Laser machining of alumina: Experimental and numerical approach for surface finish (original) (raw)
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International Journal of Applied Ceramic Technology, 2014
Laser machining technique has emerged as an innovative tool to effectively machine the structural ceramics, which previously was nearly impossible using various conventional machining techniques. However, obtaining a desired surface finish via laser machining is still a critical issue. As many physical phenomena act simultaneously during laser machining, it is very difficult to understand their influence in real time and predict the surface topography. To address this issue, a multiphysics-based finiteelement modeling approach was implemented to understand the influence of moving laser beam (with lateral overlap) on the generation of corresponding surface topography/profile/roughness during laser machining of structural alumina. A computation model that coupled heat transfer and computational fluid dynamics was designed to understand the combined influence of Marangoni convection, recoil pressure, cooling rates, and surface tension on the evolving surface topography during laser machining of structural alumina under various machining conditions. Both computational and experimental results evidently showed the systematic increase in surface roughness parameters with the increase in lateral overlap (0, 17, 33, 50, 67, and 83%). The results of the computational model are also validated by experimental observations with reasonably close agreement (AE3.5%).
Procedia Engineering, 2014
This paper deals with the machining of alumina ceramics by employing high intense laser source as pre-heating tool and machined at different cutting conditions to study the feasibility of laser-assisted machining (LAM) process. To understand the thermal response of the ceramics to laser heating, extensive heating studies were carried out to select the laser and machining parameters for LAM. The preliminary studies show that the work surface temperature mainly influenced by the laser power and scan speed.Based on the temperature results obtained from the heating studies the experimental conditions for LAM were selected. The LAM results were compared with conventional machining and presented in terms of cutting force, specific cutting energy and tool wear.It was observed that the increase in surface temperature above 850°Cresulted in reductionof cutting forcesand tool wear.
One-dimensional multipulse laser machining of structural alumina: evolution of surface topography
The International Journal of Advanced Manufacturing Technology, 2013
The development and understanding of laser-material interactions have steered to the machining of advanced structural ceramics. At one point, it was nearly impossible to machine effectively using various conventional machining techniques. Nevertheless, achieving a higher material removal rate along with a good surface finish is a critical issue. In this study, a multistep computational model based on COMSOL™ Multiphysics was designed and developed to study the influence of multiple laser pulses on the evolution of surface roughness of alumina. The computational model employed the various heat transfer and hydrodynamic boundary conditions and thermomechanical properties for better prediction of surface roughness under various laser processing conditions. The results indicate that, as the pulse rate increases, the surface roughness also increases. The results of the computational model are also validated by experimental observations with reasonably close agreement.
Computational predictions in single-dimensional laser machining of alumina
International Journal of Machine Tools & Manufacture, 2008
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.