Experimental study about micro hole processing by picosecond laser

In order to solve the problem of low quality of micro hole processed by micro/nanosecond laser, using pulse laser with pulse width of 200ps and high speed rotary cutting method, a micropore process test with a diameter of 200μm was conducted on SUS 304 stainless steel sheet with thickness of 0.2mm. The morphologies of the micro holes were observed by laser scanning confocal microscope. The effects of cutting speed, laser power and defocusing distance on machining quality of aperture, taper and heat affected zone were investigated. The results show that, the cutting speed has the direct influence on the quality of micro porous wall. By increasing the rotating speed, the overlap rate of laser pulse and the heat affected zone of the inner wall of micro hole can be reduced. At the same time, the machining quality of micro incision by rotary cutting method can be improved by increasing laser power. The taper of micro hole can be reduced to a certain extent by adopting positive defocusing machining. The study shows that, the optimized technological parameters can be used to process small taper pores with small heat affected zone and good edge quality.