Cheetah Filament Helps Researchers Achieve the World’s Fastest 3D-Printed Parts

Application: Projectile acceleration component
Material used: Cheetah^® 3D Printer Filament
Industry: Industrial Manufacturing, Research

Southwest Research Institute (SwRI), a non-profit R&D institution that provides independent services to government and industry clients, in conjunction with Digital to Definitive, LLC (DtD) an Austin, Texas-based 3D-Printing and Consulting company, recently announced that they have successfully employed fused filament fabrication (FFF) to aid in the launch of individual sub-caliber 1 cm3 metallic cubes from a 20mm smooth-bore laboratory cannon at velocities ranging from 1000 ft/sec to 6520 ft/sec.

Tests such as these are used to simulate the high-speed impact of metal fragments under laboratory conditions. For each test, the interface between the bore of the cannon and the metallic cube projectile was provided by a two-part 3D-printed component called a “sabot” (i.e., French for shoe) that travels through the bore along with the projectile during the launch event.

For a successful launch, the sabot must perform several functions in unison. It must provide a gas seal between the extremely hot, high-pressure propellant gas and the bore of the cannon as the sabot travels down-bore under high acceleration.

Simultaneously, the sabot must protect the projectile and center it laterally in the bore during launch. After launch, the sabot must then separate cleanly from the projectile and move away from the shot line so as to not interfere with the flight and impact of the projectile. In total, more than 300 successful test launches using FFF sabots have been conducted to date.

Of the company’s recent success, SwRI Program Director Dr. Christopher J. Freitas said, “Until now, we knew that 3D printing could provide parts useful for items such as jigs and fixtures; but no one would have guessed that FFF-manufactured parts would survive and function in such an extreme environment. The FFF process allowed many prototype sabot designs and materials to be tested rapidly, which saved us a tremendous amount of time and money over conventionally manufacturing the sabots. We have since utilized 3D-printed sabots for launching various projectile shapes of interest and we intend to adapt the technology to other laboratory launchers at the institute in the near future.”

“Cheetah is a breeze to print with once the print settings are dialed in. The sabots are able to be taken directly from the printer to the laboratory without any post-processing. It’s a great material to work with and is perfect for this demanding application.”

Further details of the tests include:

• A two-part loading was utilized: the sabot and projectile were first loaded as a unit into the bore of the launcher, followed by a metallic cartridge case filled with propellant. The rear of the sabot was subjected directly to the burning gas of the propellant
• At the highest velocities attained the sabot was subjected to over 30,000 psi and temperatures in excess of 2500°C
• Although many FFF materials were examined, including PLA, PLA+, PETG, and various Nylon blends, the only fully successful material to survive the severe test environment was NinjaTek Cheetah TPU.
• The unique material properties of Cheetah were essential to success: Elongation at Break of 580%, Toughness of 17000 in·lbf/in3, Impact Strength of 9.1 ft·lbf/in2, and a Hardness of 95A. The relatively low durometer allowed the sabots to be manufactured slightly oversize and be tightly compressed in the bore when loaded, which helped to form the high-pressure gas seal at the base of the sabot.

About SwRI: We are R&D problem solvers providing independent, premier services to government and industry clients. Our multidisciplinary nature allows us to rapidly assemble diverse teams to tackle problems from multiple directions. We push the boundaries of science and technology to develop innovative solutions that advance the state of the art and improve people’s understanding in science and engineering applications. Operating as a nonprofit since our 1947 inception, we work in the public’s best interest and toward the betterment of mankind. And as a contract R&D organization, we are here when you need us. Learn more about how to WORK WITH US.

About DtD: With over 30 years’ experience in the Aerospace Defense Industry, DtD, a limited liability company founded by Darrel R. Barnette, Principal, provides engineering and additive manufacturing services to US government, university, and industry clients. Activities include educating clients in the area of application of additive manufacturing processes, acting as a service provider for engineered additive-manufactured parts, and designing and producing prototype functioning and final parts in multiple and diverse fields such as medical, sporting and outdoors, aerospace, and oil and gas industries.