It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Monday, April 08, 2024
This 3D printer can figure out how to print with an unknown material
The advance could help make 3D printing more sustainable, enabling printing with renewable or recyclable materials that are difficult to characterize.
NEWS RELEASE MASSACHUSETTS INSTITUTE OF TECHNOLOGY
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RESEARCHERS DEVELOPED A 3D PRINTER THAT CAN AUTOMATICALLY IDENTIFY THE PARAMETERS OF AN UNKNOWN MATERIAL ON ITS OWN.
CREDIT: COURTESY OF NEIL GERSHENFELD, JAKE READ, ET AL
While 3D printing has exploded in popularity, many of the plastic materials these printers use to create objects cannot be easily recycled. While new sustainable materials are emerging for use in 3D printing, they remain difficult to adopt because 3D printer settings need to be adjusted for each material, a process generally done by hand.
To print a new material from scratch, one must typically set up to 100 parameters in software that controls how the printer will extrude the material as it fabricates an object. Commonly used materials, like mass-manufactured polymers, have established sets of parameters that were perfected through tedious, trial-and-error processes.
But the properties of renewable and recyclable materials can fluctuate widely based on their composition, so fixed parameter sets are nearly impossible to create. In this case, users must come up with all these parameters by hand.
Researchers tackled this problem by developing a 3D printer that can automatically identify the parameters of an unknown material on its own.
A collaborative team from MIT’s Center for Bits and Atoms (CBA), the U.S. National Institute of Standards and Technology (NIST), and the National Center for Scientific Research in Greece (Demokritos) modified the extruder, the “heart” of a 3D printer, so it can measure the forces and flow of a material.
These data, gathered through a 20-minute test, are fed into a mathematical function that is used to automatically generate printing parameters. These parameters can be entered into off-the-shelf 3D printing software and used to print with a never-before-seen material.
The automatically generated parameters can replace about half of the parameters that typically must be tuned by hand. In a series of test prints with unique materials, including several renewable materials, the researchers showed that their method can consistently produce viable parameters.
This research could help to reduce the environmental impact of additive manufacturing, which typically relies on nonrecyclable polymers and resins derived from fossil fuels.
“In this paper, we demonstrate a method that can take all these interesting materials that are bio-based and made from various sustainable sources and show that the printer can figure out by itself how to print those materials. The goal is to make 3D printing more sustainable,” says senior author Neil Gershenfeld, who leads CBA.
His co-authors include first author Jake Read a graduate student in the CBA who led the printer development; Jonathan Seppala, a chemical engineer in the Materials Science and Engineering Division of NIST; Filippos Tourlomousis, a former CBA postdoc who now heads the Autonomous Science Lab at Demokritos; James Warren, who leads the Materials Genome Program at NIST; and Nicole Bakker, a research assistant at CBA. The research is published in the journal Integrating Materials and Manufacturing Innovation.
Shifting material properties
In fused filament fabrication (FFF), which is often used in rapid prototyping, molten polymers are extruded through a heated nozzle layer-by-layer to build a part. Software, called a slicer, provides instructions to the machine, but the slicer must be configured to work with a particular material.
Using renewable or recycled materials in an FFF 3D printer is especially challenging because there are so many variables that affect the material properties.
For instance, a bio-based polymer or resin might be composed of different mixes of plants based on the season. The properties of recycled materials also vary widely based on what is available to recycle.
“In ‘Back to the Future,’ there is a ‘Mr. Fusion’ blender where Doc just throws whatever he has into the blender and it works ]as a power source for the DeLorean time machine]. That is the same idea here. Ideally, with plastics recycling, you could just shred what you have and print with it. But, with current feed-forward systems, that won’t work because if your filament changes significantly during the print, everything would break,” Read says.
To overcome these challenges, the researchers developed a 3D printer and workflow to automatically identify viable process parameters for any unknown material.
They started with a 3D printer their lab had previously developed that can capture data and provide feedback as it operates. The researchers added three instruments to the machine’s extruder that take measurements which are used to calculate parameters.
A load cell measures the pressure being exerted on the printing filament, while a feed rate sensor measures the thickness of the filament and the actual rate at which it is being fed through the printer.
“This fusion of measurement, modeling, and manufacturing is at the heart of the collaboration between NIST and CBA, as we work develop what we’ve termed ‘computational metrology,’” says Warren.
These measurements can be used to calculate the two most important, yet difficult to determine, printing parameters: flow rate and temperature. Nearly half of all print settings in standard software are related to these two parameters.
Deriving a dataset
Once they had the new instruments in place, the researchers developed a 20-minute test that generates a series of temperature and pressure readings at different flow rates. Essentially, the test involves setting the print nozzle at its hottest temperature, flowing the material through at a fixed rate, and then turning the heater off.
“It was really difficult to figure out how to make that test work. Trying to find the limits of the extruder means that you are going to break the extruder pretty often while you are testing it. The notion of turning the heater off and just passively taking measurements was the ‘aha’ moment,” says Read.
These data are entered into a function that automatically generates real parameters for the material and machine configuration, based on relative temperature and pressure inputs. The user can then enter those parameters into 3D printing software and generate instructions for the printer.
In experiments with six different materials, several of which were bio-based, the method automatically generated viable parameters that consistently led to successful prints of a complex object.
Moving forward, the researchers plan to integrate this process with 3D printing software so parameters don’t need to be entered manually. In addition, they want to enhance their workflow by incorporating a thermodynamic model of the hot end, which is the part of the printer that melts the filament.
This collaboration is now more broadly developing computational metrology, in which the output of a measurement is a predictive model rather than just a parameter. The researchers will be applying this in other areas of advanced manufacturing, as well as in expanding access to metrology.
This research is supported, in part, by the National Institute of Standards and Technology and the Center for Bits and Atoms Consortia.
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Written by Adam Zewe, MIT News
Paper: “Online Measurement for Parameter Discovery in Fused Filament Fabrication”
“Online Measurement for Parameter Discovery in Fused Filament Fabrication”
Proof-of-principle demonstration of 3-D magnetic recording
Possibility of ultra-high density hard disk drives with areal densities exceeding 10 Tbit/in² using multi-level magnetic recording
NATIONAL INSTITUTE FOR MATERIALS SCIENCE, JAPAN
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SCHEMATIC VIEW OF (TOP) CURRENTLY USED HAMR AND (BOTTOM) THREE-DIMENSIONAL MAGNETIC RECORDING SYSTEMS. IN THE THREE-DIMENSIONAL MAGNETIC RECORDING SYSTEM, THE CURIE TEMPERATURE OF EACH RECORDING LAYER DIFFERS BY ABOUT 100 K AND DATA ARE WRITTEN TO EACH LAYER BY ADJUSTING THE LASER POWER.
CREDIT: YUKIKO TAKAHASHI NIMS, THOMAS CHANG SEAGATE TECHNOLOGY, SIMON GREAVES TOHOKU UNIVERSITY
1. Research groups from NIMS, Seagate Technology, and Tohoku University have made a breakthrough in the field of hard disk drives (HDD) by demonstrating the feasibility of multi-level recording using a three-dimensional magnetic recording medium to store digital information. The research groups have shown that this technology can be used to increase the storage capacity of HDDs, which could lead to more efficient and cost-effective data storage solutions in the future.
2. Data centers are increasingly storing vast amounts of data on hard disk drives (HDDs) that use perpendicular magnetic recording (PMR) to store information at areal densities of around 1.5 Tbit/in². However, to transition to higher areal densities, a high anisotropy magnetic recording medium consisting of FePt grains combined with heat-assisted laser writing is required. This method, known as heat-assisted magnetic recording (HAMR), is capable of sustaining areal recording densities of up to 10 Tbit/in². Furthermore, densities of larger than 10 Tbit/in² are possible based on a new principle demonstrated by storing multiple recording levels of 3 or 4 compared with the binary level used in HDD technology.
3. In this study, we succeeded in arranging the FePt recording layers three dimensionally, by fabricating lattice-matched, FePt/Ru/FePt multilayer films, with Ru as a spacer layer. Measurements of the magnetization show the two FePt layers have different Curie temperatures. This means that three-dimensional recording becomes possible by adjusting the laser power when writing. In addition, we have demonstrated the principle of 3D recording through recording simulations, using a media model that mimics the microstructure and magnetic properties of the fabricated media.
4. The three-dimensional magnetic recording method can increase recording capacity by stacking recording layers in three dimensions. This means that more digital information can be stored with fewer HDDs, leading to energy savings for data centers. In the future, we plan to develop processes to reduce the size of FePt grains, to improve the orientation and magnetic anisotropy, and to stack more FePt layers to realize a media structure suitable for practical use as a high-density HDD.
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5. This research was conducted by Dr. P. Tozman, Distinguished Researcher, and Dr. Yukiko Takahashi, Group Leader of NIMS Center for Magnetic and Spintronics Materials Research, Dr. T.Y. Chang, Researcher at Seagate Technology, and Prof. S.J. Greaves of Tohoku University. This work was supported by Japan Science and Technology Agency (JST) Strategic Basic Research Programs (CREST) "Integrated Devices and Systems Utilizing Information Carriers" JPMJCR22C3.
6. This research was published in Acta Materialia on March 24, 2024.
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