•The 3D mathematical model of the laser cutting of current collectors is developed.•Penetration time, depth, width, and absorptivity, are analyzed with selected laser parameters.•Melt pool flow, melt ...pool geometry and temperature distribution are investigated.•The transition from partial to full penetration modes and crest are observed for copper.•Not only the crest, but also two deep penetration holes are observed for aluminum.
One of the challenges of the lithium-ion battery manufacturing process is the sizing of electrodes with good cut surface quality. Poor cut surface quality results in internal short circuits in the cells and significant heat generation. One of the solutions that may improve the cut quality with a high cutting speed is laser cutting due to its high energy concentration, fast processing time, high precision, small heat affected zone, flexible range of laser power and contact free process. In order to utilize the advantages of laser electrode cutting, understanding the physical phenomena for each material is crucial. Thus, this study focuses on the laser cutting of current collectors, such as pure copper and aluminum. A 3D self-consistent mathematical model for the laser cutting, including fluid flow, heat transfer, recoil pressure, multiple reflections, capillary and thermo-capillary forces, and phase changes, is presented and solved numerically. Simulation results for the laser cutting are analyzed in terms of penetration time, depth, width, and absorptivity, based on these selected laser parameters. In addition, melt pool flow, melt pool geometry and temperature distribution are investigated.
Laser cutting of nickel-based superalloy sheets, having wide applications in aircraft and rocket industries, is important from the quality of cut point of view. Keeping this in view, a hybrid ...approach of Taguchi method (TM) and principal component analysis (PCA) has been applied for multi-objective optimization (MOO) of pulsed Nd:YAG laser beam cutting (LBC) of nickel-based superalloy (SUPERNI 718) sheet to achieve better cut qualities within existing resources. The three-quality characteristics kerf width, kerf deviation (along the length of cut), and kerf taper have been considered for simultaneous optimization. The input parameters considered are assist gas pressure, pulse width, pulse frequency, and cutting speed. Initially, single-objective optimization has been performed using TM and then the signal-to-noise (S/N) ratios obtained from TM have been further used in PCA for multi-objective optimization. The results of MOO include the prediction of optimum input parameter level and their relative significance on multiple quality characteristics (MQC). The responses at predicted optimum parameter level are in good agreement with the results of confirmation experiments conducted for verification tests.
Compliant mechanism transfers motion or force using the elastic deflection of flexures or the whole mechanism (distributed). Pantograph is a widely proven mechanism which can imitate motion. The ...compliant pantograph models proposed by earlier researcher are limited to use of all circular flexure hinges; with some reporting geometric amplification (GA) around 2. Thus the present research work is an attempt towards using different combinations of flexures viz. circular, elliptical and parabolic deployed (for proposed six models), while developing the compliant pantograph (CP) in order to improve the GA. Also the effect of material Stainless Steel (SS) and Mild Steel (MS) on the performance of CP is presented. The finite element analysis is undertaken and output displacement is estimated for pre-decided range of input motion The maximum GA achieved for one of the combinations (combination no. 4) using SS is 2.57 wherein the flexures considered consist of two Elliptical and four circular flexures. Depending on desirable output range any of the above models can be used in micro stages/slides and many more precision applications.
•A diode laser with an output power of 2 kW based on the multi-wavelength multiplexing is introduced.•A theoretical laser cutting model is built to predict the cutting performance of a direct diode ...laser source.•The cutting result of the diode laser is better than that of the fiber laser when the thickness of sheet is more than 3 mm.
In this paper, a theoretical laser cutting model based on absorption calculations and the characteristics of multi-wavelength laser beam is introduced to predict the cutting performance of a direct diode laser source (2 kW output power from an optical fiber with a 105 μm core diameter and a numerical aperture of 0.2). Cutting experiments are performed on stainless steel sheets (304) with thicknesses ranging from 1 mm to 10 mm. When comparing with the relevant industrial cutting results using fiber lasers, this diode laser source can obtain a greater speed at the thickness of samples above 3 mm. The experimental results have a good agreement with the theoretically predicted results and demonstrate the cutting ability of the diode laser source of such power class and brightness class for use in industrial laser cutting applications.
The results of an experimental investigation on the physical and chemical characteristics of cement-based materials under laser interactions are presented. The laser cutting tests were conducted ...using a multi-mode continuous fiber laser with a laser power of 1 kW. The experimental variables were laser speed, water to cement ratio, and material compositions including cement paste, cement mortar, and ultra high-performance concrete (UHPC). In order to evaluate the mass removal mechanisms of cement-based materials under laser interactions, the effect of laser cutting was evaluated in terms of kerf width, penetration depth, and chemical composition changes before and after the interaction with laser using EDX analysis. The test results reveal that adding silica sand in cement-based materials leads to decreasing penetration depth and increasing kerf width. Unlike the cement paste and cement mortar series, UHPC specimens showed no discernible crack observed by the naked eye after laser interaction due to its high strength. Furthermore, the chemical analysis indicates that chemical composition changes were caused by various mechanisms including dehydration of calcium hydroxide and thermal decomposition of calcium carbonate.
The effectiveness of finite element simulation techniques for laser cutting of 1.2-mm-thick aluminium sheets has been studied. Lagrangian and Arbitrary Lagrangian-Eulerian techniques were used to ...model and simulate laser cutting process. The reliability of finite element results were evaluated by general energy balance analysis and experimental results. Temperature and stress distribution along with heat-affected zone were predicted during the laser-induced process in line with experimental conditions under ABAQUS finite element code. Heat transfer analysis relying on thermal loading was employed to reach the best efficiency. By using field-emission scanning electron microscope, morphological, structural, and elemental changes in the cutting sections were analyzed along with the X-ray diffraction technique. Obtained stress and heat-affected zone are highly dependent on the element type as well as numerical method. Both numerical method, ALE and Lagrangian, are compared to each other in terms of power absorption, cut surface morphology, and cutting efficiency. The results show that ALE method is in good agreement with experimental data.
Laser cutting has started to be used as an effective method for cutting out blanks from rolled sheet metals because of its high flexibility for cutting lines and high productivity. However, residual ...stresses, which are generated by laser cutting, have been the greatest obstacle for the popularization of laser cutting. One of the problems is the warp which appears in the sheet metal after being subjected to bending processes after laser cutting. The authors present a light press method for reducing residual stress generated by laser cutting. The method is to give a light press on the sheet metal edge and to reduce tensile residual stress generated near the laser cutting surface. In particular, this present paper especially focuses upon optimization of working conditions depending on mechanical properties of the blank and the effect of the heat affected zone in laser cutting. Experiments of U-bending after applying light press were conducted for usability of this method. The FEM analyses were carried out in order to investigate proper working conditions depending on various mechanical properties. As a result, the optimum press pressure of the light press method for various mechanical properties was found out for reducing residual stress which caused by laser cutting, by taking warp after U-bending as an evaluation parameter. The relationship between the optimum pressure and the proof stress was quantitatively and specifically clarified for several sets of mechanical properties. It was also found that the influence of heat-affected-zone area and intensity of residual stress by laser cutting on the optimum press pressure was small.
•Laser circular cutting results in asperity free cutting sites.•Carbonization is observed at the rear side of holes due to combustion.•Temperature remains high along cutting edges of large diameter ...hole.•von Mises stress is higher at top circumference of hole edges.
A Kevlar laminate has negative thermal expansion coefficient, which makes it difficult to machine at room temperaures using the conventional cutting tools. Contararily, laser machining of a Kevlar laminate provides advantages over the conventional methods because of the non-mechanical contact between the cutting tool and the workpiece. In the present study, laser circular cutting of Kevlar laminate is considered. The experiment is carried out to examine and evaluate the cutting sections. Temperature and stress fields formed in the cutting section are simulated in line with the experimental study. The influence of hole diameters on temperature and stress fields are investigated incorporating two different hole diameters. It is found that the Kevlar laminate cutting section is free from large size asperities such as large scale sideways burnings and attachemnt of charred residues. The maximum temperature along the cutting circumference remains higher for the large diameter hole than that of the small diameter hole. Temperature decay is sharp around the cutting section in the region where the cutting terminates. This, in turn, results in high temperature gradients and the thermal strain in the cutting region. von Mises stress remains high in the region where temperature gradients are high. von Mises stress follows similar to the trend of temperature decay around the cutting edges.
The effect of laser cutting on the microstructure and microhardness of the cutting surface of gears from a gear train made of structural St3 carbon steel is investigated. The structure in the ...laser-affected zone is found to differ from the initial ferritic–pearlitic structure and to consist of several layers with a total thickness of about 0.35 mm. The microhardness of this zone can be 420–500 HV, which is 2.5–3 times higher than the initial hardness of the steel. The possibility of combining laser cutting of rolled products of a given thickness with surface hardening is confirmed.
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