Experimental And Simulation Study Of Pulsed Laser Milling On Ceramic Materials

Pulsed laser milling is a new technology of removing materials by using a series of densely overlapped laser pulses. In this paper laser milling technology was introduced to the process of machining ceramic, laser milling of ceramic materials was investigated from the experimental and numerical simulation. The main contents are as follows:According to laser milling principle, the milling model including depth, width, material removal rate, surface roughness and chip-removal were established for ceramic materials. A proper heat conduction equation was selected to calculate the power density threshold of laser milling and the conversion formula between overlapping rate and scanning speed was derived, the forming characteristics of laser milling were discussed.Laser milling experiment of Al₂O₃ ceramic sample was carried out by Nd:YAG pulsed laser. The crater dimension influenced by laser pulse width and defocused distance was investigated and proper scanning speed for good single-channel milling quality was chosen after overlapping rate experiment. The milling width and depth influenced by laser power, scanning speed and defocused distance was analyzed. After laser milling experiments, the milling width and depth of samples were measured and proper parameters were selected for milling large cavities.The orthogonal experiment was adopted to analyze the effects of process parameters, it can be found that laser power and scanning speed play more important role in milling depth and milling width. Form the measured surfac equality, it can be concluded that scanning speed and the scanning distance are important in improving milling quality. Based on the optimized parameters, multi-layers milling experiments were carried out and micro-structure was observed and the machining errors were discussed for the process of laser milling.A 3D FE model of the temperature field was established based on ANSYS software. The processing parameters such as laser power, scanning velocity, spot diameter and overlapping amount effecting on temperature field were analyzed. The milling depth and width calculated form numerical simulation was compared with experiment results and the agreements are obtained. The results indicate that the numerical simulation is valuable for predicting the milling depth and width of ceramic materials.