Parametric Analysis of the Selective Laser Sintering Process

Qualitative and quantitative analyses are required to develop Selective Laser Sintering into a viable Manufacturing process. A simplified mathematical model for sintering incorporating the heat tJ;ansfer equation. and the sintering rate equation, but using temperature independent thermal properties, is presented in this paper. A practical result is the calculation of sintering depthdeftned as the depth of powder where the void fraction is less than 0.1 as a function of control parameters, such as the laser power intensity, the laser scanning velocity, and the initial bedtemperature. We derive the general behavior of laser sintering. A comparison of model predictions with laser sinterlng tests is provided. Introduction The previous works on the Selective Laser Sintering have been concentrated on exploring suitable sintering materials and experimentally determining the control parameters. Little theoretical research has been done beyond Frenkel's sintering model [1]. However, a better model that predict the sintering behavior correctly could save a lot of experimental work. We here propose a simplified integrated model for Selective Laser Sintering which, through the verification of true sintering experiments, proved to be a valuable basis of the more sophisticated models to be developed in the future. It can also be used in the instructive parametric analysis of the sintering behavior. Treating the Selective Laser Sintering process as a system, the input variables are laser power and scanning rate. Output variables of this system should practically describe the quality of the sintered part.One important indication of part quality is its void fraction. Temperature acts as a intermediate state variable in this model. There are some other factors affecting the sintering process, such as the initial powder bed temperature, air flow condition, the optical, thermal and rheological properties of the powder, and the morphology of the powder. A conceptual model for selective laser sintering is thus derived as shown in Fig. 1. power ........._ .....o;;;r",... ... ....._-., degree of absorbed qAT sintering OPTICAL r-\ THERMAL SINTERING SUBMODEL L-....( SUBMODEL SUBMODEL laser jwer> laser scanning velocity environmental control parameters (temperature, air ..------...., Figure 1. The Integrated Model of Selective Laser Sintering