• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1389-1393
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• 2007

Selective Laser Sintering (SLS) is currently recognized as a leading process in the new field of solid freeform fabrication (SFF). It is used to fabricate in a short time any 3 dimensional shapes by layer-by-layer sintering of polymer, ceramic or metal powder. To develop this SFF system, it needs effective laser scanning path, temperature and z-axis control for lamination. Therefore, in this study, through the application of control algorithm for sintering process have performed, temperature evaluation for sintering process has performed and the manufacturing sample using SLS process.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.518-519
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• 2006

A connection between pulse-periodical laser radiation power and stability of liquid-metal contacts between powder particles during selective laser sintering (SLS) is determined based on analysis solving the problem of stability of liquid column in the gravity and capillary forces field. On the grounds of obtained relationships the optimization of pulse-periodical laser radiation power and SLS-process duration is realized, that allows to produce voluminous powder porous materials with pre-determined physical and mechanical properties and surface geometry. Results of metallographic investigations of powder porous materials of titanium powder produced with technological regimes calculated by means of obtained relationships are given in the work

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.516-524
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• 2012

Selective Laser Sintering(SLS) system consists of various element technologies. Main components of the system include a position control system, a speed control system of the roller, and nitrogen atmosphere furtherance for the powdered sintering. Other systems which make the core of the SLS system are build room and the feed room for powder epitaxial, a temperature control system, and a scan path generator for the laser. The powder material for laser sintering is necessary to produce prototypes in Solid Freeform Fabrication(SFF) based on SLS process. This powder material is sintered in powder room using $CO_2$ laser after spreading evenly using roller to reproduce mold via SFF. This study addresses an SFF system by using the SLS process which applies single laser system to enable manufacturing of 3D shape. And to evaluate applicability of the single laser system, experiments were conducted with optimal fabricating process.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1404-1409
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• 2007

Polymers for laser sintering were needed in order to fabricate the articles with the three-dimensional duplication equipment of SLS (selective laser sintering) process. The thermal properties, particle size, distribution, and shape of polymer powder had a close relation with the processibility of laser sintering. In this study, we prepared new polymer powders with uniform size and higher bulk density by wet process. Wet process consists of several finely-controlled steps such as dissolution, nucleation, propagation and crystallization. Several additives were added to improve the thermal, rheological, and flow properties.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.193-194
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• 2006

A solid freeform fabrication (SFF) system using selective laser sintering (SLS) is currently recognized as a leading process and SLS extends the applications to machinery and automobiles due to the variousmaterials employed. In order to develop a more elaborate and rapid system for fabricating large objects compared to existing SLS, this study employs a new selective dual-laser sintering (SDLS) process. Also, this paper will address development of an SFF system which employs the dual laser system and the unique scanning device. 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 powder.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.282-285
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• 2009

Selective laser sintering (SLS) is a fast growing process of rapid production fur metallic based parts. To restore damaged mold surface using SLS, single layer experiments of $20{\mu}m$ Fe-Cr powder was performed under various heat input. Process window of $20{\mu}m$ Fe-Cr powder provided feasible process parameters for the smooth regular surface. To estimate coherence between melted powder and basematal, tendency of hardness distribution has been observed. Hardness of melted zone and remelted zone was diversified from 5GPa to 6.5GPa. It is over 2 times compared of hardness of basemetal. Average surface roughness of each direction on surface of melted powder was measured. Experimental results show that the mold restoring process using SLS can be successfully applied in the mold repair industry.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.278-281
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• 2009

Selective laser sintering(SLS), a kind of rapid prototyping technology, can provide a process to form many types of coatings. Coated layers by selective laser melting are highly influenced by substrate, powder and laser parameters such as laser power, scan rate, fill spacing and layer thickness. Therefore an attempt to fabricate Fe-Ni-Cr coating on AISI H13 tool steel has been performed by selective laser sintering. In this study, Fe-Ni-Cr coating was produced by experimental facilities consisting of a 200W fiber laser which can be focused to 0.08mm and atmospheric chamber which can control atmospheric pressure with Ar. With power increase or energy density decrease, line width was decreased and line surface quality was improved with energy density increase. Surface quality of coating layer was improved with fill spacing optimization or layer thickness decrease.

• Korean Journal of Metals and Materials
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• v.50 no.3
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• pp.191-200
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• 2012

The purpose of this paper is to review the state of laser processing technology using metal powders. In recent years, a series of research and development efforts have been undertaken worldwide to develop laser processing technologies to fabricate metal-based parts. Layered manufacturing by the laser melting process is gaining ground for use in manufacturing rapid prototypes (RP), tools (RT) and functional end products. Selective laser sintering / melting (SLS/SLM) is one of the most rapidly growing rapid prototyping techniques. This is mainly due to the processes's suitability for almost any materials, including polymers, metals, ceramics and many types of composites. The interaction between the laser beam and the powder material used in the laser melting process is one of the dominant phenomena defining feasibility and quality. In the case of SLS, the powder is not fully melted during laser scanning, therefore the SLS-processed parts are not fully dense and have relatively low strength. To overcome this disadvantage, SLM and laser cladding (LC) processes have been used to enable full melting of the powder. Further studies on the laser processing technology will be continued due to the many potential applications that the technology offers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.221-222
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• 2007

• Journal of Powder Materials
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• v.30 no.1
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• pp.7-12
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• 2023

Metal-additive manufacturing techniques, such as selective laser sintering (SLS), are increasingly utilized for new biomaterials, such as cobalt-chrome (Co-Cr). In this study, Co-Cr gas-atomized powders are used as charge materials for the SLS process. The aim is to understand the consolidation of Co-Cr alloy powder and characterization of samples sintered using SLS under various conditions. The results clearly suggest that besides the matrix phase, the second phase, which is attributed to pores and oxidation particles, is observed in the sintered specimens. The as-built samples exhibit completely different microstructural features compared with the casting or wrought products reported in the literature. The microstructure reveals melt pools, which represent the characteristics of the scanning direction, in particular, or of the SLS conditions, in general. It also exposes extremely fine grain sizes inside the melt pools, resulting in an enhancement in the hardness of the as-built products. Thus, the hardness values of the samples prepared by SLS under all parameter conditions used in this study are evidently higher than those of the casting products.