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AssigneeDTM Corporation
InventorsElmer D. Dickens, Jr., Biing Lin Lee, Glenn A. Taylor, Angelo J. Magistro, Hendra Ng
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A laser-sinterable powder product has been prepared having unique properties which allow the powder to be sintered in a selective laser sintering (SLS) machine to form a sintered part which is near-fully dense. For most purposes, the sintered part is indistinguishable from another part having the same dimensions made by isotropically molding the powder. In addition to being freely flowable at a temperature near its softening temperature, the powder has a two-tier distribution in which substantially no primary particles has an average diameter greater than 180.mu.m, provided further that the number average ratio of particles smaller than 53.mu.m is greater than 80%, the remaining larger particles being in the size range from 53.mu.m to 180.mu.m. When the powder is a semicrystalline synthetic resin having a number average molecular weight in the range from about 30,000 to 500,000; a molecular weight distribution M.sub.w /M.sub.n in the range from 1 to 5; and, provides a window of sinterability in the temperature range from near the powder's softening temperature T.sub.s to its caking temperature T.sub.c, it is sintered layer-upon layer to form a near-fully dense part of arbitrary shape.
A laser-sinterable powder product, adapted to be sintered in a selective laser sintering machine to form a sintered part, said powder consisting essentially of an unblended .polymer which provides signs of crystalline order under X-ray examination, and shows a crystalline melting point Tm as well as a glass transition temperature Tg, said polymer having a two-tier particle size distribution said powder having the following properties:
A bed of a laser-sinterable powder in a selective laser sintering zone, said bed consisting essentially of particles of an unblended synthetic resinous material which provides signs Of crystalline order under X-ray examination, and shows a crystalline melting point Tm as well as a glass transition temperature Tg, said material in particulate form having a two-tier particle size distribution from which powder, a laser-sintered part is formed and removably embedded in said bed, said powder being a freely-flowable semi-crystalline powder having primary particles in the size range smaller than 180.mu.m and a sphericity in the range from greater than 0.5 to 0.9, provided further that the number average ratio of particles smaller than 53.mu.m is greater than 80%, the remaining larger particles being in the size range from 53.mu.m to 180.mu.m;
A bed of a laser-sinterable powder in a selective laser sintering zone, said bed consisting essentially of finely divided particles of an unblended synthetic resinous material which provides signs of crystalline order under X-ray examination, and Shows a crystalline melting point Tm as well as a glass transition temperature Tg, said material in finely divided particulate form having a two-tier particle size distribution from which particles a laser-sintered part is formed, said powder being a freely-flowable semi-crystalline powder having a crystallinity measured by differential scanning calorimetry in the range from 10% to 90%, said powder having primary particles in the size range smaller than 180.mu.m, having a sphericity in the range from greater than 0.5 to 0.9, provided further that the number average ratio of particles smaller than 53.mu.m is greater than 80%, the remaining larger particles being in the size range from 53.mu.m to 180.mu.m;
A laser-sintered article or `part` of arbitrary shape sintered in a selective laser sintering machine containing a laser-sinterable powder of a semi-crystalline synthetic resin, said part consisting essentially of a sintered mass of said powder, said part having a density in the range from 80% to 90% of the density of an isotropically molded part of said powder and fracture surfaces, when broken by bending, which are visually identical to fracture surfaces of said molded part but including a profusion of cavities having an average diameter in the range from 1.mu.m-30.mu.m randomly scattered throughout said part which has substantially the same flexural modulus and maximum stress at yield (psi) when fractured in bending, but substantially less ultimate elongation (%), and notched Izod impact (ftlb/in), than a compression molded article molded from a portion of said powder.
Dependencies are inferred from the claim text.