2024-10-04 15:35:44
By using the 3D extrusion technology of the CEM process, AIM3D has developed a Voxelfill strategy that overcomes the limitations of FFF printing and many other techniques, especially the inhomogeneous mechanical properties. Tests show that the patented Voxelfill results in strengths in all directions that are close to those of injection molded parts.
“We believe in our CEM technology now more than ever. 3D pellet printers offer the unique opportunity to very cost-effectively match the properties of conventionally manufactured parts with an additive manufacturing strategy. With the Voxelfill strategy, 3D printing now approaches the mechanical strengths of conventional injection molding,” says Clemens Lieberwirth, CTO of the German printer manufacturer from Rostock.
Multimaterialen printers
AIM3D builds 3D pellet printers. The Composite Extrusion Modeling (CEM) technology combines powder injection molding (PIM) with additive manufacturing. Compared to FFF printers, the build speed is a factor of 2 to 20 higher. And CEM technology can be used for polymers, metals and ceramic materials. With these last two materials, the green parts that AIM3D printers print only acquire their final properties after sintering. The three materials can possibly be combined in one workpiece.
Brick bond with fiber filling
Gamechanger regarding the mechanical strength of 3D printed pieces
80% of strength of injection molded products
Tests with different materials now show that with this strategy in the Z direction you achieve much higher tensile strengths than the 50% that is normal, depending on the material. With this Voxelfill strategy, AIM3D prints tensile strengths in the printing direction that are 80% compared to those of injection molded products of the same material. The goal is to ultimately reach 100%. The potential is there, according to the manufacturer. It is thought that virtually isotropic properties can be printed in all directions by positioning fibers in the printing direction. This goes hand in hand with higher productivity. Clemens Lieberwirth, CTO of AIM 3D: “This makes Voxelfill a game changer with regard to the mechanical strength of 3D components.”
Test with PETG-1000 from Polymaker
As part of the AIM3D feasibility study, the strength (MPa) and elongation (%) were measured in Polycore PETG-1000 from Polymaker). The test specimens in three variants show a ductile stress-strain curve in XY orientation, which is typical for an unfilled plastic. At 52.83 MPa, the tensile strength is even slightly higher than the value from the material information sheet (50 +/-1.1 MPa) for injection molding. A comparison between the conventionally printed test pieces and the Voxelfill test pieces shows that the use of Voxelfill results in twice as high tensile strength: from 20 MPa for the conventionally printed test pieces to 40 MPa for the Voxelfill test pieces. In comparison, the strength of the horizontally printed samples was 53 MPa. In summary: The anisotropy is 70% for the conventionally printed samples and only 23% for the Voxelfill test pieces.
Printing with filled plastics
To measure the strength in the Z direction when using filled material, AIM3D printed with PETG GF30 from Polymaker at an extrusion temperature of 270 degrees C. The tensile strength with the infill oriented in the tensile direction was the highest at 72.4 MPa. However, this corresponds to an earlier fictional case, as this would not occur in a real injection molded part, where the fiber distribution depends on the geometry of the part and the number and orientation of the injection points. In comparison, the horizontal tensile samples with an infill orientation of +/- 45° reached 50.1 MPa. A comparison of the determined values for the tensile strengths shows a homogeneity of strength of 81% for Voxelfill compared to the +/-45° printed reference samples and 56% compared to the aligned reference samples.
Ultimate 9085
Finally, AIM3D also printed with ULTEM 9085. This was done with the ExAM 510 3D printer. This now prints a maximum of 150 cm3 per hour; AIM3D wants to increase this to 300 to 600 cm3 per hour in the coming years. With the PEI material Sabic ULTEM 9085, 3D pellet printing now achieves component properties that come close to the classic injection molding process. Compared to FDM printers, a 100% higher elongation at break is achieved. This therefore opens up the possibility of using PEI in application areas in the automotive industry, aerospace, rail vehicles and defense technology.
Lots of potential
AIM3D sees a lot of potential for this Voxell strategy. This is partly because the volume spaces are only 3D printed and filled in parts where strength is really needed. This saves material and printing time and makes components lighter, while the strength is higher. In the horizontal plane, the CEM process already offers very good options for controlling the orientation of the fibers. By injecting the material into the volume chambers (filling the voxels), the 3D part also acquires fibers aligned along the Z-axis, further improving its mechanical properties. Finally, Clemens Lieberwirth says: “Of course, the Voxelfill process is particularly suitable for 3D printing of plastics and fiber-filled plastics, but it is also suitable for 3D printing of metal and ceramic parts using the CEM process. Overall, the main benefits are higher build speed and cross-layer filling.”
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#solution #strength #direction #printing
