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Owing to the growing applications in medical equipment, the marine sector and automotive industries, laser transmission welding (LTW) is gaining increasing importance. LTW of two transparent acrylic thermoplastic materials, each of 4 mm thickness, was demonstrated using a diode laserpumped solid-state Nd:YVO4 pulsed laser. The effect of process parameters such as laser power, pulse frequency and scanning speed have been investigated and a multi-objective optimization based on desirability function technique was used for the betterment of the results. A validation test has been performed which shows that the predicted results are compatible with actual value. Scanning speed was found to be the process parameter that mostly affects the weld strength. A scanning electron microscope (SEM) was used to study the morphology of the weld zone. It was observed from SEM micrographs that the heating zone in the weld area often generates bubbles and ablation which enhance the joining strength. [ABSTRACT FROM AUTHOR]

In the present day situation higher efficiency, better beam quality, reliability and ease of beam delivery through optical fiber have given diode pump fiber laser a potential to perform in a better way than the traditionally used CO2 or Nd:YAG laser in sheet metal cutting operation. Change in focal distance in the downward direction from the top surface in a controlled manner, eliminates the problem of proper focusability which leads to the formation of uniform melt pool throughout the machining period and results in formation of kerf with high aspect ratio. Investigation of the influence of cutting angle and constant z-height movement with other process parameters like cutting speed, pulse frequency, duty cycle and average power related to the kerf deviation and surface roughness of the 1 mm thick 316L stainless steel sheet has been done. Evaluation of the parametric dependent factors of the cut quality has been made by the implementation of response surface methodology (RSM) with the help of design of experiments (DOE). The optimum parametric settings relating to different machining conditions have also been evaluated. [ABSTRACT FROM AUTHOR]

The current research elaborates an experimental study on poly (methyl methacrylate) (PMMA), to produce microchannels using the laser transmission cutting technique, utilizing a nanosecond pulsed Nd:YAG laser system. The cutting operation was carried out in partially submerged condition. The prime objective during the machining operation was to minimize the heat affected zone (HAZ) and kerf width. Lamp current, pulse frequency, pulse width and cutting speed were the process parameters under consideration during the experimentation. The developed microchannels characteristics such as HAZ and kerf width were subsequently measured and analysed. Response surface methodology (RSM) technique was applied to develop the mathematical relationships between the input process parameters and output responses. Model adequacy was tested using the method of analysis of variance (ANOVA). The optimal combinations of process parameter settings were obtained through single and multi-objective optimizations methods. [ABSTRACT FROM AUTHOR]

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, 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]

This study investigates the effect of five parameters on circularity and taper of drilled holes in pulsed Nd:YAG laser microdrilling process. The effect of various process parameters like lamp current, pulse frequency, pulse width, air pressure, and focal length of Nd:YAG laser microdrilling on hole circularity at entry, exit, and taper has been investigated through response surface methodology (RSM)-based experimental study. The significant parameters have been selected based on the analysis of variance (ANOVA). The parametric combination for optimal hole circularity and hole taper has also been evaluated. In micromanufacturing, circularity of a drilled hole at entry, exit, and taper are important attributes which greatly influence the quality of a drilled hole. The drilling operation has been carried out on titanium nitride-alumina (TiN-Al2O3) composite, an important electroconductive ceramic suitable for wear and heating applications. [ABSTRACT FROM AUTHOR]