From rubble to rockets: Turning scrap metal into essential equipment
WPI researchers aim to revolutionize on-site additive manufacturing by combining materials science, artificial intelligence, and 3D printing
Worcester Polytechnic Institute
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WPI student researchers in advanced manufacturing lab
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Worcester Polytechnic Institute (WPI) has been awarded $6.3 million for a groundbreaking initiative that could transform additive manufacturing by enabling the rapid production of high-quality components from scrap metal. This innovative approach to additive manufacturing, funded by the Defense Advanced Research Projects Agency (DARPA), aims to ensure that essential components can be produced even in the most resource-limited environments, including where access to traditional supply chains is limited, such as battlefields or remote search-and-rescue locations.
The initiative, called “Rubble to Rockets,” applies a machine-learning approach to identify materials—like scrap metal and mixed alloys—and understand how they react and bond together before being melted, mixed, and 3D-printed to form new parts that are strong and reliable. Traditional 3D-printing methods require carefully controlled materials and repeated testing and adjusting, something that’s not always possible in real-world settings.
“This work is crucial as it allows us to build high-quality components from unknown source materials with new confidence,” said Associate Professor Danielle Cote, Harold L. Jurist ’61 and Heather E. Jurist Dean’s Professor of Mechanical and Materials Engineering, and the lead researcher on the project. “Our goal is not just to build a single solution but to create a framework that guides future innovations. By improving our predictions and understanding of material performance, we can pave the way for new advancements in additive manufacturing from diverse and unpredictable sources.”
The team will use artificial intelligence (AI) technology developed by a WPI PhD student to predict material behavior at various compositions, optimizing and automating the characterization processes. By streamlining the procedure, the product can be manufactured at a rapid pace but not at the expense of durability and strength.
Researchers will design a proof-of-concept sounding rocket to test the structural integrity of mixed metals and measure performance and reliability.
Wider applications and future impact
Beyond defense applications, this work has broad applications across industries such as energy and transportation. The approach could be deployed in submarines, aircraft carriers, disaster relief zones, and remote locations where traditional supply chains are difficult to maintain. By addressing key risks, including material performance, equipment size, and predictive model accuracy, the innovation is paving the way for more resilient and sustainable manufacturing solutions that support both emergency response and long-term infrastructure needs.
As part of the project, the WPI team will work with subcontractors, including two WPI-alumni led companies as well as Siemens and two small businesses out of California: Nightshade Corporation will convert scrap into powder and Citrine Informatics will focus on AI and machine learning. This underscores the project’s crucial role in workforce development. By integrating advanced material informatics, AI-driven decision-making, and innovative additive manufacturing technologies, the initiative is helping to train the next generation of engineers and scientists, ensuring a skilled workforce that can sustain and expand these innovations into the future.
“The future of manufacturing is at the intersection of so many disciplines, including software, robotics, AI, materials science, and mechanical engineering,” said Aaron Birt ’17, CEO of Solvus Global, a subcontractor on the grant. “This is one of those rare opportunities that demonstrates the breadth of technical expertise required to deliver a solution for manufacturing at the point of need anywhere on Earth, the moon, or beyond. That proposition shows the genuine ability of this team to imagine and deliver solutions of tomorrow.”
“VALIS was founded on the mission of delivering enabling technology to maximize the recovery of valuable materials for future generations,” said Emily Molstad ’19, MS ’19, co-founder and CEO of VALIS Insights, a grant subcontractor. “We see the recycling industry becoming increasingly vertically integrated as raw material producers and manufacturers aim to secure a reliable supply of scrap material and increase recycled content to drive down costs. The technology being developed through this program will unlock new levels of upcycling capabilities not only in remote, resource-restricted locations, but across the recycling value chain with the potential to strengthen domestic manufacturing capabilities.”
At WPI, in addition to Cote, assistant research professor Kyle Tsaknopoulos will work on the project with several PhD, master’s, and undergraduate students. The project is expected to be completed in November 2027.
New 3D printing method enables complex designs and creates less waste
MIT engineers developed a technique for making intricate structures with supports that can be dissolved and reused instead of thrown away.
Massachusetts Institute of Technology
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The researchers applied the new method to print complex structures, including functional gear trains, intricate lattices, and a dental implant.
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Credit: Courtesy of Nicholas Diaco, Carl Thrasher, Max Hughes, Kevin Zhou, Michael Durso, Saechow Yap, Robert Macfarlane, and A. John Hart
Hearing aids, mouth guards, dental implants, and other highly tailored structures are often products of 3D printing. These structures are typically made via vat photopolymerization — a form of 3D printing that uses patterns of light to shape and solidify a resin, one layer at a time.
The process also involves printing structural supports from the same material to hold the product in place as it’s printed. Once a product is fully formed, the supports are removed manually and typically thrown out as unusable waste.
MIT engineers have found a way to bypass this last finishing step, in a way that could significantly speed up the 3D-printing process. They developed a resin that turns into two different kinds of solids, depending on the type of light that shines on it: Ultraviolet light cures the resin into an highly resilient solid, while visible light turns the same resin into a solid that is easily dissolvable in certain solvents.
The team exposed the new resin simultaneously to patterns of UV light to form a sturdy structure, as well as patterns of visible light to form the structure’s supports. Instead of having to carefully break away the supports, they simply dipped the printed material into solution that dissolved the supports away, revealing the sturdy, UV-printed part.
The supports can dissolve in a variety of food-safe solutions, including baby oil. Interestingly, the supports could even dissolve in the main liquid ingredient of the original resin, like a cube of ice in water. This means that the material used to print structural supports could be continuously recycled: Once a printed structure’s supporting material dissolves, that mixture can be blended directly back into fresh resin and used to print the next set of parts — along with their dissolvable supports.
The researchers applied the new method to print complex structures, including functional gear trains and intricate lattices.
“You can now print — in a single print — multipart, functional assemblies with moving or interlocking parts, and you can basically wash away the supports,” says graduate student Nicholas Diaco. “Instead of throwing out this material, you can recycle it on site and generate a lot less waste. That’s the ultimate hope.”
He and his colleagues report the details of the new method in a paper appearing in Advanced Materials Technologies. The MIT study’s co-authors include Carl Thrasher, Max Hughes, Kevin Zhou, Michael Durso, Saechow Yap, Professor Robert Macfarlane, and Professor A. John Hart, head of MIT’s Department of Mechanical Engineering.
Waste removal
Conventional vat photopolymerization (VP) begins with a 3D computer model of a structure to be printed — for instance, of two interlocking gears. Along with the gears themselves, the model includes small support structures around, under, and between the gears to keep every feature in place as the part is printed. This computer model is then sliced into many digital layers that are sent to a VP printer for printing.
A standard VP printer includes a small vat of liquid resin that sits over a light source. Each slice of the model is translated into a matching pattern of light that is projected onto the liquid resin, which solidifies into the same pattern. Layer by layer, a solid, light-printed version of the model’s gears and supports forms on the build platform. When printing is finished, the platform lifts the completed part above the resin bath. Once excess resin is washed away, a person can go in by hand to remove the intermediary supports, usually by clipping and filing, and the support material is ultimately thrown away.
“For the most part, these supports end up generating a lot of waste,” Diaco says.
Print and dip
Diaco and the team looked for a way to simplify and speed up the removal of printed supports and, ideally, recycle them in the process. They came up with a general concept for a resin that, depending on the type of light that it is exposed to, can take on one of two phases: a resilient phase that would form the desired 3D structure and a secondary phase that would function as a supporting material but also be easily dissolved away.
After working out some chemistry, the team found they could make such a two-phase resin by mixing two commercially available monomers, the chemical building blocks that are found in many types of plastic. When ultraviolet light shines on the mixture, the monomers link together into a tightly interconnected network, forming a tough solid that resists dissolution. When the same mixture is exposed to visible light, the same monomers still cure, but at the molecular scale the resulting monomer strands remain separate from one another. This solid can quickly dissolve when placed in certain solutions.
In benchtop tests with small vials of the new resin, the researchers found the material did transform into both the insoluble and soluble forms in response to ultraviolet and visible light, respectively. But when they moved to a 3D printer with LEDs dimmer than the benchtop setup, the UV-cured material fell apart in solution. The weaker light only partially linked the monomer strands, leaving them too loosely tangled to hold the structure together.
Diaco and his colleagues found that adding a small amount of a third “bridging” monomer could link the two original monomers together under UV light, knitting them into a much sturdier framework. This fix enabled the researchers to simultaneously print resilient 3D structures and dissolvable supports using timed pulses of UV and visible light in one run.
The team applied the new method to print a variety of intricate structures, including interlocking gears, intricate lattices, a ball within a square frame, and, for fun, a small dinosaur encased in an egg-shaped support that dissolved away when dipped in solution.
“With all these structures, you need a lattice of supports inside and out while printing,” Diaco says. “Removing those supports normally requires careful, manual removal. This shows we can print multipart assemblies with a lot of moving parts, and detailed, personalized products like hearing aids and dental implants, in a way that’s fast and sustainable.”
“We’ll continue studying the limits of this process, and we want to develop additional resins with this wavelength-selective behavior and mechanical properties necessary for durable products,” says professor of mechanical engineering John Hart. “Along with automated part handling and closed-loop reuse of the dissolved resin, this is an exciting path to resource-efficient and cost-effective polymer 3D printing at scale.”
This research was supported, in part, by the Center for Perceptual and Interactive Intelligence (InnoHK) in Hong Kong, the U.S. National Science Foundation, the U.S. Office of Naval Research, and the U.S. Army Research Office.
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Written by Jennifer Chu, MIT News
Paper: “Dual-Wavelength Vat Photopolymerization with Dissolvable, Recyclable Support Structures”
https://advanced.onlinelibrary.wiley.com/doi/10.1002/admt.202500650
Journal
Advanced Materials Technologies
Article Title
“Dual-Wavelength Vat Photopolymerization with Dissolvable, Recyclable Support Structures”
