Method and apparatus for producing parts by selective sintering

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder dispensing mechanism includes a drum which is moved horizontally across the target area and counter-rotated to smooth and distribute the powder in an even layer across the target area. A downdraft system provides controlled temperature air flow through the target area to moderate powder temperature during sintering.Board of Regents, University of Texas Syste

Method for producing parts by selective sintering

A method and apparatus for selectively sintering a layer of powder to produce a part as a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder dispensing mechanism includes a drum which is moved horizontally across the target area and counter-rotated to smooth and distribute the powder in an even layer across the target area. A downdraft system provides controlled temperature air flow through the target area to moderate powder temperature during sintering.Board of Regents, University of Texas Syste

Selective Laser Sintering Part Strength as a Function of Andrew Number, Scan Rate and Spot Size

Selective Laser Sintering has been modeled analytically and numerically, and studied experimentally. Further investigation is necessary to couple the results of modeling with experimental data. At Clemson University, numerical modeling of heat transfer phenomena is used to predict temperatures within the powder layer as a function of process parameters. Efforts are focused on delivering process speed up through improved process understanding. Initial modeling results and current understanding of the effects of process parameters on the strength properties offreeform parts produced by the SLS process are presented.Mechanical Engineerin

On dimensional stabilities: Modeling of the Bonus-Z during the SLS Process

This work is a first step towards the prediction of the dimensions and thermomechanical properties ofparts made with the Selective Laser Sintering (SLS) technology. An important variation of the dimensions is found in the Z-direction of the build. This phenomenon is known as the "Bonus-Z" where material properties differ from those in the rest of the part due to a non-homogeneous sintering. The focus of this work is the characterization and the modeling of the bonus-Z phenomenon, by relating it to the energy input. The polymer powder used in this study is polycarbonate.Mechanical Engineerin

Multiple material systems for selective beam sintering

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder comprises a plurality of materials having different dissociation or bonding temperatures. The powder preferably comprises blended or coated materials.Board of Regents, University of Texas Syste

Method and apparatus for producing parts by selective sintering

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. The powder can comprise either plastic, metal, ceramic, or polymer substance. In the preferred embodiment, the aim of the laser is directed in a continuous raster scan and the laser turned on when the beam is aimed with the boundaries of the particular cross-section being formed.Board of Regents, University of Texas Syste

Method and apparatus for producing parts by selective sintering

A method and apparatus for selectively sintering a layer of powder to produce a part comprising a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder dispensing mechanism includes a drum which is moved horizontally across the target area and counter-rotated to smooth and distribute the powder in an even layer across the target area. A downdraft system provides controlled temperature air flow through the target area to moderate powder temperature during sintering.Board of Regents, University of Texas Syste

Method for producing parts by infiltration of porous intermediate parts

A method and apparatus for selectively sintering a layer of powder to produce a part as a plurality of sintered layers. The apparatus includes a computer controlling a laser to direct the laser energy onto the powder to produce a sintered mass. The computer either determines or is programmed with the boundaries of the desired cross-sectional regions of the part. For each cross-section, the aim of the laser beam is scanned over a layer of powder and the beam is switched on to sinter only the powder within the boundaries of the cross-section. Powder is applied and successive layers sintered until a completed part is formed. Preferably, the powder dispensing mechanism includes a drum which is moved horizontally across the target area and counter-rotated to smooth and distribute the powder in an even layer across the target area. A downdraft system provides controlled temperature air flow through the target area to moderate powder temperature during sintering.Board of Regents, University of Texas Syste

Improved Energy Delivery For Selective Laser Sintering

Selective Laser Sintering (SLS) is a leadingtechnology in the important new area of Solid Freeform Fabrication (also ca1ledR.apid Prototyping). Selective Laser Sintering produces freeform parts directly from a CAD model by building the parts up in layers from a powder. A laser is used to selectively melt each layer of powder to form the part. The laser beam is scanned across the powder using two galvanometer scanners. The energy delivery system (laser, optics, scanner and controls) is a critical component technology of SLS. Projects with the objective of improving the energy delivery system are underway at Clemson UniversityMechanical Engineerin