Investigation Of Sub-surface Damage Of Silicon Carbide(SiC) Manufactured By Laser Machine And Ultra-precision Precision Grinding

Laser micromachining has excited vivid attention in various industrial engineering fields and in medicine, owing to the rapid progress in laser design. However, when irradiating the focused laser pulses to remove the material locally especially in a nanosecond laser, the machined surface, sub-surface and surroundings can be easily thermally damage by the plasma formation caused by excessive laser incidence. Such damages usually deteriorate the quality of laser machined surface. Research has identified that, operational reliability of machines? components depends on the manufacture/fabrication accuracy. Improving the surface and subsurface quality have been the most challenged issues in the laser machining fields.This experimental study is mainly about investigation of sub-surface damage of Silicon Carbide(Si C) micro- machined by Nanosecond pulse laser machine and precision grindingNanosecond laser has been known for good micro structuring fabrication process, its micromachining technology is one of the effective methods for precision processing of hard and brittle materials. It has been known for its unique advantages, especially for micromachining of hard materials such as Silicon carbide(Si C).However, subsurface damage induces into the work piece by its operation could be inevitable. In respect of this, the present study made investigation into the cause and the intensity of this damage and way to eliminate or reduce the damage effects to lowest level by applying precision grinding process.While machining Silicon Carbide(Si C), owing to its nature, micro crack occur on the machined subsurface. Due to this reasons, efficiency of the machining process is low. To sort out this problem, an experimental investigation of subsurface damage of Si C micro-machining by nanosecond pulse laser machine and precision grinding has been carried out in the present work to improve the machining performance while machining Sic.This experimental work presents an investigation into subsurface damage of Si C, machining by pulse laser machining and precession grinding. In this study, Silicon Carbide was micro-machined by Nanosecond pulse laser machining process. The influence of process parameters, i.e. laser power, scanning rate, assist gas pressure and repetition rate on the predominant machining criteria, i.e. the micro groove aspect ratio was studied. Determining the optimal processing parameter is routinely performed in engineering experimental process, as it has a direct and dramatic influence on product quality and costs. In this volatile and fiercely competitive market, traditional trial-anderror is no longer sufficient to meet the challenges of globalization. In view of this, practical use of Taguchi method in the optimization of processing parameters for laser machining has been adopted in this study. Taguchi method has been employed with great success in experimental designs for problems with multiple parameters due to its practicality and robustness.The settings of the process parameters used in this work were determined by using Taguchi?s experimental design method, with Taguchi method for design of experiment(DOE), other significant effects such as interaction among laser machining parameters are also investigated. Orthogonal arrays of Taguchi and the signal-to-noise(S/N) ratio are employed to find the optimal process parameter levels and to analyze the effect of the parameters on micro-groove crater aspect ratio. With the help of graphs, optimum parameter values were obtained and the confirmation experiments were carried out. The confirmation test experiment with the optimal levels of machining parameters was carried out in order to illustrate the effectiveness of the optimization method, after careful selection of optimized processing parameters; two sets of microgrooves were machined on Si C work piece by Nanosecond pulse laser machine.Confocal Microscope and Scanning electron microscopy(SEM) were used to analyze the kerfs? morphology and subsurface damages. The result has provided valuable insight into the laser machinability of silicon carbide. The subsurface damage of one of the machined work pieces was investigated immediately after the nanosecond pulse laser machining process, while the second work piece which was also machined by nanosecond pulse laser machine underwent post machined by precision grinding before subsurface damage investigation was carried out on it. The subsurface damage investigation have been carried out in order to ascertain the effects of nanosecond pulse laser machining on subsurface of Si C and to see how precision grinding can be used to eliminate or reduce the effects of any damage induce to Si C by Nanosecond pulse laser machining process. The results of subsurface investigation in this study have shown that precision grinding can reduce the intensity of subsurface damage induce to silicon carbide by nanosecond pulse laser machine.