Research On Experimental System And Technique Of Femtosecond Laser Micromachining

Silicon carbide(SiC) ceramic shows abroad application background in the feld ofmicro mold manufacturing due to its exceptional properties. Although grinding is themost effective method for ultra-hard material precision machining at present, there aresome problems such as easily wearing of grinding wheel and difficulty in machining theinner pointed angle of composed faces. Resin-based carbon fiber composite material iswidely used in the aerospace field. There are burrs, delamination heat effect and otherproblems existing in current cutting method of this material. For the above issues, baseon femtosecond laser, this paper presents the machining technology of SiC micro-structure aiming to reduce grinding wheel wear as rough machining before grinding,and shows the potential of cutting of resin-based carbon fiber composite material.In this paper, femtosecond laser micromachining system composed of femtosecondlaser, optical transmission device, three-axis stage and assistant device was set up;method of adjusting the focus position was designed; and controlling software wasdeveloped in the VC++environment.The impacts of scanning velocity(v) and pulse energy(P) on ablation of SiC werediscussed and optimized parameters were acquired to machine3D micro-structures.3Dmicro-structures were machined respectively through the methods of lens focusing andmicroobjective focusing. Experimental results show that, the optimum parameters arearound at v=1mm/s，P=10μJ in both focusing method, and microobjective focusingmethod can obtain higher surface figure accuracy but lower processing efficiency,which is appropriate for3D micro-structures of smaller size and higher processingefficiency while lens focusing methods is suitable for the contrary ones. The resultsdemonstrate that it is feasible to machine ultra-hard material micro-structures withfemtosecond laser before grinding as rough machining.Samples of resin-based carbon fiber composite material were respectively cutthrough line-by-line and layer-by-layer scanning, the impacts of scanning velocity andpulse energy on cutting results were studied. Experimental results indicate that layer-by-layer scanning is the appropriate method; of which the kerf width is about0.6mm; themaximum knifing of2.5mm and kerf verticality of7.5°inclination are acquired at320mW,1mm/s; knifing is influenced more significant by laser power, and can increaseby adding the lines number in each layer. No burr or gap forms; the cutting surface issmooth and homogeneous with oxidation and carbon fiber exposed only on the kerfbottom surface, and the surface roughness is around1μm to1.5μm.