Unified Software for Multi-Functional G-Code: A Method for Implementing Multi-Technology Additive Manufacturing

Additive manufacturing (AM) began a manufacturing revolution moving industrial production into consumer homes. With interest shifting toward multi-functional parts fabricated through AM technologies, multi-functional fabrication systems are now being developed. Merging different manufacturing technologies into a single machine is a challenge, but ongoing research in the development of multi-technology systems has shown promise. The software and automation aspects of multi-technology systems are being developed in unison. This paper explores the challenges and approaches to developing software that interfaces with multifunctional CADs and creates files for direct use in multi-technology AM machines.Mechanical Engineerin

Cooperative Fabrication Methodology for Embedding Wireon Corved Surfaces

In conventional additive manufacturing (AM), an object is fabricated by depositing material in a layer by layer fashion. Typically, this process is retained so that deposition can occur on flat surfaces and motion can be constrained to requiring only three degrees of freedom (DOF) in a Cartesian coordinate system. When incorporating wire in three-dimensional (3D) objects, there is sometimes a need for placement along curved surfaces on which positions are defined not only by 3D Cartesian coordinates but also angular ones. Therefore, a minimum of two additional DOFs are required allowing movement to be generated at the build platform as well as of the extrusion head. This paper addresses a method for trajectory planning of both systems, that is, the extrusion head and the movable build platform, allowing for cooperative and harmonic motion between the two.Mechanical Engineerin

TESTING PROTOCOL DEVELOPMENT FOR FRACTURE TOUGHNESS OF PARTS BUILT WITH BIG AREA ADDITIVE MANUFACTURING

Mechanical testing of additively manufactured parts has largely relied on existing standards developed for traditional manufacturing. While this approach leverages the investment made on current standards development, it inaccurately assumes that mechanical response of AM parts is identical to that of parts manufactured through traditional processes. When considering thermoplastic, material extrusion AM, differences in response can be attributed to an AM part’s inherent inhomogeneity caused by porosity, interlayer zones, and surface texture. Additionally, interlayer bonding of parts printed with large-scale AM is difficult to adequately assess as much testing is done such that stress is distributed across many layer interfaces; therefore, the lack of AM-specific standard to assess interlayer bonding is a significant research gap. To quantify interlayer bonding via fracture toughness, double cantilever beam (DCB) testing has been used for some AM materials, and DCB has been generally used for a variety of materials including metal, wood, and laminates. Mode I DCB testing was performed on thermoplastic matrix composites printed with Big Area Additive Manufacturing (BAAM). Of particular interest was the crack shape and deflection speed during testing. A modernization of the testing process was proposed using visual processing of a recording of the crack propagation to get more accurate calculations. Results discuss the differences when using two crack types and three deflection speeds.Mechanical Engineerin

3D Printing Multi-Functionality: Embedded RF Antennas and Components

Significant research and press has recently focused on the fabrication freedom of Additive Manufacturing (AM) to create both conceptual models and final end-use products. This flexibility allows design modifications to be immediately reflected in 3D printed structures, creating new paradigms within the manufacturing process. 3D printed products will inevitably be fabricated locally, with unit-level customization, optimized to unique mission requirements. However, for the technology to be universally adopted, the processes must be enhanced to incorporate additional technologies; such as electronics, actuation, and electromagnetics. Recently, a novel 3D printing platform, Multi3D manufacturing, was funded by the presidential initiative for revitalizing manufacturing in the USA using 3D printing (America Makes - also known as the National Additive Manufacturing Innovation Institute). The Multi3D system specifically targets 3D printed electronics in arbitrary form; and building upon the potential of this system, this paper describes RF antennas and components fabricated through the integration of material extrusion 3D printing with embedded wire, mesh, and RF elements

INVESTIGATION OF INSTRUMENTING ROBOCASTING PRINTER FOR CERAMIC SLURRIES

Robocasting has multiple steps from ceramic slurry preparation to sintering that can impact the end part quality. In-situ monitoring and process controls can aid in minimizing differences in the quality of printed parts. The study and impact of different parameters during the printing process and a parameter database will improve the quality between green bodies and sintered parts. This paper discusses implementation of a CMOS camera, dynamic pressure sensor, and 2D laser scanner into a custom-built robocasting printer for in process monitoring. Single line beads were printed and analyzed by measuring the dimensions and pressure changes during printing. Results show that the printer with sensors detected the location of possible defects and changes in printed samples but further investigation is needed to filter noise and collect conclusive data.Mechanical Engineerin

Optimisation of substrate angles for multi-material and multi-functional inkjet printing

Three dimensional inkjet printing of multiple materials for electronics applications are challenging due to the limited material availability, inconsistencies in layer thickness between dissimilar materials and the need to expose the printed tracks of metal nanoparticles to temperature above 100 °C for sintering. It is envisaged that instead of printing a dielectric and a conductive material on the same plane, by printing conductive tracks on an angled dielectric surface, the required number of silver layers and consequently, the exposure of the polymer to high temperature and the build time of the component can be significantly reduced. Conductive tracks printed with a fixed print height (FH) showed significantly better resolution for all angles than the fixed slope (FS) sample where the print height varied to maintain the slope length. The electrical resistance of the tracks remained under 10Ω up to 60° for FH; whereas for the FS samples, the resistance remained under 10Ω for samples up to 45°. Thus by fixing the print height to 4 mm, precise tracks with low resistance can be printed at substrate angles up to 60°. By adopting this approach, the build height “Z” can be quickly attained with less exposure of the polymer to high temperature

Automatic Layerwise Acquisition of Thermal and Geometric Data of the Electron Beam Melting Process using Infrared Thermography

Layerwise monitoring has become an area of interest in the field of additive manufacturing because of potential to further enable part qualification during every stage of fabrication. Spatial monitoring and qualification during part fabrication has never before been possible with traditional manufacturing processes such as milling or casting. An IR camera has been externally annexed atop an EBM system to obtain layerwise thermographs throughout the fabrication process. This paper demonstrates a process to compare each layer of fabrication using automatically acquired thermal images to the corresponding CAD file for each fabricated object. Two different methods of image analysis for part detection were compared (analysis on the basis of color and analysis by edge detection). Detection allowed the quantification of processing information (average temperature and surface anomalies) and geometric information (surface area and perimeter). A percent error of the compared surface area was found to range from 5%- 17%, and automatically acquired temperature measurements were within 7.8K of the recorded thermograph. The methods presented in this research showcase the beginning steps of integrated metrology in advanced manufacturing systems and automatic monitoring of per-part thermal behavior and part quality.Mechanical Engineerin

Folding Endurance Appraisal for Thermoplastic Materials Printed in Fusion Deposition Technology

The anisotropic behavior of the fusion deposition modeling (FDM) machines could change the mechanical properties of the materials in the layer by layer technology. In general, the tensile, compressive and flexural strength are decreased against molded plastics. Some lasting products need the iteration of low flexural strength and high elongation to obtain an effective flexibility to bend in repetitive movements. The present work provides an analysis of the capacity of several selected thermoplastics materials such as Nylon (PA), Polyethylene Terephthalate (PETG), Polylactide (PLA), Polyurethane (TPU) and Polypropylene (PP) in order to test the maximal load capacity and the number of folding cycles sustained in perpendicular direction of movement. Results demonstrate that those of similar to injected molded products, PP and TPU materials surpass one million of cycles in the folding test. Yet, in axial load they have lower strength against the other considered materials.Mechanical Engineerin

EBM Fabrication and Characterization of High Purity Niobium for Superconductor Applications

Superconducting radio frequency (SRF) cavities are used to accelerate charged particles to near the speed of light for elemental studies. Currently, SRF cavities are typically fabricated using different forming processes including deep-drawing and spinning to mechanically shape niobium into the desired geometry. This research presents the development of processing parameters for high purity niobium (powder size range of 25-125μm) using electron beam melting additive manufacturing technology. Fabrication parameters were improved to obtain dense parts in a time-efficient manner. A specific procedure was used to maintain powder purity, and powder chemistry was monitored at different stages of fabrication. In addition, a series of experiments were performed to obtain 99.9% dense parts and a maximum building height of ~85mm.Mechanical Engineerin

Binder Jetting of High Temperature and Thermally Conductive (Aluminum Nitride) Ceramic

This work reports on the novel fabrication of aluminum nitride (AlN) complex components using binder jetting, on the use of sintering and hot isostatic pressing (HIPing) to increase their density, and on the characterization of the printed material, including thermal conductivity. The HIPing parameters employed were a temperature of 1900 °C using a rich nitrogen atmosphere at a pressure of 30,000 psi during 8 h. Results show that the printed and HIPed AlN components had a 1.96 g/cm3 (60.12%) density when compared to theoretical values. The thermal conductivity for densified and HIPed components was measured in the range from 23 °C to 500 °C resulting in values from 4.82 W/m*K to 3.17 W/m*K, respectively. Characterization using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction was used to investigate the ceramic structural morphology of the sintered and HIPed material, its chemical composition, and crystal structure of the binder jetting manufactured AlN components.Mechanical Engineerin