# US 8,540,505 B2 · Core-shell solid freeform fabrication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,540,505 B2 - Document ID: US8540505B2 - Status: Granted - Kind: B2 - Application number: 12/891,185 - Filed: 2010-09-27 - Published: 2011-03-31 - Granted: 2013-09-24 - Earliest claimed: 2005-02-25 - Assignees: Hewlett-Packard Development Company, L.P. - Applicants: Isaac Farr; Terry M. Lambright - Inventors: Isaac Farr; Terry M. Lambright - Web page: https://patentgrep.com/patent/US8540505B2 ## CPC - B29C 64/165: using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber - B33Y 10/00: Processes of additive manufacturing - B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor - B33Y 50/02: for controlling or regulating additive manufacturing processes - B33Y 70/10: Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials - B29K 2503/04: Inorganic materials - B29K 2995/0073: smooth - B29K 2995/0082: Flexural strength; Flexion stiffness - B33Y 80/00: Products made by additive manufacturing - Y10T 428/23: Sheet including cover or casing - Y10T 428/232: Encased layer derived from inorganic settable ingredient - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method for creating a three-dimensional solid freeform fabrication object includes spreading a reactive powder on a substrate, selectively dispensing a core binder in the reactive powder to form a core material, and selectively dispensing a shell binder in the reactive powder to form a shell on the core material. ## Claims ### Claim 1 A solid freeform fabrication system for producing a three-dimensional object comprising: a powder spreading system configured to spread a specified quantity of reactive powder; a dispensing system adapted to selectively dispense both a core binder and a shell binder onto said reactive powder, said dispensing system comprising a reservoir of said core binder and a separate reservoir of said shell binder, wherein said core binder is configured to react differently with said reactive powder so as to bind said powder with more flexural strength than said shell binder, and wherein said shell binder is configured to react differently with said reactive powder to as to provide a smoother surface finish than would said core binder; a curing system configured to cure said binder and reactive powder; and a computing device coupled to and configured to control said dispensing system and said curing system, wherein said computing device is programmed to selectively apply said shell binder to portions of said reactive powder which will be located at a surface of said three-dimensional object and to selectively apply said core binder to portions of said reactive powder that will be encased in a shell of said three-dimensional object that is formed by said shell binder. ### Claim 2 (depends on 1) The solid freeform fabrication system of claim 1, wherein said powder spreading system comprises a mechanical roller. ### Claim 3 (depends on 2) The solid freeform fabrication system of claim 2, wherein said mechanical roller is configured to planarize and pack a quantity of said reactive powder. ### Claim 4 (depends on 1) The solid freeform fabrication system of claim 1, wherein said dispensing system comprises at least one inkjet dispenser. ### Claim 5 (depends on 4) The solid freeform fabrication system of claim 4, wherein said inkjet dispenser comprises one of a thermally actuated inkjet dispenser, a mechanically actuated inkjet dispenser, an electrostatically actuated inkjet dispenser, a magnetically actuated dispenser, a piezoelectrically actuated dispenser, or a continuous inkjet dispenser. ### Claim 6 (depends on 4) The solid freeform fabrication system of claim 4, wherein said inkjet dispenser comprises a plurality of material reservoirs configured to chemically separate a core binder and a shell binder. ### Claim 7 (depends on 1) The solid freeform fabrication system of claim 1, wherein said shell binder comprises an aqueous fluid. ### Claim 8 (depends on 1) The solid freeform fabrication system of claim 1, wherein said reactive powder comprises a polymerization initiator and a fast-setting cement. ### Claim 9 (depends on 8) The solid freeform fabrication system of claim 8, wherein said fast-setting cement comprises one of a calcium phosphate or a calcium sulfate. ### Claim 10 (depends on 1) The solid freeform fabrication system of claim 1, wherein said core binder comprises an acrylate. ### Claim 11 (depends on 1) The solid freeform fabrication system of claim 1, wherein said reactive powder comprises one of a calcium phosphate or a calcium sulfate. ### Claim 12 (depends on 1) The solid freeform fabrication system of claim 1, wherein said shell binder comprises one of an aqueous fluid or a phosphoric acid. ### Claim 13 (depends on 1) The solid freeform fabrication system of claim 1, said computing device further configured to operate said dispensing and curing systems to produce an object having a core with flexural strength; and a smooth shell coating a surface of said core. ### Claim 14 (depends on 1) The solid freeform fabrication system of claim 1, wherein said dispensing system comprises a number of material dispensers and said solid freeform fabrication system utilizes a higher number of said material dispensers to dispense said core binder than said shell binder when more of said core binder is needed to form said three-dimensional object than said shell binder. ### Claim 15 (depends on 1) The solid freeform fabrication system of claim 1, wherein said dispensing system comprises a number of material dispensers and said solid freeform fabrication system utilizes a higher number of said material dispensers to dispense said shell binder than said cure binder when more of said shell binder is needed to form said three-dimensional object than said core binder.