Research On Basic Processing Technology Of K24 Alloy Micro-Holes Machined By Femtosecond Laser

Research on drilling of holes in Micro-scale has gained considerable attention in the present day manufacturing industries especially in the manufacturing of modern aircraft engine,which requires a number of film cooling holes to cool the hot end component actively.Due to high efficiency of Laser drilling,it is becoming a main processing method.The aim of this work is to analyze the basic principle of interaction of K24 super alloy with femtosecond laser and the processing Technology of its micro-hole machined by using femtosecond laser,hence the effects of laser parameters such as pulse width,pulse sequence,energy density,scanning velocity et al on the quality of the holes and the material ablation behavior were investigated.The surface morphology of drilling hole was analyzed using Scanning electron microscope(SEM).It was discovered that laser fluence has significant effect on optical penetration depth and heat penetration depth,so laser fluence is a significant parameter.The electron and the lattice temperature of the metal can be calculated from the interaction of laser beam and material using traditional double temperature model but it cannot describe the processing of complicated alloy machined by femtosecond laser in detail.Theory of the interaction of femtosecond laser with K24 Nickel based superalloy,was investigated using both simulation and processing experiment and through this right parameters were obtained.This research investigated three techniques of micro-drilling.The ablation threshold of K24 nickel based superalloy was analysis to obtain the threshold fluence of K24 Super alloy then single parameters experiments were carried out using each of the three techniques then the morphologies the of the hole surface and the wall cross sectional view of hole depth were obtained with the aid of scanning electron microscope.After the three techniques were investigated it was discovered that the most suitable method for the micro-drilling is helical drilling method.Therefore,orthogonal experiments of helical drilling was carried out to investigate the effects of parameters such as scanning speed,scanning number,repetition rates,pulse energies on surface quality,roundness of the hole and the taper to achieve the ultra-precision which is the aim of this research.