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AI software enables real-time 3D printing quality assessment

Oak Ridge National Laboratory researchers have developed artificial intelligence software for powder bed 3D printers that assesses the quality of parts in real time, without the need for expensive characterization equipment.

The software, named Peregrine, supports the advanced manufacturing “digital thread” being developed at ORNL that collects and analyzes data through every step of the manufacturing process, from design to feedstock selection to the print build to material testing.

“Capturing that information creates a digital ‘clone’ for each part, providing a trove of data from the raw material to the operational component,” said Vincent Paquit, who leads advanced manufacturing data analytics research as part of ORNL’s Imaging, Signals and Machine Learning group. “We then use that data to qualify the part and to inform future builds across multiple part geometries and with multiple materials, achieving new levels of automation and manufacturing quality assurance.”

The digital thread supports the factory of the future in which custom parts are conceived using computer-aided design, or CAD, and then produced by self-correcting 3D printers via an advanced communications network, with less cost, time, energy and materials compared with conventional production. The concept requires a process control method to ensure that every part rolling off printers is ready to install in essential applications like cars, airplanes, and energy facilities.

To devise a control method for surface-visible defects that would work on multiple printer models, ORNL researchers created a novel convolutional neural network — a computer vision technique that mimics the human brain in quickly analyzing images captured from cameras installed on the printers. The Peregrine software uses a custom algorithm that processes pixel values of images, taking into account the composition of edges, lines, corners and textures. If Peregrine detects an anomaly that may affect the quality of the part, it automatically alerts operators so adjustments can be made.

The software is well suited to powder bed printers. These printers distribute a fine layer of powder over a build plate, with the material then melted and fused using a laser or electron beam. Binder jetting systems rely on a liquid binding agent rather than heat to fuse powdered materials.

The systems print layer by layer, guided by the CAD blueprint, and are popular for the production of metal parts. However, during the printing process, problems such as uneven distribution of the powder or binding agent, spatters, insufficient heat, and some porosities can result in defects at the surface of each layer. Some of those issues may happen in such a very short timeframe that they may go undetected by conventional techniques.

“One of the fundamental challenges for additive manufacturing is that you’re caring about things that occur on length-scales of tens of microns and happening in microseconds, and caring about that for days or even weeks of build time,” said ORNL’s Luke Scime, principal investigator for Peregrine. “Because a flaw can form at any one of those points at any one of those times, it becomes a challenge to understand the process and to qualify a part.”

Peregrine is being tested on multiple printers at ORNL, including as part of the Transformational Challenge Reactor (TCR) Demonstration Program that is pursuing the world’s first additively manufactured nuclear reactor. TCR is leveraging ORNL’s rich history in nuclear science and engineering, materials science and advanced manufacturing to develop a microreactor with newer materials in less time at a lower cost, ensuring the future of this important carbon-free energy source.

“For TCR in particular, you could have a scenario in which the regulator will want detailed data on how a part was manufactured, and we can provide specs with the database built using Peregrine,” Scime said.

“Establishing correlations between these signatures collected during manufacturing and performance during operation will be the most data-rich and informed process for qualifying critical nuclear reactor components,” said Kurt Terrani, TCR program director. “The fact that it may be accomplished during manufacturing to eliminate the long and costly conventional qualification process is the other obvious benefit.”

ORNL researchers stress that by making the Peregrine software machine-agnostic — able to be installed on any powder bed system — printer manufacturers can save development time while offering an improved product to industry. Peregrine produces a common image database that can be transferred to each new machine to train new neural networks quickly, and it runs on a single high-powered laptop or desktop. Standard cameras were used in the research, ranging in most cases from 4 to 20 megapixels and installed so they produce images of the print bed at each layer. The software has been tested successfully on seven powder bed printers at ORNL so far, including electron beam melting, laser powder bed, and binder jetting, as detailed in the journal Additive Manufacturing.

“Anything we can do to help operators and designers know what works and what doesn’t helps with the confidence that the part will be okay for use,” Scime said. “When you have a 3D map of every pixel where the network thinks there is an anomaly and what it thinks the problem is, it opens up a whole world of understanding of the build process.”

As the monitoring system has evolved, Scime said researchers are able to combine the image data with data from other sources such as the printer’s log files, the laser systems and operator notes, allowing parts to be uniquely identified and statistics from all parts tracked and evaluated.

The AI software was developed at the Manufacturing Demonstration Facility at ORNL, a U.S. Department of Energy user facility that works closely with industry to develop, test and refine nearly every type of modern advanced manufacturing technology.

“There’s no place else like the MDF where this machine-agnostic algorithm could have been developed, simply because we have so many machines and so many builds going on all the time in the course of our research,” Scime said. “Access to data is key. Here, we have the ability to place sensors easily and the technicians to make sure everything works and that we’re getting our data. With the variety of scientific expertise available here, it’s been easy to find experts to help with all the challenges involved.”

In other process control work, MDF researchers are developing methods to monitor for defects on the subsurface of builds and to detect porosity that may form in deeper layers, including the use of photodiodes and high-speed cameras.

“We’ve been doing welding for hundreds of years, but additive has only been around for a couple of decades and we don’t know what the problems look like in some cases,” Scime said. “Machine learning techniques allow us to collect and analyze a lot of data quickly. We can then identify those problems and gain the knowledge we need to better understand and prevent anomalies.”

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3D Printing Industry

Farsoon debuts its FS621M large-format metal 3D printer at TCT Asia 

Chinese SLM and SLS 3D printer manufacturer Farsoon, has introduced it’s latest Laser Beam Powder Bed Fusion (LPBF) large-format metal 3D printer, the FS621M.  Developed with industry partner and manufacturing service provider Falcontech, the new system has been designed to address the productivity challenges of metal 3D printing including size constraints, powder management and process […]

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Author: Paul Hanaphy

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Farsoon debuts its Flight 252P 3D printer and two new industrial polymers

Powder bed fusion specialist Farsoon has announced its new high temperature 252P series of polymer SLS 3D printers. The set comprises two variants, the ST252P (higher power) and the HT252P (lower power), and features the company’s proprietary Flight technology. Farsoon will also be releasing two new plastic powder materials to complement the 252P with the […]

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Author: Kubi Sertoglu

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Braskem launches 3D printing materials portfolio 

Brazilian petrochemical company Braskem, will add polyolefin-based filament, powder, and pellets for 3D printing, to its material portfolio.  Polypropylene (PP) is a recyclable thermoplastic that displays high impact strength and durability, making it suitable for 3D printing applications such as creating functional prototypes and models.  “We are excited about the capabilities our polypropylene has over […]

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Author: Paul Hanaphy

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TU Graz engineers create metal 3D printer that uses LED instead of lasers or electron beams

Engineers at Graz University of Technology (TU Graz), Austria, have developed a new metal powder additive manufacturing system that relies on LED instead of laser sources to melt powder. The 3D printer uses a process known as selective LED-based melting (SLEDM), developed by a team led by Franz Haas, head of the Institute of Production […]

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Author: Anas Essop

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New technology revolutionizes 3D metal printing

Selective LED-based melting (SLEDM) — i.e. the targeted melting of metal powder using high-power LED light sources — is the name of the new technology that a team led by Franz Haas, head of the Institute of Production Engineering at TU Graz, has developed for 3D metal printing and has now applied for a patent. The technology is similar to selective laser melting (SLM) and electron beam melting (EBM), in which metal powder is melted by means of a laser or electron beam and built up into a component layer by layer. However, SLEDM solves two central problems of these powder bed-based manufacturing processes: the time-consuming production of large-volume metal components and the time-consuming manual post-processing.

Reduced production time

Unlike the SLM or EBM processes, the SLEDM process uses a high-power LED beam to melt the metal powder. The light-emitting diodes used for this purpose were specially adapted by the west Styrian lighting specialist Preworks and equipped with a complex lens system by which the diameter of the LED focus can be easily changed between 0.05 and 20 millimetres during the melting process. This enables the melting of larger volumes per unit of time without having to dispense with filigree internal structures, thus reducing the production time of components for fuel cell or medical technology, for example, by a factor of 20 on average.

Tedious reworking is no longer necessary

This technology is combined with a newly designed production plant which — in contrast to other metal melting plants — adds the component from top to bottom. The component is thus exposed, the required amount of powder is reduced to a minimum and the necessary post-processing can be carried out during the printing process. “The time-consuming, usually manual reworking that is necessary with current methods, for example, smoothing rough surfaces and removing supporting structures, is no longer necessary and saves further valuable time,” says Haas.

Fields of application and further plans

A demonstrator of the SLEDM process is already being considered in the K-Project CAMed of the Medical University of Graz, where the first laboratory for medical 3D printing was opened in October 2019. The process will be used to produce bioresorbable metal implants, i.e. preferably screws made of magnesium alloys that are used for bone fractures. These implants dissolve in the body after the fracture site has grown together. A second operation, which is often very stressful for people, is therefore no longer necessary. Thanks to SLEDM, the production of such implants would be possible directly in the operating theatre, because “an LED light is naturally less dangerous for the operation than a powerful laser source,” says Haas.

The second focus is on sustainable mobility, namely the production of components such as bipolar plates for fuel cells or components for battery systems. “We want to make additive manufacturing using SLEDM economically viable for e-mobility and position SLEDM in this field of research at an early stage,” says Haas, who will produce a marketable prototype of this 3D metal printer — “made by TU Graz” — in the next development step: a further innovation in the university environment.

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Materials provided by Graz University of Technology. Note: Content may be edited for style and length.

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Equispheres raises $30 million in Series B funding

Equispheres, the Canadian additive manufacturing powder producer, has announced that it has raised $30 million (CDN) in Series B investment.  The funding round was led by advanced materials and sustainable technology investor, HG Ventures, the firm’s first foray into additive manufacturing. Government agency Sustainable Development Technology Canada (SDTC) and federal bank Business Development Bank of […]

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Author: Anas Essop

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Wayland Additive unveils new electron beam powder bed fusion technology – NeuBeam

UK-based engineering firm Wayland Additive has announced the development of its new electron beam powder bed fusion technology – NeuBeam. After licensing the process from parent company Reliance Precision, Wayland hopes to commercialize it and fulfil six deliveries of the system by the end of the year. Charge neutral 3D printing According to Will Richardson, […]

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Author: Kubi Sertoglu

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3D Printing Industry

Lubrizol TPU powder passes ISO tests for skin contact

Lubrizol, an Ohio-based chemicals and materials company, has announced that its ESTANE 3D TPU M95A powder for 3D printing has passed skin sensitization and cytotoxicity tests in accordance with ISO 10993-5 and 10993-10. The successful tests means that the material, designed for use with HP Multi Jet Fusion (MJF) technology, can now be used by […]

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Author: Anas Essop

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3D Printing Industry

University of Washington research explores the effects of powder reuse on 3D printed metal part quality

A new study by researchers from the University of Washington investigates the effects of powder reuse on 3D printed part quality. The paper, published in the journal Materialia, is primarily concerned with the powder bed fusion of Ti6Al4V – commercially-available grade 5 Titanium alloy. Additive manufacturing for aerospace applications When manufacturing for safety-critical applications such […]

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Author: Kubi Sertoglu