Chung-Hwan Kim

Design and Evaluation of Digital Mirror System for SLS process

Selective laser sintering (SLS) is currently recognized as a leading process in the new field of solid freeform fabrication (SFF). In order to develop more elaborate and speedy system for fabricating large objects compared to existing SLS, this study employs digital mirror system (DMS) for selective laser sintering (SLS) process. DMS contains 3-axis dynamic focusing lens, zoom beam expander, x-y galvano mirror, reflection mirrors for scanning large area instead of the existing fthetas lens used in commercial SLS. Also, in the SLS, the sintering temperature, laser beam power and layer thickness have a great influence on sintering of the polymer. Experiments were performed to evaluate the effect of a scanning path and fabrication parameters on sintering process and to fabricate the various 3D objects using polymer

Development of polyamide-6 powders and its effect on the fabrication by selective laser sintering

In the solid freeform fabrication (SFF) system using selective laser sintering (SLS), polyamide-12 powder is currently recognized as general materials. Polyamide-12 powder has properties as average particle size is 58µm, density is 0.59 g/cm3. The object of this study is obtained base data that some kinds of polyamide-6 powders with different shape and particle size were fabricated to investigate the formability, microstructure and mechanical properties. Especially, the particle shape distribution played an important role in the precision of fabrication. To make similar type particle size and particle shape of polyamide-12 powder, polyamide-6 powder’s particle pulverize that until it under 100um using the process of dry type low temperature. Also, polyamide-6 powders having the average size of under 100um were treated thermally in order to keep the spherical symmetry shape. And to develop a more elaborate and rapid system, this study employs a new SLS device with a 3-axis dynamic focusing scanner system instead of the existing fθ lens used in commercial SLS. Based on materials and device, experiment performed to about various sintering condition such as build room temperature, feed room temperature, scan speed, scan spacing, laser power and layer thickness.In the solid freeform fabrication (SFF) system using selective laser sintering (SLS), polyamide-12 powder is currently recognized as general materials. Polyamide-12 powder has properties as average particle size is 58µm, density is 0.59 g/cm3. The object of this study is obtained base data that some kinds of polyamide-6 powders with different shape and particle size were fabricated to investigate the formability, microstructure and mechanical properties. Especially, the particle shape distribution played an important role in the precision of fabrication. To make similar type particle size and particle shape of polyamide-12 powder, polyamide-6 powder’s particle pulverize that until it under 100um using the process of dry type low temperature. Also, polyamide-6 powders having the average size of under 100um were treated thermally in order to keep the spherical symmetry shape. And to develop a more elaborate and rapid system, this study employs a new SLS device with a 3-axis dynamic focusing scanner system i...