Decoupling resolution and throughput: How to achieve faster build rates through Large Area LPBF

 

Metal AM has not yet gained significant market share in high-volume manufacturing because of the current limitation to the speed of the process, which strongly affects the production price per piece that can be achieved. The speed at which parts can be built is limited to how fast material can be melted and solidified into the underlying part. 

 

But high speed without high resolution is not a powerful equation. With existing metal AM processes, the two are often at odds. Decoupling them means production scale with precision. 

 

This presentation will include the following:

How to achieve faster build rates by evolving from a serial printing process to a parallel process
Why increasing build speed with high resolution unlocks new applications for AM
New frontier opportunities

Many processes in both nature and industry occur at the microscale and involve complex multiphase interfaces. Most microporous media, both natural and man-made, tend to be stochastic and therefore difficult to predict or control reliably. On the other hand, conventional microfluidic devices are often limited to enclosed channels and planar geometries, which hinders their usefulness in multiphase reaction or transport processes involving gas phases. We present a novel platform based on capillary fluid flow in ordered three-dimensional open-cell lattices [1]. Using deterministic cell and lattice design, combined with additive manufacturing methods that provide access to length scales < 100 um, we can fabricate complex 3D structures with tuned porosity and advanced functionalities. This approach enables selective placement and direction of liquid flow or gas flow into predetermined continuous paths through the structure, as well as optimizing for the occurrence of gas-liquid, liquid-liquid, or gas-liquid-solid interfaces. We demonstrate the application of cellular fluidics for processes such as transpiration cooling, CO2 capture, selective patterning, and biological cell culture.
 

***This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 within the LDRD program 19-SI-005. LLNL-ABS-778327. 

[1] Dudukovic, Nikola A., et al. "Cellular fluidics." Nature 595.7865 (2021): 58-65.

3D printing offers enormous flexibility in fabrication of polymer objects with complex geometries. However, it is not suitable for fabricating large polymer structures with geometrical features at the sub-micrometer scale. Porous structure at the sub-micrometer scale can render macroscopic objects with unique properties, including similarities with biological interfaces, permeability, superhydrophobicity and extremely large surface area, imperative inter alia for adsorption, separation, sensing or biomedical applications. In my presentation, I will demonstrate a method combining advantages of 3D printing and polymerization-induced phase separation, which enables formation of 3D polymer structures with controllable inherent porosity at the sub-micrometer scale. 3D polymer structures of highly complex geometries and spatially controlled pore sizes from 10 nm to 1000 µm can be fabricated using this method. Produced hierarchical polymers combining nanoporosity with micrometer-sized pores demonstrate improved adsorption performance due to better pore accessibility and favore cell adhesion and growth for 3D cell culture. The developed method extends the scope of applications of 3D printing to hierarchical inherently porous 3D objects as well as superhydrophobic 3D objects, making them available for a wide variety of applications.

3D printing has been historically relegated to fabricating conceptual models and prototypes; however, increasingly, research is now focusing on fabricating functional end-use products.  As patents for 3D printing expire, new low-cost desktop systems are being adopted more widely and this trend is leading to a diversity of new products, processes and available materials. However, currently the technology is generally confined to fabricating single material static structures. For additively manufactured products to be economically meaningful, additional functionalities are required to be incorporated in terms of electronic, electromechanical, electromagnetic, thermodynamic, chemical and optical content.  By interrupting the 3D printing and employing complementary manufacturing processes, additional functional content can be included in mass-customized structures. This presentation will review work in multi-process 3D printing for creating structures with consumer-anatomy-specific wearable electronics, electromechanical actuation, electromagnetics, propulsion, embedded sensors in soft tooling and including metal and ceramic structures.

 

Other projects to be presented include stereovision process monitoring of powder bed fusion, 3D printed smart molds for sand casting, complex ceramic lattices for electromagnetic lenses, elastomeric lattices for the athletic gear, computation geometry and complexity theory for 3D printing, thermography stereovision for directed energy deposition.

The implementation of additive manufacturing techniques to produce critical spaceflight systems is well underway.  These technologies will be a key contributor to developing both launch vehicles and spacecraft that will play a crucial role in delivering the first woman and the next man to the surface of the moon by 2025.  In 2021 NASA released NASA-STD-6030 “Additive Manufacturing Requirements for Spaceflight Systems” design to create certification and qualification strategies for mature technologies for both metallic and non-metallic materials. 

The fracture control methodologies that NASA uses for the qualification of critical spaceflight hardware is heavily reliant on a full understanding of the design, analysis, testing, inspection and tracking of hardware.  New advances in additive manufacturing technologies have quickly created unique challenges that are not captured in the current NASA-STD-6030 framework.  Examples include the use of multiple lasers, adaptive technologies and components that cannot be inspection using quantitative nondestructive evaluation.  To adapt, NASA has begun to produce explore the adaptation of Probabilistic Damage Tolerance Approaches (PDTA).  This approach includes the development of computational modeling, understanding the “effect of defects” and the implementation of in-situ monitoring and inspection techniques.

We review our recent progress on 3D and 4D laser printing on the micrometer and nanometer scale. This includes light-responsive metamaterial architectures based on liquid-crystal elastomers, the local director of which we align in situ by means of quasi-static electric fields during the 3D multi-photon printing process. Furthermore, we introduce in-situ diagnostics by means of optical-coherence tomography (joint work with ZEISS). Finally, we report on our efforts on using two-step absorption instead of two-photon absorption. Focus-scanning 3D printing based on one-color two-step absorption allows for democratizing 3D nanoprinting (joint work with Nanoscribe). Projection-based light-sheet 3D printing using two-color two-step absorption supports printing rates approaching 107 voxels/s at voxel volumes below 1 µm3.

Synopsis: I will show how we can use high resolution 3D printing techniques, such as projection micro stereolithography and two photon polymerisation, to probe the biological response of cells on architectured surfaces, potentially leading to the development of new implants that can promote healing and regeneration of tissue.