Analysis of Shape Deformation from Densification of Additive Manufacturing Parts in Selective Laser Sintering

Additive Manufacturing (AM) has recently attracted huge attentions as a technology for the next generation of industry. Particularly for the manufacturing purposes, various aspects of AM are being studied and applied, such as prototypes for assembly tests, jig production, and actual parts manufacturing. Selective Laser Sintering (SLS) using polyamide is easy to apply to various industries, such as its superior mechanical properties and higher design freedom, but design that takes into account variation in dimensions after manufacture often leads to costly and time-consuming problems. As a way to reduce deformation in the production process, previous studies approached experimentally about the effects of thermal deformation or residual stress on deformation. This is difficult to apply to a specimen of various shapes and sizes and also has limitations as a common solution to dimensional inaccuracies. To propose a solution for mitigating shape deformation of AM part, this paper focused on the effect of phase change of material among various processing parameters that cause shape deformation and tries to present an analytic model. Modeling on the melting and sintering phenomena of powder was presented using Euler-Bernui beam equation. The proposed model was verified by measuring the density variation of manufactured AM components and analyzing the correlation between the degree of contraction and the energy density. Factors such as layer thickness, part thickness, and part placement height were identified to have significant effects on the actual deformation. It is also confirmed that dimensional accuracy of parts that show large deformation by bending has increased by 64.2% when a calibration model is applied through manufacturing of actual parts. Time and cost can be saved for industrial application of AM by applying this proposed calibration model. In addition, by using this model more efficiently in the CAD design process, dimensional accuracy can be enhanced.