| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 99 === Compared with mechanical machining, laser machining is with the characteristics of non-contact, no residual chips, no cleaning needed, and more accurate. However, because nanosecond laser is a long pulse laser, it usually induces thermal effects which will deteriorates the machining accuracy and the material properties of the workpiece. Thus, it is very important to develop a method to minimize the influence of the thermal effect. In the research, the influence of processing parameters of nanosecond laser processing, laser power, and pulse energy on the machining performance and material properties was first explored. Subsequently, curve fitting method was applied to develop a method to obtain optimal processing parameters for deeper groove and minimized recast layer. Furthermore, the water-assisted method was added, and the results have shown that it can have 17 times machining depth than having laser processing in air. Besides, it also significantly decreases the thermal effect. By observing the morphology and topography of the machined workpiece, it was found that there was almost not a crater and a layered structure. The proposed method provides high surface quality, good accuracy, deeper depth, and good stability for nanosecond laser processing. It makes nanosecond laser processing more suitable for micro machining application with the advantages of low cost and use in simple surroundings.
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