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

The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology has lagged behind. This paper presents the major opportunities, constraints, and economic considerations for Design for Additive Manufacturing. It explores issues related to design and redesign for direct and indirect AM production. It also highlights key industrial applications, outlines future challenges, and identifies promising directions for research and the exploitation of AM's full potential in industry.

/pdf/design-for-additive-manufacturing-trends-opportunities-22heccleea.pdf

Design for additive manufacturing: trends, opportunities, considerations, and constraints

완효성 비료와 4종복비의 혼용 시용이 팔레놉시스의 생육에 미치는 효과

Design for manufacture and assembly (DFM) has typically meant that designers should tailor their designs to eliminate manufacturing difficulties and minimize manufacturing, assembly, and logistics costs. However, the capabilities of additive manufacturing technologies provide an opportunity to rethink DFM to take advantage of the unique capabilities of these technologies. As mentioned in Chap. 16, several companies are now using AM technologies for production manufacturing. For example, Siemens, Phonak, Widex, and the other hearing aid manufacturers use selective laser sintering and stereolithography machines to produce hearing aid shells; Align Technology uses stereolithography to fabricate molds for producing clear dental braces (“aligners”); and Boeing and its suppliers use polymer powder bed fusion (PBF) to produce ducts and similar parts for F-17 fighter jets. For hearing aids and dental aligners, AM machines enable manufacturing of tens to hundreds of thousands of parts, where each part is uniquely customized based upon person-specific geometric data. In the case of aircraft components, AM technology enables low-volume manufacturing, easy integration of design changes and, at least as importantly, piece part reductions to greatly simplify product assembly.

Design for Additive Manufacturing

Soft robots are capable of mimicking the complex motion of animals. Soft robotic systems are defined by their compliance, which allows for continuous and often responsive localized deformation. These features make soft robots especially interesting for integration with human tissues, for example, the implementation of biomedical devices, and for robotic performance in harsh or uncertain environments, for example, exploration in confined spaces or locomotion on uneven terrain. Advances in soft materials and additive manufacturing technologies have enabled the design of soft robots with sophisticated capabilities, such as jumping, complex 3D movements, gripping and releasing. In this Review, we examine the essential soft material properties for different elements of soft robots, highlighting the most relevant polymer systems. Advantages and limitations of different additive manufacturing processes, including 3D printing, fused deposition modelling, direct ink writing, selective laser sintering, inkjet printing and stereolithography, are discussed, and the different techniques are investigated for their application in soft robotic fabrication. Finally, we explore integrated robotic systems and give an outlook for the future of the field and remaining challenges. 3D printing can be used to directly fabricate soft robots. This Review discusses advances in 3D printing technologies and soft materials for the fabrication of soft robotic systems with sophisticated capabilities, such as 3D movement and responsiveness to the environment.

3D printing of soft robotic systems

We present a bitmap printing method and digital workflow using multi-material high resolution Additive Manufacturing (AM). Material composition is defined based on voxel resolution and used to fabricate?a design object?with locally varying material stiffness, aiming to?satisfy the design objective. In this workflow voxel resolution is set by the printer's native resolution, eliminating the need for slicing and path planning. Controlling geometry and material property variation at the resolution of the printer provides significantly greater control over structure-property-function relationships. To demonstrate the utility of the bitmap printing approach we apply it to the design of a?customized prosthetic socket. Pressure-sensing elements are concurrently fabricated with the socket, providing possibilities for evaluation of the socket's fit. The level of control demonstrated in this study?cannot be achieved using traditional CAD tools and volume-based AM workflows, implying that new CAD workflows must be developed in order to enable designers to harvest the capabilities of AM. Bitmap printing workflow enables digital fabrication in printer's native resolution.Voxel-based design and representation of objects for multi-material printing.Using 3D printed light guides, deformation of materials can be sensed.

/pdf/voxel-based-fabrication-through-material-property-mapping-13d3arndlp.pdf

Voxel-based fabrication through material property mapping

Exploring the potential of additive manufacturing for product design in a circular economy

https://repository.tudelft.nl/islandora/object/uuid%3Ad209f6d0-bd0c-4520-9b85-419d61ff916d/datastream/OBJ/download

Mechanics of bioinspired functionally graded soft-hard composites made by multi-material 3D printing

This work presents an approach to integrate actuators, sensors, and structural components into a single product that is 3D printed using Selective Laser Sintering. The behavior of actuators, sensors, and structural components is customized to desired functions within the product. Our approach is demonstrated by the realization of human-like behavior in a 3D-printed soft robotic hand. This work describes the first steps towards creating the desired behavior by means of modeling specific volumes within the product using Additive Manufacturing. Our work shows that it is not necessary to limit the design of a soft robotic product to only integrating off-the-shelf components but instead we deeply embedded the design of the required behavior in the process of designing the actuators, sensors, and structural components.

Towards Behavior Design of a 3D-Printed Soft Robotic Hand

The potential of additive manufacturing (AM) for distributed production is often mentioned as an enabler for sustainable manufacturing within a circular economy. Currently, even if manufacturing with AM is distributed, the used materials can rarely be acquired locally and are usually obtained from a centralized location. Addressing this issue, we are developing an approach that supports the search for local materials that are suitable as material input for AM and are recyclable to serve multiple product lifecycles. The approach is an iterative process consisting of four phases; “material in AM context”, “recycling opportunities”, “material property testing”, and “application possibilities”. As an initial example, we present a process to adapt mussel shell waste into AM material. Mussel shells are a voluminous waste stream in the Netherlands. The shells, which mainly exist of calcium carbonate, are ground into a powder and combined with sugar water. Using a modified material extrusion process, 3D objects are created. In this paper, we discuss the iterations through our approach and illustrate the initial 3D printed results. With this project, we intend to demonstrate the potential of using local waste streams for AM processes for a circular economy. This is a first step towards the development of a methodology for linking local material streams to novel AM processes and meaningful applications.

Eugeni L. Doubrovski

Papers

Voxel-based fabrication through material property mapping

Exploring the potential of additive manufacturing for product design in a circular economy

Mechanics of bioinspired functionally graded soft-hard composites made by multi-material 3D printing

Towards Behavior Design of a 3D-Printed Soft Robotic Hand

Local and recyclable materials for additive manufacturing: 3D printing with mussel shells