A very tough, resilient, and lightweight 3D printing composite filament called FilaOne Gray can hold more than 1,000 times its own weight. The secret? Carbon nanotube reinforcement. Don't believe it? Check out the extremely short but impressive "torture test" video below. But this wonder material does more.
According to Avante Technology president Bob Zollo, ASTM testing showed that FilaOne Gray has a high flexural modulus and tensile strength, making it 48% stronger than ABS. A technical data sheet says that FilaOne Gray's flexural modulus is 217,411 psi, closer to that of polycarbonate (PC), versus ABS at 149,539 psi. Zollo also said that, at 0.86 grams/cubic cm when printed at 100% infill, the engineering-grade material is lighter than either ABS or polycarbonate.
It's also highly resilient. "As the video shows, the composite can withstand massive deformation and stress without cracking or crazing," Zollo told Design News. "And it holds over 1,400 times its own weight. It provides perhaps the highest strength-to-weigh ratio of any filament available today."
In a tensile strength test (ASTM 638-02A), FilaOne Gray demonstrated a yield of 8,373 psi and 0.54%, and break of 641,848 psi and 22.86%. The test used test bars printed at 100% infill, and printed along the X-Y axis of the test bar, that is, parallel with the long dimension and with the wide side down. Flexural modulus tests (ASTM 790-02) used similar test bars printed the same way.
The technical data sheet containing this data notes that, "ASTM test methods specify molded test bars or bars cut from plastic sheet. There are no ASTM specifications for 3D printing test bars. Research by a variety of third parties indicates that the printing strategy and infill pattern used may have significant impact on mechanical properties. Care should be taken when comparing these values with third-party tests." It also notes that Avante Technology has "selected the 'worst case' printing strategy of printing along the X-Y axis."
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Zollo said there are good reasons for this caution. Research his company has done with university labs showed that the mechanical properties of test bars made with 3D-printed filament can vary a lot, depending on their print orientation when produced with a 3D printer. "In testing on the same printer using the same print height and orientation, and using 100% infill, if you print the piece on the flat of the test bed, the X-Y axis, you'll get one set of test results," he said. "If you rotate it and print it on its edge, you'll get a different set of test results. And if you print it on end, you'll get a third set. Between one test bar print orientation and another, with all else the same, test results of tensile and flexural modulus will vary by plus or minus 30%. The only difference is in the test bar's print orientation."
The secret to FilaOne Gray's outstanding mechanical properties is its carbon nanotube reinforcement. A proprietary type of carbon nanotubes (CNTs) have been highly dispersed throughout the filament. The CNTs "act like tiny steel rebars in concrete," said Zollo. "They stiffen the composite, but provide for recovery after deformation," stretching instead of cracking, crazing, or breaking. This makes it excellent for living hinge applications, as well as outdoor, marine, and aviation uses. The filament is also hyrophobic and resistant to UV, mild acids, and caustic chemicals.
Ann R. Thryft is senior technical editor, materials & assembly, for Design News. She's been writing about manufacturing- and electronics-related technologies for 29 years, covering manufacturing materials & processes, alternative energy, and robotics. In the past, she's also written about machine vision and all kinds of communications.