Process Planning for Concurrent Multi-nozzle 3D Printing

Additive manufacturing (AM) processes possess excellent capabilities for manufacturing complex designs as single uniform parts with optimum material utilization. However, the processes are still not widely used in industry to make large parts. The main reason for this slow adoption is the low material deposition rate during printing. Increasing the material deposition rate by increasing the layer thickness or utilizing larger diameter nozzles results in deterioration of the surface quality of the part. This is known as the “staircase effect”; thus there is a trade-off between the print time and the surface finish of a part. A majority of the research efforts focused on minimizing this trade-off aim to minimize the print time by optimizing the layer thickness based on the evaluation of local geometry of the part. Another approach adopted in minimizing this trade-off is to utilize multiple nozzles concurrently for increasing the material deposition rate. The processes leveraging this approach use independent nozzles with relative motion between them and are seen to be more suitable for parts with a large footprint in the X-Y plane. This thesis further explores this direction of research by utilizing multiple nozzles, mounted on the same print-head, for concurrent printing to increase the deposition rate. The algorithm developed here requires a rotational axis. A 4-axis multi-nozzle toolpath generator, a G-code simulator and a proof-of-concept machine were therefore developed as part of this thesis

Automated Process Planning for Embossing and Functionally Grading Materials via Site-Specific Control in Large-Format Metal-Based Additive Manufacturing

The potential for site-specific, process-parameter control is an attribute of additive manufacturing (AM) that makes it highly attractive as a manufacturing process. The research interest in the functionally grading material properties of numerous AM processes has been high for years. However, one of the issues that slows developmental progress in this area is process planning. It is not uncommon for manual programming methods and bespoke solutions to be utilized for site-specific control efforts. This article presents the development of slicing software that contains a fully automated process planning approach for enabling through-thickness, process-parameter control for a range of AM processes. The technique includes the use of parent and child geometries for controlling the locations of site-specific parameters, which are overlayed onto unmodified toolpaths, i.e., a vector-based planning approach is used in which additional information, such as melt pool size for large-scale metal AM processes, is assigned to the vectors. This technique has the potential for macro- and micro-structural modifications to printed objects. A proof-of-principle experiment is highlighted in which this technique was used to generate dynamic bead geometries that were deposited to induce a novel surface embossing effect, and additional software examples are presented that highlight software support for more complex objects

Modelling of Microstructure Evolution in Wire-Based Laser Direct Energy Deposition with Ti-6Al-4V

Over the past years, wire-based direct energy deposition (DED) has been transitioning from rapid prototyping to the production of end-use part and mass production. However, a wide market penetration of the DED has not happened yet. The difficulties for wide-scale market adoption to critical structural components are related to the development cost for process optimization and for manufacturing of high-quality parts. For metallic components, the process conditions (e.g., power, speed, tool path) control the material and mechanical properties/performance of the printed part. The thermal history strongly determines the phase fraction, morphology, growth pattern, size of microstructure, and nature of defects. Thus, in this study, we: 1) developed a thermal simulation using finite element method, 2) experimentally measured thermal histories from a U-shaped part with four tool paths of horizontal, vertical, raster, and contour to calibrate and validate the thermal model, and 3) investigated the effect of thermal history on microstructure evolution and quantified the microstructural variation during the printing process.Mechanical Engineerin

SkyBAAM Large-Scale Fieldable Deposition Platform System Architecture

Oak Ridge National Laboratory (ORNL) is currently developing a concrete deposition system for infrastructure-scale printed objects. This system, called SkyBAAM, uses a cable driven motion platform to manipulate the print head. This work focuses on the general aspects of the system architecture, including arrangement of the cable driven platform, general high-level control methodology, and system accuracy, along with concrete deposition methods. Results and demonstration prints will be shown.Mechanical Engineerin

Large-Scale Thermoset Pick and Place Testing and Implementation

Oak Ridge National Laboratory is developing the first commercially available medium to large-scale thermoset additive manufacturing (AM) system with Magnum Venus Products (MVP). This 3D printer is capable of fabricating large-scale thermoset components at room temperature with a build volume of 16’ x 8’ x 42’’. The thermoset extrusion process uses irreversible exothermic chemical reactions to form a cross-linked SRO\PHU ௗ3ULQWLQJWKHUPRVHWVDWVXFKODUJHVFDOHVZLWKKLJKO\FXVWRPL]DEOHPDWHULDOVDWURRP temperature provides huge opportunities for complex and smart tooling applications. Integrating a pick and place actuator into this system will allow for the placement of heating/cooling channels as well as sensors to monitor tooling health and heat distribution. The pneumatically-driven pick and place actuator is integrated into the existing electrical and mechanical design and is controlled using custom M-code commands. The system is comprised mostly of commercially available components, providing easy adoptability by future thermoset systems.Mechanical Engineerin