From 3D Models to 3D Prints: an Overview of the Processing Pipeline

Due to the wide diffusion of 3D printing technologies, geometric algorithms for Additive Manufacturing are being invented at an impressive speed. Each single step, in particular along the Process Planning pipeline, can now count on dozens of methods that prepare the 3D model for fabrication, while analysing and optimizing geometry and machine instructions for various objectives. This report provides a classification of this huge state of the art, and elicits the relation between each single algorithm and a list of desirable objectives during Process Planning. The objectives themselves are listed and discussed, along with possible needs for tradeoffs. Additive Manufacturing technologies are broadly categorized to explicitly relate classes of devices and supported features. Finally, this report offers an analysis of the state of the art while discussing open and challenging problems from both an academic and an industrial perspective.Comment: European Union (EU); Horizon 2020; H2020-FoF-2015; RIA - Research and Innovation action; Grant agreement N. 68044

Process Planning for Additive Manufacturing of Geometries with Variable Overhang Angles using a Robotic Laser Directed Energy Deposition system

In the present work, a novel Laser Directed Energy Deposition (LDED) process planning methodology is proposed to build a dome structure with variable overhang angles. Overhang structures with different overhang angles were built where the maximum angle of 35° can be used to build overhang structures without the process and structure compromise. The thin-wall hemispherical dome built using the developed methodology shows the maximum deviation of 2% with respect to the diameter of the original CAD model data. The study paves a way for building high-value, lightweight thin-walled structures with complex cylindrical-based shape (e.g., storage tanks, nozzles, combustion chambers) for engineering applications.Federal development of Ontario (Fed-Dev) || Promation Engineering

High Temperature Epoxy Composites for Material Extrusion Additive Manufacturing

The geometric design freedom, short lead time, and customization make additive manufacturing (AM) increasingly popular. In addition to rapid prototyping and three-dimensional molds, additive manufacturing has created wind turbine blades, robotic arms, and custom medical implants. Major manufacturing companies such as Porsche and Aetrex are utilizing AM to customize automotive seats and orthopedic footwear. However, available materials limit AM applications. Currently, the high-temperature requirements from the aerospace and automotive industries provide additional, unmet challenges. Many high-temperature epoxies have high pre-polymer viscosities and produce highly exothermic cure reactions, which limits volumetric scaling. Traditionally, fast, high-temperature processing reduces the viscosity, filling a mold before crosslinking initiation; however, this is not possible for AM. Currently, epoxy-fiber composites replace many traditional materials, such as aluminum, in applications where their high strength-to-weight ratios reduce lifetime energy costs. Fiber composites are limited by current fabrication methods, which can be expensive with limited geometric adaptability. Direct ink write (DIW) AM extrudes viscoelastic feedstock, creating parts layer-by-layer. The ink feedstock can readily incorporate fibers while AM produces parts without a mold reducing start-up requirements. This work develops a high temperature, heated cure epoxy feedstock for DIW applications achieving strength and modulus values of 145 MPa and 4.9 GPa, respectively. Two pre-polymers are combined, to maintain a glass transition temperature upwards of 285°C while reducing the viscosity. A heated deposition system requires understanding the thermal viscosity and cure profiles. With a viscosity of 5.4 Pa.s and an 18-hour pot life, 70°C allows for shear flow without premature cure during extrusion. An upper loading limit of 30 vol% glass fibers was determined. The fibers improve the heat deflection temperature by 100°C to 320°C and yield a 160% increase in flexure modulus; however, a 34% reduction in strength occurs. While processing did not decrease the fiber length as observed with carbon, the initial distribution contained 15% of fibers shorter than the critical length. The short fibers and pores that arose from both processing and dissimilar fiber-matrix expansion can account for the reduction. This work aims to develop a hightemperature fiber-filled feedstock while broadly considering print and extrusion parameters of viscous inks

Model-based design of AM components to enable decentralized digital manufacturing systems

Additive manufacturing (AM) is a versatile technology that could add flexibility in manufacturing processes, whether implemented alone or along other technologies. This technology enables on-demand production and decentralized production networks, as production facilities can be located around the world to manufacture products closer to the final consumer (decentralized manufacturing). However, the wide adoption of additive manufacturing technologies is hindered by the lack of experience on its implementation, the lack of repeatability among different manufacturers and a lack of integrated production systems. The later, hinders the traceability and quality assurance of printed components and limits the understanding and data generation of the AM processes and parameters. In this article, a design strategy is proposed to integrate the different phases of the development process into a model-based design platform for decentralized manufacturing. This platform is aimed at facilitating data traceability and product repeatability among different AM machines. The strategy is illustrated with a case study where a car steering knuckle is manufactured in three different facilities in Sweden and Italy

Additive Manufacturing Technologies and Applications

The present Special Issue proposes articles in the area of Additive Manufacturing with particular attention to the different employed technologies and the several possible applications. The main investigated technologies are the Selective Laser Sintering (SLS) and the Fused Deposition Modelling (FDM). These methodologies, combined with the Computer Aided Design (CAD), provide important advantages. Numerical, analytical and experimental knowledge and models are proposed to exploit the potential advantages given by 3D printing for the production of modern systems and structures in aerospace, mechanical, civil and biomedical engineering fields. The 11 selected papers propose different additive manufacturing methodologies and related applications and studies

Rephrasing construction: the emergence of 3D printed clay building

With an increasing concern for the future of the built environment, sustainability and efficiency have become popular terms in many industries, including architecture. Through the development of computational technologies and 3D printers, many studies show the potential to revolutionize traditional design and construction methods. This essay explores the potential of clay 3D printing and materials, focusing on the uniqueness of clay as a construction material, including its sustainability and versatility. The essay delves into the difference between printing a large-scale continuous print versus printing individual elements, highlighting the benefits and drawbacks of each approach. Two case studies, Digital Adobe and TECLA, are analyzed in depth, showcasing the real-world application of continuous and discrete clay 3D printing processes. Subsequently, the discussion is shifted onto such a technology’s future viability and potential. With the ultimate goal of providing insights into how this technology can be integrated into the traditional construction process to achieve better outcomes for the environment and the building industry as a whole

Methods to Reduce Energy and Polymer Consumption for Fused Filament Fabrication 3D Printing

Fused Filament Fabrication (FFF) 3D printing is an additive technology used to manufacture parts. Used in the engineering industry for prototyping polymetric parts, this disruptive technology has been adopted commercially and there are affordable printers on the market that allow for at-home printing. This paper examines six methods of reducing the energy and material consumption of 3D printing. Using different commercial printers, each approach was investigated experimentally, and the potential savings were quantified. The modification most effective at reducing energy consumption was the hot-end insulation, with savings of 33.8–30.63%, followed by the sealed enclosure, yielding an average power reduction of 18%. For material, the most influential change was noted using ‘lightning infill’, reducing material consumption by 51%. The methodology includes a combined energy- and material-saving approach in the production of a referenceable ‘Utah Teapot’ sample object. Using combined techniques on the Utah Teapot print, the material consumption was reduced by values between 55.8% and 56.4%, and power consumption was reduced by 29% to 38%. The implementation of a data-logging system allowed us to identify significant thermal management and material usage opportunities to minimise power consumption, providing solutions for a more positive impact on the sustainable manufacturing of 3D printed parts

Wire-arc additive manufacturing of structures with overhang: Experimental results depositing material onto fixed substrate

As additive manufacturing (AM) technology grows both more advanced and more available, the challenges and limitations are also made more evident. Most existing solutions for AM build structures layer by layer using strictly vertical material deposition. As each layer must vertically adhere to the previous layer, support structures must be added if there are to be any kinds of overhangs. For methods requiring the build to be performed within a chamber, the size of the structure is also very limited. The research presented in this paper explores possible solutions to these challenges, focusing on wire-arc additive manufacturing in order to effectively build structures that can not easily be constructed using in-box, layer-based methods for AM. By non-vertical material deposition using an industrial robot manipulator, metal structures with overhangs are built onto a fixed, horizontal surface without any support structures. Cross sections of two different structures are examined by optical microscopy and hardness measurements to reveal potential differences between the areas with and without intersections or overhang.publishedVersio