# US 11,027,332 B2 · System and method for in-situ characterization and inspection of additive manufacturing deposits using transient infrared thermography

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- Number: US 11,027,332 B2
- Document ID: US11027332B2
- Status: Granted
- Kind: B2
- Application number: 15/487,564
- Filed: 2017-04-14
- Published: 2017-10-19
- Granted: 2021-06-08
- Earliest claimed: 2016-04-15
- Assignees: United States of America as represented by the Administrator of NASA
- Applicants: U.S.A., as represented by the Administrator of the National Aeronautics and Space Administration
- Inventors: Joseph N. Zalameda; Eric R. Burke; Robert A. Hafley; Christopher S. Domack
- Web page: https://patentgrep.com/patent/US11027332B2

## CPC

- B22D 23/003: {Moulding by spraying metal on a surface}
- B22D 46/00: Controlling, supervising, not restricted to casting covered by a single main group, e.g. for safety reasons (controlling or regulating in general G05)
- B22F 3/115: by spraying molten metal, i.e. spray sintering, spray casting
- B22F 10/22: Direct deposition of molten metal
- B22F 10/25: Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
- B22F 10/38: to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures
- B22F 12/90: Means for process control, e.g. cameras or sensors
- B29C 64/393: for controlling or regulating additive manufacturing processes
- 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
- B22F 10/36: of energy beam parameters
- B22F 10/85: for controlling or regulating additive manufacturing processes
- Y02P 10/25: Process efficiency
- B22D: CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES (shaping of plastics or substances in a plastic state B29C; metallurgical processing, selection of substances to be added to metal C21, C22)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- 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
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Systems and methods are provided for the real time inspection of additive manufacturing deposits using infrared thermography. Various embodiments may enable the measurement of material properties and the detection of defects during the additive manufacturing process. Various embodiments may enable the characterization of deposition quality, as well as the detection of deposition defects, such as voids, cracks, disbonds, etc., as a structure is manufactured layer by layer in an additive manufacturing process. Various embodiments may enable quantitative inspection images to be archived and associated with the manufactured structure to document the manufactured structure's structural integrity.

## Claims

### Claim 1

An additive manufacturing system, comprising:
a deposition head comprising:
a heat source;
a wire feeder; and
one or more thermal imagers configured to sequentially in time capture thermal images of deposition of feed material heated by the heat source to form a structure layer by layer; and
a processor connected to the one or more thermal imagers, wherein the processor is configured to:
reconstruct thermal images from the sequentially in time captured thermal images, wherein reconstructing the thermal images comprises combining a number of the sequentially in time captured thermal images of the deposition for a given time period by pixel point location in the sequentially in time captured thermal images such that the reconstructed thermal images represent the deposition's transient temperature response spatially across all the in line pixel points and temporally at each respective pixel point for the given time period;
process the reconstructed thermal images to detect a defect in the structure based on the transient temperature response of at least one of the in line pixel points in the reconstructed thermal images; and
adjust deposition of the feedstock or adjust the heat source in response to detecting the defect.

### Claim 2 (depends on 1)

The system of claim 1, wherein the one or more thermal imagers are one or more infrared cameras.

### Claim 3 (depends on 2)

The system of claim 2, wherein the one or more thermal imagers are two infrared cameras.

### Claim 4 (depends on 2)

The system of claim 2, wherein the one or more thermal imagers are four infrared cameras.

### Claim 5 (depends on 2)

The system of claim 2, wherein the processor is further configured to flag the detected defect and store the reconstructed thermal images including the flag.

### Claim 6 (depends on 2)

The system of claim 2, wherein the transient temperature response of the at least one of the pixel points in the reconstructed thermal images is a temperature change over the given time period determined based at least in part on an intensity count of the at least one of the pixel points over the given time period.

### Claim 7 (depends on 6)

The system of claim 6, wherein processing the reconstructed thermal images to detect the defect in the structure comprises comparing the reconstructed thermal images to a thermal model.

### Claim 8 (depends on 7)

The system of claim 7, wherein the thermal model is a function of one or more of time, deposit direction, deposit velocity, thermal conductivity of the feed material, thermal diffusivity of the feed material, and deposit geometry.

### Claim 9 (depends on 2)

The system of claim 2, wherein the captured thermal images provide full coverage of a build process including inner and outer walls of the deposition and capture the geometry of the deposition.

### Claim 10

An additive manufacturing method, comprising:
reconstructing thermal images from sequentially in time captured thermal images received from one or more thermal imagers configured to capture thermal images sequentially in time of deposition of feed material heated by a heat source to form a structure layer by layer, wherein reconstructing the thermal images from the sequentially in time captured thermal images comprises combining a number of sequentially in time captured thermal images of the deposition for a given time period by pixel point location in the sequentially in time captured thermal images such that the reconstructed thermal images represent the deposition's transient temperature response spatially across all the pixel points and temporally at each respective pixel point for the given time period;
processing the reconstructed thermal images to detect a defect in the structure based on the transient temperature response of at least one of the pixel points in the reconstructed thermal images; and
adjusting deposition of the feedstock or adjusting the heat source in response to detecting the defect.

### Claim 11 (depends on 10)

The method of claim 10, wherein the one or more thermal imagers are one or more infrared cameras.

### Claim 12 (depends on 11)

The method of claim 11, wherein the one or more thermal imagers are two infrared cameras.

### Claim 13 (depends on 11)

The method of claim 11, wherein the one or more thermal imagers are four infrared cameras.

### Claim 14 (depends on 11)

The method of claim 11, further comprising flagging the detected defect and storing the reconstructed thermal images including the flag.

### Claim 15 (depends on 11)

The method of claim 11, wherein the transient temperature response of the at least one of the pixel points in the reconstructed thermal images is a temperature change over the given time period determined based at least in part on an intensity count of the at least one of the pixel points over the given time period.

### Claim 16 (depends on 11)

The method of claim 11, wherein processing the reconstructed thermal images to detect the defect in the structure comprises comparing the reconstructed thermal images to a thermal model.

### Claim 17 (depends on 16)

The method of claim 16, wherein the thermal model is a function of one or more of time, deposit direction, deposit velocity, thermal conductivity of the feed material, thermal diffusivity of the feed material, and deposit geometry.

### Claim 18 (depends on 11)

The method of claim 11, wherein the captured thermal images provide full coverage of a build process including inner and outer walls of the deposition and capture the geometry of the deposition.