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Manufacturing—Layering on the strength

The Z-pinning technique is used to insert reinforcing fibers along the Z-direction of continuous fiber-reinforced plastics. ORNL researchers used PLA to print a small wall, demonstrating that Z-pinning produces mechanically uniform properties when measured in any direction. Credit: Tyler Smith/Oak Ridge National Laboratory, U.S. Dept. of Energy  

A team including Oak Ridge National Laboratory and University of Tennessee researchers demonstrated a novel 3D printing approach called Z-pinning that can increase the material’s strength and toughness by more than three and a half times compared to conventional additive manufacturing processes. They demonstrated Z-pinning with polylactic acid, or PLA, and carbon fiber-reinforced PLA in a 3D printer designed for thermoplastic materials. With conventional 3D printing, the layer-by-layer building up of PLA materials can cause weaknesses between layers. Z-pinning allows continuous material to be deposited across multiple layers within the volume of the part. “The conventional layering approach can cause the strength of the material to decrease as much as 75%,” ORNL’s Vlastimil Kunc said. “The PLA sample with Z-pinning demonstrated uniform mechanical properties when measured in any direction. This technique can be used on any existing 3D printer.” The team’s results were published in the journal Additive Manufacturing.