phase. Furthermore, Al and V elements are thoroughly replaced with a more biocompatible element, Nb, in the second layer of a Ti–Nb cladding build-up on the surface of the Ti–6Al–4V plate (i.e. after ∼1 mm in clad thickness from the clad/substrate interface).

Multilevel residual stress evaluation in laser surface modified alumina ceramic

The type and extent of residual stresses within laser surface modified alumina ceramic were investigated. Macro stresses were predicted with the help of the OOF2 simulation package, developed at the National Institute of Standards and Technology. The software utilizes a meshing technique to discretize the surface microstructure into a mesh suitable for finite-element analysis, which leads to stress determination. Micro stresses were estimated by the prediction of full width at half-maximum of the peaks from the X-ray diffraction patterns of processed samples. Under the present set of laser processing parameters, the ceramic was devoid of any major cracks, making it ideal for several applications. This study provides a tool for rapid evaluation and hence for controlling the stresses through tailoring the laser process parameters to suit a particular application.

Thermal and microstructural analysis for laser surface hardening of steel

The influence of parameters such as laser power, focusing conditions, and travel speed on the laser surface hardening of American Iron and Steel Institute 1045 steel has been investigated in terms of the microstructure and hardness of heat affected zones. Hardening trials were performed with a 500 W neodymium:yttrium aluminum garnet laser. Electron and optical microscopy were performed to correlate the hardness, hardness profiles, and microstructures that are achieved during laser surface hardening. A simple approach has been presented, which makes the Green’s functions application easier, to predict the temperature distribution during laser surface hardening. This approach can be used to predict the case depth, which can be achieved by using a given set of laser process parameters. The results obtained by using this approach compare well with the results obtained from a commercial finite element package, Engineering Analysis System.