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Laser beam cutting of Inconel 625 superalloy with a Nd:YAG laser in a submerged condition has been studied here. The effect of the underwater laser beam cutting parameters such as lamp current, pulse frequency, pulse width, cutting speed, height of water column on Kerf width and depth of cut are investigated using response surface methodology (RSM). The developed mathematical models are tested by analysis of variance (ANOVA) method to check their adequacy. The central composite design (CCD) technique based on RSM is employed here to carry out the experiments to achieve optimum responses with a reduced number of experiments. From the ANOVA analysis it is found that pulse frequency is the most dominant factor. Height of water column has great impact on quality characteristics of the cut zone. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an experimental investigation on diode laser transmission welding of dissimilar thermoplastics between PMMA (polymethyl methacrylate) and ABS (acrylonitrile butadiene styrene) has been carried out. The effect of the laser welding parameters such as laser power, welding speed, stand-off distance and clamp pressure on weld strength and weld width is investigated using response surface methodology (RSM). Planned experiments and subsequent analyses are carried out to develop the mathematical models to establish the correlation between the process parameters and the responses. The adequacy of the developed models is tested using the sequential F-test, lack-of-fit test and the analysis-of-variance (ANOVA) technique. A numerical multi-objective simultaneous optimization technique, in which the RSM is incorporated, is used to find the optimum solutions, according to the desired optimization criteria. In addition to that, a graphical optimization technique is, also implemented which allow identifying a region in the graphic where optimal conditions lay on. [Copyright &y& Elsevier]

Abstract: In this research, a systematic investigation on laser transmission contour welding process is carried out using finite element analysis (FEA) and design of experiments (DoE) techniques. First of all, a three-dimensional thermal model is developed to simulate the laser transmission contour welding process with a moving heat source. The commercial finite element code ANSYS® multi-physics is used to obtain the numerical results by implementing a volumetric Gaussian heat source, and combined convection–radiation boundary conditions. Design of experiments together with regression analysis is then employed to plan the experiments and to develop mathematical models based on simulation results. Four key process parameters, namely power, welding speed, beam diameter, and carbon black content in absorbing polymer, are considered as independent variables, while maximum temperature at weld interface, weld width, and weld depths in transparent and absorbing polymers are considered as dependent variables. Sensitivity analysis is performed to determine how different values of an independent variable affect a particular dependent variable. [Copyright &y& Elsevier]

Abstract: In this paper, simultaneous laser transmission welding process is systematically investigated via process modeling, using an FEM and RSM combined approach. The objective of the present research is to study the effects of process parameters on the temperature field and weld bead dimensions. The thermal field is simulated by solving a three dimensional transient heat diffusion equation with temperature dependent material properties using the ANSYS® multi-physics. Response surface methodology is then applied for developing mathematical models based on simulation results. The second order equations developed by RSM can predict the values of the responses with significant accuracy. The effect of parameters and their interactions on the responses are studied using the developed response surface models. The mathematical models are further used in search of the optimal process window for obtaining an acceptable weld. The graphical optimization results into a couple of overlay contours plots, which allow quick visual inspection of the area of feasible response values in the factor space to choose the favorable welding parameter combination. [Copyright &y& Elsevier]

Abstract: The influence of the carbon black on temperature distribution and weld profile, during laser transmission welding of polymers, is investigated in the present research work. A transient numerical model, based on conduction mode heat transfer, is developed to analyze the process. The heat input to the model is considered to be the volumetric Gaussian heat source. The computation of temperature field during welding is carried out for polycarbonates having different proportion of carbon black in polymer matrix. The temperature dependent material properties of polycarbonate are taken into account for modeling. The finite element code ANSYS® is employed to obtain the numerical results. The numerically computed results of weld pool dimensions are compared with the experimental results. The comparison shows a fair agreement between them, which gives confidence to use the developed model for intended investigation with acceptable accuracy. The results obtained have revealed that the carbon black has considerable influence on the temperature field distribution and the formation of the weld pool geometry. [Copyright &y& Elsevier]