Investigation of the effect of processing parameters for hole quality in laser drilling

Laser is used for cutting, drilling, welding etc. in industry. Today, mostly CO2 and Nd:YAG lasers are used in industrial means. Laser machines are rapid, no contacting with materials and they can be worked without producing crust. Besides, those machines have disadvantages like material crooking and burning caused by high temperature and their high settling costs. In this study, CO2 laser machine is used for drilling processes. Processing parameters are selected as 1.2-4 mm working piece thickness, 2500-4000 W laser output power, (-4)-(-2) laser focus setting, 8-14 bar assisted gas pressure and 500-1200 Hz laser frequency. After the drilling process, by making the measurements of diameter, Heat affected zone and resolidification material size on the pictures taken with optic microscope, the effect of processing parameters on hole quality is investigated. For 1,2 mm thickness, on the upper and lower surfaces, hole of 2500 W, 0 inç, 10 bar, 500 Hz is obtained as the nearest circle with diameter of 0,98 mm. For 2 mm thickness, on the upper and lower surfaces, hole of 2500 W, -4 inç, 8 bar 800 Hz is obtained as the nearest circle with diameter of 0,66 mm. For 2,5 mm thickness, on the upper and lower vii surfaces, hole of 3000 W, -4 inç, 8 bar, 1200 Hz is obtained as the nearest circle with diameter of 0,58 mm. For 4 mm thickness, on the upper and lower surfaces, hole of 3000 W, -4 inç, 12 bar, 1000 Hz is obtained as the nearest circle with diameter of 0,86 mm. And hole of 2500 W -2 inç, 8 bar, 1200 Hz _1 has the minimum resolidification area of 0,03 mm and heat affected zone of 0,18 mm. The parameters of hole 2500 W -2 inç, 8 bar, 1200 Hz are the most regular ones in the aspect of hole taper angle and inlet cone angle for 2 mm thickness.