Method for building three-dimensional objects in extrusion-based additive manufacturing systems using core-shell consumable filaments

• US 8,920,697 B2
• Filed: 03/14/2012
• Issued: 12/30/2014
• Est. Priority Date: 09/17/2010
• Status: Active Grant

• Current Assignee: Stratasys Incorporated
• Original Assignee: Stratasys Incorporated
• Inventors: Mikulak, James K., Deckard, Carl R., Zinniel, Robert L.
• Primary Examiner(s): Tentoni, Leo B
• Application Number:
  US13/419,669
• Publication Number:
  US 20120231225A1
• Time in Patent Office: 1,021 Days
• Field of Search: 264/308, 264/317, 264/255
• US Class Current: 264/255
• CPC Class Codes: B29C 2948/92704 Temperature
• CPC Class Codes: B29C 48/0021 combined with joining, lining or laminating
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/07 Flat, e.g. panels
• CPC Class Codes: B29C 48/154 Coating solid articles, i.e. non-hollow articles
• CPC Class Codes: B29C 48/16 Articles comprising two or more components, e.g. co-extruded layers
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/92 Measuring, controlling or regulating
• CPC Class Codes: B29C 64/118 using filamentary material being melted, e.g. fused deposition modelling [FDM]
• CPC Class Codes: B29C 64/188 involving additional operations performed on the added layers, e.g. smoothing, grinding or thickness control surface shaping B29C59/00; after-treatment of articles without altering their shape B29C71/00
• CPC Class Codes: B29C 64/40 Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
• CPC Class Codes: B32B 3/26 characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids foam layer B32B5/18; layer of synthetic resin characterised by fillers that create voids or cavities B32B27/205; characterised by an apertured layer
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: D01F 8/04 from synthetic polymers
• CPC Class Codes: D01F 8/12 with at least one polyamide as constituent
• CPC Class Codes: Y10T 428/23 Sheet including cover or casing
• CPC Class Codes: Y10T 428/24612 Composite web or sheet
• CPC Class Codes: Y10T 428/2929 Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]

Abstract

A consumable filament for use in an extrusion-based additive manufacturing system, where the consumable filament comprises a core portion of a first thermoplastic material, and a shell portion of a second thermoplastic material that is compositionally different from the first thermoplastic material, where the consumable filament is configured to be melted and extruded to form roads of a plurality of solidified layers of a three-dimensional object, and where the roads at least partially retain cross-sectional profiles corresponding to the core portion and the shell portion of the consumable filament.

Claims

1. A method for building a three-dimensional object with an additive manufacturing system having an extrusion head, the method comprising:

feeding a consumable filament to the extrusion head, the consumable filament comprising a longitudinal length, a core portion extending along the longitudinal length, and a shell portion extending along the longitudinal length and substantially encasing the core portion, wherein the core portion compositionally comprises a first thermoplastic material, and wherein the shell portion compositionally comprises a second thermoplastic material that is different from the first thermoplastic material;

melting the fed consumable filament in the extrusion head to form molten material;

depositing the molten material as an extruded road that defines at least a portion of a layer of the three-dimensional object, wherein the extruded road comprises a core region of the first thermoplastic material, and a shell region of the second thermoplastic polymeric material; and

solidifying the extruded road.

2. The method of claim 1, wherein the first thermoplastic material is a first semi-crystalline polymeric material having a first peak crystallization temperature, and wherein the second thermoplastic material is a second semi-crystalline polymeric material having a second peak crystallization temperature that is greater than the first peak crystallization temperature.

3. The method of claim 2, wherein the additive manufacturing system includes a heated build chamber, and wherein the method further comprises maintaining an environment within the heated build chamber at one or more temperatures that are about equal to, or are within a range of about 10°

C. above or below, the peak crystallization temperature of the second semi-crystalline polymeric material.

4. The method of claim 1, wherein the consumable filament is a support material consumable filament and the three-dimensional object is a support structure for a three-dimensional model, and wherein the method further comprises:

building a layer of the three-dimensional model with the additive manufacturing system, wherein the layer of the three-dimensional model is supported by the solidified layer of the support structure; and

removing the support structure from the three-dimensional model.

5. The method of claim 4, wherein the second thermoplastic material is at least partially soluble in an aqueous solution, and wherein removing the support structure from the three-dimensional model comprises at least partially dissolving the second thermoplastic material in the aqueous solution.

6. The method of claim 4, wherein the second thermoplastic material of the shell portion comprises a colorant, and wherein the shell of the extruded road also includes the colorant.

7. The method of claim 1, wherein the consumable filament comprises a cylindrical geometry along the longitudinal length.

8. The method of claim 1, wherein the consumable filament has an average cross-sectional area ranging from about 0.5 square millimeters to about 8 square millimeters.

9. A method for building a three-dimensional model and associated support structure with an additive manufacturing system retaining an extrusion head, the method comprising:

feeding a consumable filament to the extrusion head, the consumable filament comprising;

a longitudinal length;

a core portion extending along the longitudinal length, wherein the core portion compositionally comprises a first thermoplastic material; and

a shell portion extending along the longitudinal length and substantially encasing the core portion, wherein the shell portion compositionally comprises a second thermoplastic material that is different from the first thermoplastic material, and wherein the second thermoplastic material is soluble in an aqueous liquid;

melting the fed consumable filament in the extrusion head to form a molten material;

depositing the molten material in the heated build chamber to form a series of extruded roads for a layer of the support structure, wherein at least a portion of the extruded roads each comprise a core region of the first thermoplastic material and a shell region of the second thermoplastic material;

at least partially solidifying the layer; and

building a layer of the three-dimensional model from a modeling material with the additive manufacturing system, wherein the layer of the three-dimensional model is supported by the at least partially solidified layer of the support structure.

10. The method of claim 9, wherein the first thermoplastic material of the core portion has a creep relaxation temperature that is within about 20°

C. of a creep relaxation temperature of the modeling material.

11. The method of claim 10, wherein the creep relaxation temperature of the first thermoplastic material is within about 10°

C. of the creep relaxation temperature of the modeling material.

12. The method of claim 11, wherein the creep relaxation temperature of the first thermoplastic material is within about 5°

C. of the creep relaxation temperature of the modeling material.

13. The method of claim 9, wherein the aqueous liquid that the second thermoplastic material is soluble in comprises an alkaline aqueous solution.

14. The method of claim 9, wherein the first thermoplastic material of the core portion has a tensile strength that is higher than a tensile strength of the second thermoplastic material of the shell portion.

15. The method of claim 9, wherein the first thermoplastic material of the core portion is substantially the same as the modeling material.

16. The method of claim 9, wherein the additive manufacturing system includes a heated build chamber, and wherein the method further comprises maintaining an environment within the heated build chamber at one or more temperatures that are between about a solidification temperature of the modeling material and a creep relaxation temperature of the modeling material.

17. The method of claim 9, wherein the core portion of the consumable filament has an average cross-sectional area that is greater than an average cross-sectional area of the shell portion.

18. The method of claim 9, wherein the consumable filament comprises a cylindrical geometry along the longitudinal length.

19. The method of claim 9, wherein the first thermoplastic material of the core portion is not soluble in the aqueous liquid.

20. The method of claim 9, and further comprising exposing the support structure to the aqueous liquid to remove the support structure from the three-dimensional model.