Computational predictions in single-dimensional laser machining of alumina

Machining of alumina was investigated in this study by using a JK 701 pulsed Nd:YAG laser. A hydrodynamic machining model was developed which incorporated the effect of multiple reflections on the amount of laser energy absorbed, the thermal effects for melting the material, vapor pressure effect for expelling out the molten material, material losses due to evaporation and the inverse effect of surface tension on the expelled depth .The model also incorporated the transient effect of laser beam de-focusing due to change in machined depth as a function of expelled material during machining for precise estimation of the melted depth during each pulse. It was observed that the material removal was a combination of melt expulsion and evaporation processes. The developed model would be an excellent tool for advance prediction of the total thermal energy and time required for removal and/or machining of desired depth of material.