The mechanical strength of extrusion-based printed components is often greatly reduced in the build direction (z-direction) compared to the in-plane strength due to poor bonding between successively deposited layers. This is especially true when depositing fiber-reinforced materials or larger print areas with long layer times. The Big Area Additive Manufacturing (BAAM) system has demonstrated up to a 75-90% reduction in strength in the z-direction when printing with carbon fiber reinforced materials. Therefore, a patent-pending approach has been developed that enables continuous material to be deposited in the z-direction that spans multiple layers. The “z-pinning” approach utilizes intentionally aligned voids across multiple (n) layers. During the deposition on layer (n+1), the deposition nozzle dwells over the void space and extrudes molten material to fill the void. A variation on this approach utilizes a high aspect ratio nozzle (longer & thinner) to penetrate the void space and deposit material during retraction. Several z-pinning deposition variations will be presented along with mechanical test results to demonstrate improved performance.
- Describe the novel z-pinning approach.
- Understand the fundamentals of the z-pinning mechanism and the link to improved mechanical properties.