Assessment of drilling characteristics of alumina coated on aluminium using CO2 laser

This paper reports experimental investigation of effect of laser parameters on the drilling responses of alumina coated aluminium substrates using 1.8 kW CO2 pulsed mode laser. Alumina was deposited on 4 mm thick Al 6065 plates by plasma spray technique. The main influencing factors were: Laser power on spatter deposition and Heat Affected Zone; Pulse frequency on entrance and exit circularities; Piercing time on taper, heat affected zone and exit circularity. Genetic algorithm optimization results indicated simultaneous improvement of 5.2% in hole quality at 416.6 W laser power, 1.4 kHz pulse frequency and 0.4 s piercing time. Response Surface Methodology indicated minimum spatter deposition area of 11.57 mm2, Heat Affected Zone 0.589 mm, taper 2.35° and maximum circularity at entrance 0.88 and exit 0.905 at 400 W laser power, 1.2 kHz frequency and 0.48 s piercing time. These results were in close agreement with those of Genetic algorithm. The optimum values were validated through confirmatory experiments.