A variety of challenges related to measurement sciences limits the adoption of additive manufacturing for many industries that require qualified parts.
This project involved a three-part research plan to ensure that quality additive manufacturing (AM) parts are produced, and certified, for use in products manufactured by a variety of U.S. industries and their supply chains. This plan included 1.) in-situ process monitoring, 2.) non-destructive evaluation, and 3.) layerwise quality certification for AM.
Additive manufacturing (AM) presents a variety of measurement science challenges which limit the broad application of AM for performance-critical parts. Current commercial laser powder bed fusion (LPBF) machines operate in an “open loop” manner, with little or no real-time monitoring of the process to ensure quality requirements are consistently achieved.
The objective of this project was to address metallic material systems and manufacturing processes in three high priority thrust areas to:
- Develop, integrate, and validate a robust, informative in-situ process monitoring capability to ensure part quality
- Develop and validate a non-destructive evaluation (NDE) standard to establish quality certification methods well suited to AM
- Create a 3D Quality Certificate (3DQC) for each manufactured part using run-time process monitoring data indexed to part geometry
These thrust areas would help ensure that quality parts are produced and certified for use in end products across multiple manufacturing industries.
The measurement science challenges were divided into three focused research tracks:
In-Process Sensing and Monitoring
Led by EWI, this research team evaluated, developed, and integrated a variety of thermal, visual, and acoustic sensing techniques on an LPBF platform. Evaluation techniques included variable part quality conditions and industrial printing systems.
The team led by Concurrent Technologies Corporation (CTC) focused on maturing flaw seeding techniques within test specimens and establishing accurate and reliable NDE size limitations for detecting the seeded flaws.
Layerwise Certification Standards for AM
The research team led by the University of Louisville used thermal monitoring of each layer during a part build and compared it to a layer-by-layer quality certification template created from the STL file for the component. This produced a Layerwise Quality Certification standard that can be used for the AM industry.
The combined efforts from each of the three tracks of this project have led to broader applications of AM for performance-critical components through qualification and certification standards, post-build inspection and verification, and through deployment of novel in-situ sensors and techniques that can be adapted to any industrial AM process.
Specific accomplishments include:
- An open architecture sensor test bed for LPBF was designed and fabricated with the ability to control defect generation and detection
- The following sensors were successfully integrated and tested in the LPBF test bed:
- High Speed Thermal Imager
- Infrared-Based Thermal Imager
- Visible Range Machine Vision Imager
- Laser-Based Profilometer
- Airborne Acoustic Microphone
- The following advanced sensing techniques were tested:
- Fringe Projection
- Surface Acoustic Waves
- Machine Vision Defect Algorithms
- Visual Light Pool Imaging
- An NDE baseline showing limits for a variety of materials produced with LPBF technology was established. Other materials and processes can leverage this baseline.
- A 3D Quality Certificate template was created.
Other Project Participants
- Concurrent Technologies Corporation
- University of Louisville
- U.S. Department of Commerce
- National Institute of Standards and Technology