Multiple material systems for selective beam sintering

• US 5,296,062 A
• Filed: 09/25/1992
• Issued: 03/22/1994
• Est. Priority Date: 10/17/1986
• Status: Expired due to Term

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Beaman, Joseph L., Marcus, Harris L., Bourell, David L., Barlow, Joel W., Deckard, Carl R.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/951,349
• Time in Patent Office: 543 Days
• Field of Search: 156/62.2, 156/89, 156/272.8, 156/278, 156/242, 156/245, 156/643, 156/345, 156/654, 156/655, 156/656, 156/657, 156/668, 219/121.6, 219/121.61, 219/121.63, 219/121.65, 219/121.66, 219/121.73, 219/121.8, 219/121.85, 264/58, 264/22, 264/113, 264/125, 264/126, 264/127, 264/122, 264/219, 264/221, 264/308, 264/317, 425/174, 419/5, 419/8
• US Class Current: 156/62.2
• CPC Class Codes: B05C 19/00 Apparatus specially adapted for applying particulate materials to surfaces
• CPC Class Codes: B05C 19/008 Accessories or implements for use in connection with applying particulate materials to surfaces; not provided elsewhere in B05C19/00
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/366 Scanning parameters, e.g. hatch distance or scanning strategy
• CPC Class Codes: B22F 10/64 by thermal means control of energy beam parameters for post heating B22F10/364
• CPC Class Codes: B22F 12/22 Driving means
• CPC Class Codes: B22F 12/41 characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B22F 12/44 characterised by the configuration of the radiation means
• CPC Class Codes: B22F 12/49 Scanners
• CPC Class Codes: B22F 12/52 Hoppers
• CPC Class Codes: B22F 2003/1052 assisted by energy absorption enhanced by the coating or powder
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 3/004 Filling molds with powder feeding material to presses in general B30B15/302
• CPC Class Codes: B22F 3/105 by using electric current other than for infrared radiant energy, laser radiation or plasma B22F3/11 takes precedence; by ultrasonic bonding B22F3/115 takes precedence
• CPC Class Codes: B22F 3/26 Impregnating making ferrous alloys by impregnation C22C33/0242
• CPC Class Codes: B22F 7/02 of composite layers B22F7/002 takes precedence
• CPC Class Codes: B23K 26/08 Devices involving relative movement between laser beam and workpiece
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/34 Laser welding for purposes other than joining
• CPC Class Codes: B29C 35/045 : using gas or flames
• CPC Class Codes: B29C 41/12 : Spreading-out the material on a substrate , e.g. on the surface of a liquid
• CPC Class Codes: B29C 41/46 : Heating or cooling
• CPC Class Codes: B29C 64/153 : using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B33Y 10/00 : Processes of additive manufacturing
• CPC Class Codes: C04B 35/622 : Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C23C 24/08 : by application of heat or pressure and heat C23C24/04 takes precedence
• CPC Class Codes: C23C 24/10 : with intermediate formation of a liquid phase in the layer
• CPC Class Codes: C23C 26/02 : applying molten material to the substrate
• CPC Class Codes: G05B 19/41 : characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path G05B19/25, G05B19/31, G05B19/37, G05B19/39, G05B19/40 take precedence
• CPC Class Codes: G05B 2219/49013 : Deposit layers, cured by scanning laser, stereo lithography SLA, prototyping
• CPC Class Codes: G05B 2219/49018 : Laser sintering of powder in layers, selective laser sintering SLS
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

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.

Claims

1. A method of producing a part, comprising the steps of:

depositing a layer of a powder onto a target surface, said powder comprising particles of a first material coated with a second material, said second material having a lower softening temperature than said first material;

irradiating a selected portion of said powder corresponding to a cross-section of the part with a directed energy beam, so that the second material in said selected portion bonds particles of said first material;

repeating said depositing and irradiating steps for a plurality of layers so that bonded portions of adjacent layers bond to one another to form a mass;

removing unbonded portions of the powder to yield the mass; and

heating the mass after said removing step.

2. The method of claim 1, wherein said second material is driven off in said heating step;

and wherein said heating step fuses particles of said first material to one another.

3. The method of claim 2, wherein said second material comprises a polymer of the PMMA type.

4. The method of claim 1, wherein said first and second materials interact in said heating step.

5. The method of claim 1, wherein the thermal conductivity of said first material is substantially greater than that of said second material.

6. The method of claim 1, further comprising:

controlling the temperature of bonded and unbonded powder at the target surface.

7. The method of claim 6, wherein said controlling step comprises:

heating the powder at the target surface.

8. The method of claim 1, wherein said first and second materials have different absorptivity characteristics;

and wherein the wavelength of the directed energy beam is selected so as to be more highly absorbed by said second material than by said first material.

9. The method of claim 1, wherein the second material in said selected portions is sintered during said irradiating step in such a manner as to bond particles of said first material.

10. A method of producing a part, comprising the steps of:

depositing a layer of a powder onto a target surface, said powder comprising a first material and a second material, said second material having a lower softening temperature than said first material;

irradiating a selected portion of said powder corresponding to a cross-section of the part with a directed energy beam, so that the second material in said selected portion bonds particles of said first material;

during said irradiating step, exposing said powder to a gas phase to promote infiltration of the second material within particles of the first material;

repeating said depositing, irradiating and exposing steps for a plurality of layers so that bonded portions of adjacent layers fuse to one another to form a mass; and

removing unbonded portions of the powder to yield the mass.

11. The method of claim 10, wherein said gas phase is inert.

12. The method of claim 10, wherein said gas phase is active.

13. The method of claim 10, wherein said first material is copper and said second material is tin.

14. The method of claim 10, wherein said first material is tungsten carbide and said second material is cobalt.

15. The method of claim 10, wherein the second material at the selected portion of the powder in said irradiating step is sintered in such a manner as to bond particles of said first material.

16. A method of producing a part, comprising the steps of:

depositing a layer of a powder onto a target surface, said powder comprising a first material and a second material, said second material being a metal and having a lower softening temperature than said first material;

irradiating a selected portion of said powder corresponding to a cross-section of the part with a directed energy beam, so that the second material in said selected portion bonds particles of said first material;

repeating said depositing and irradiating steps for a plurality of layers so hat bonded portions of adjacent layers fuse to one another to form a mass; and

removing unbonded portions of the powder to yield the mass.

17. The method of claim 16, further comprising:

heating the mass after said removing step so that the second material infiltrates the first material within the mass.

18. The method of claim 17, wherein said first material is copper and said second material is tin.

19. The method of claim 16, wherein the second material in said selected portion of said powder is sintered in said irradiating step in such a manner as to bond particles of said first material.