Experimental Study On Pulsed Laser Micro-drilling Of Cu₅₀Zr₅₀ Amorphous Alloy

With the development of miniature and precise modern industrial products,the demand of tiny holes of which the diameter is less than 1mm has been increasing during the manufacturing process.Compared with traditional machining methods,the rapid processing can be achieved by the laser micro technology.For different material and structural tiny holes,it can be fabricated by this technology.By connecting with CNC machine tools,a variety of processing systems can be constituted so that drilling,cutting,welding and heat treatment processes can be completed by one machine.The machanism of laser drilling is analyzed in detail,based on certain theoretical analysis,the precision hole with a smaller diameter is made on the 80 um thick Cu₅₀Zr₅₀ amorphous foil.Through adjusting the process parameters,such as power,pulse width and the defocus amount of the laser welding machine,the craft technology of laser drilling is studied and effeets of parameters including laser power,pulse width and defocus craft on drilling quality are analyzed during laser drilling.According to the analysis and research of experimental results,it is found finally that:The out put power of the laser has a directeffect on the size of the hole.When the laser power changes from 60 W to 180 W,the pore size is increased,but the quality of the hole is poor.The quality of the holeis influenced by pulse width.The aperture is also increased when the pulse width varied from 0.5 ms to 1.7ms.With the decrease of pulse width,the diameter of holesis decreased,and meanwhile the surface roughness and the size accuracy of holesis reduced.Defocus has a significant impact on the shape of holes.When defocus amount changes from-1mm to +1mm,the pore size shows different variation at 60 W,70W,80 W and 90 W laser power.Moreover,The change trend of pore size under different out of defocus is related to the laser power.With the increase laser pulse width and laser power,the heat affected zone is obviously increased.This is because that the laser pulse width and laser power increase the laser energy density.The material around drill holes absorbs more heat leading to the increase of heat affected area.When the laser energy is constant value,the change of defocus amount can result in the fluctuation of the heat affected zone.Furthermore,the fluctuation is greater in the positive defocus amount and it is smaller in the negative amount.