Additive manufacturing of metallic components – Process, structure and properties

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

The use of 3D printing for rapid tooling and manufacturing has promised to produce components with complex geometries according to computer designs. Due to the intrinsically limited mechanical properties and functionalities of printed pure polymer parts, there is a critical need to develop printable polymer composites with high performance. 3D printing offers many advantages in the fabrication of composites, including high precision, cost effective and customized geometry. This article gives an overview on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the fields of biomedical, electronics and aerospace engineering. Common 3D printing techniques such as fused deposition modeling, selective laser sintering, inkjet 3D printing, stereolithography, and 3D plotting are introduced. The formation methodology and the performance of particle-, fiber- and nanomaterial-reinforced polymer composites are emphasized. Finally, important limitations are identified to motivate the future research of 3D printing.

3D printing of polymer matrix composites: A review and prospective

Additive manufacturing (AM) is poised to bring about a revolution in the way products are designed, manufactured, and distributed to end users. This technology has gained significant academic as well as industry interest due to its ability to create complex geometries with customizable material properties. AM has also inspired the development of the maker movement by democratizing design and manufacturing. Due to the rapid proliferation of a wide variety of technologies associated with AM, there is a lack of a comprehensive set of design principles, manufacturing guidelines, and standardization of best practices. These challenges are compounded by the fact that advancements in multiple technologies (for example materials processing, topology optimization) generate a "positive feedback loop" effect in advancing AM. In order to advance research interest and investment in AM technologies, some fundamental questions and trends about the dependencies existing in these avenues need highlighting. The goal of our review paper is to organize this body of knowledge surrounding AM, and present current barriers, findings, and future trends significantly to the researchers. We also discuss fundamental attributes of AM processes, evolution of the AM industry, and the affordances enabled by the emergence of AM in a variety of areas such as geometry processing, material design, and education. We conclude our paper by pointing out future directions such as the "print-it-all" paradigm, that have the potential to re-imagine current research and spawn completely new avenues for exploration. The fundamental attributes and challenges/barriers of Additive Manufacturing (AM).The evolution of research on AM with a focus on engineering capabilities.The affordances enabled by AM such as geometry, material and tools design.The developments in industry, intellectual property, and education-related aspects.The important future trends of AM technologies.

The status, challenges, and future of additive manufacturing in engineering

While NASA explores the power of 3D printing in the development of the next generation space exploration vehicle, a CubeSat Trailblazer was launched in November 2013 that integrated 3D-printed structures with embedded electronics. Space provides a harsh environment necessary to demonstrate the durability of 3D-printed devices with radiation, extreme thermal cycling, and low pressure—all assaulting the structure at the atomic to macroscales. Consequently, devices that are operational in orbit can be relied upon in many terrestrial environments—including many defense and biomedical applications. The 3D-printed CubeSat module (a subsystem occupying approximately 10 % of the total volume offered by the 10 × 10 × 10-cm CubeSat enclosure) has a substrate that fits specifically into the available volume—exploiting 3D printing to provide volumetric efficiency. Based on the best fabrication technology at the time for 3D-printed electronics, stereolithography (SL), a vat photopolymerization technology, was used to fabricate the dielectric structure, while conductive inks were dispensed in channels to provide the electrical interconnect between components. In spite of the structure passing qualification—including temperature cycling, shock and vibration, and outgas testing—the photocurable materials used in SL do not provide the level of durability required for long-term functionality. Moreover, the conductive inks with low-temperature curing capabilities as required by the SL substrate material are widely known to provide suboptimal performance in terms of conductivity. To address these challenges in future 3D-printed electronics, a next generation machine is under development and being referred to as the multi3D system, which denotes the use of multiple technologies to produce 3D, multi-material, multifunctional devices. Based on an extrusion process necessary to replace photocurable polymers with thermoplastics, a material extrusion system based on fused deposition modeling (FDM) technology has been developed that integrates other technologies to compensate for FDM’s deficiencies in surface finish, minimum dimensional feature size, and porosity. Additionally, to minimize the use of conductive inks, a novel thermal embedding technology submerges copper wires into the thermoplastic dielectric structures during FDM process interruptions—providing high performance, robust interconnect, and ground planes—and serendipitously improving the mechanical properties of the structure. This paper compares and contrasts stereolithography used for 3D-printed electronics with the FDM-based system through experimental results and demonstrates an automated FDM-based process for producing features not achievable with FDM alone. In addition to the possibility of using direct write for electronic circuitry, the novel fabrication uses thermoplastics and copper wires that offer a substantial improvement in terms of performance and durability of 3D-printed electronics.

3D Printing multifunctionality: structures with electronics

In new product development, time to market (TTM) is critical for the success and profitability of next generation products. When these products include sophisticated electronics encased in 3D packaging with complex geometries and intricate detail, TTM can be compromised - resulting in lost opportunity. The use of advanced 3D printing technology enhanced with component placement and electrical interconnect deposition can provide electronic prototypes that now can be rapidly fabricated in comparable time frames as traditional 2D bread-boarded prototypes; however, these 3D prototypes include the advantage of being embedded within more appropriate shapes in order to authentically prototype products earlier in the development cycle. The fabrication freedom offered by 3D printing techniques, such as stereolithography and fused deposition modeling have recently been explored in the context of 3D electronics integration - referred to as 3D structural electronics or 3D printed electronics. Enhanced 3D printing may eventually be employed to manufacture end-use parts and thus offer unit-level customization with local manufacturing; however, until the materials and dimensional accuracies improve (an eventuality), 3D printing technologies can be employed to reduce development times by providing advanced geometrically appropriate electronic prototypes. This paper describes the development process used to design a novelty six-sided gaming die. The die includes a microprocessor and accelerometer, which together detect motion and upon halting, identify the top surface through gravity and illuminate light-emitting diodes for a striking effect. By applying 3D printing of structural electronics to expedite prototyping, the development cycle was reduced from weeks to hours.

3D Printing for the Rapid Prototyping of Structural Electronics

Fabrication of barium titanate by binder jetting additive manufacturing technology

Purpose – The purpose of this paper is to investigate the use of medical‐grade polymethylmethacrylate (PMMA) in fused deposition modeling (FDM) to fabricate porous customized freeform structures for several applications including craniofacial reconstruction and orthopaedic spacers. It also aims to examine the effects of different fabrication conditions on porosity and mechanical properties of PMMA samples.Design/methodology/approach – The building parameters and procedures to properly and consistently extrude PMMA filament in FDM for building 3D structures were determined. Two experiments were performed that examined the effects of different fabrication conditions, including tip wipe frequency, layer orientation, and air gap (AG) (or distance between filament edges) on the mechanical properties and porosity of the fabricated structures. The samples were characterized through optical micrographs, and measurements of weight and dimensions of the samples were used to calculate porosity. The yield strength, s...

Fused deposition modeling of patient‐specific polymethylmethacrylate implants

The purpose of this paper is to evaluate the capability of five desktop additive manufacturing (AM) machines based on the ability to produce a standard component This work also developed a model/method for evaluating and ranking AM technologies based on select criteria that can facilitate purchasing decisions A standard part was designed and printed on each machine, and evaluated based on dimensional accuracy and surface finish Additionally, the machines were compared based on build time for single and multiple parts as well as material consumption and unit cost The research highlights the differences between AM units and suggests a method by which to ascertain the differences With the rapid proliferation of desktop additive manufacturing units, a quantitative ranking system was developed to rate the units so a comparison can be made Although the focus of the work was on desktop systems, the approach can be applied across all AM technologies

David Espalin

Papers

3D Printing multifunctionality: structures with electronics

3D Printing for the Rapid Prototyping of Structural Electronics

Fabrication of barium titanate by binder jetting additive manufacturing technology

Fused deposition modeling of patient‐specific polymethylmethacrylate implants

3D printer selection: A decision-making evaluation and ranking model