Additive Manufacturing Capabilities Research Articles

Characterisation of powder and microstructure, density and surface roughness for additively manufactured stent using medical grade ASTM F75 cobalt chromium (CoCrMo) by selective laser melting (SLM) technology

ABSTRACT This paper explains and demonstrates the capabilities of Metal Additive Manufacturing (MAM) technology in producing intricate stent structure with a customise design by using ASTM F75 Cobalt-Chromium (CoCrMo) powder. Current commercialise stent in the market is rigid in size and geometries and the cost of tooling and manufacturability are increased once the other stent production is replaced. The design, process parameter, powder characterisation, part density and microstructure were investigated and thus exploring the potential area of MAM process for future proof stent manufacturing. Average density achieved for the seven (7) additive-manufactured stents was within 92– 97%, whereas the shrinkage is in between 0.31% and 0.61% (diameter) and 0.03–0.05% (height) respectively. The average surface roughness achieved are 4.1 µm (highest peak) whereas the lowest peak was 365.1 nm. The suggested model of the stent was taken from the third-party vendor and fabrication was carried out using EOSINT M280 metal printer with the aid of Materialise Magics 19.0 software for support generation.

Sensitivity of Micromilling Responses to Grain Variations in Wire Arc Additively Manufactured Aluminum Alloy 4043

Abstract Given the recent trend toward hybrid processing involving the integration of wire arc additive manufacturing (WAAM) and machining capabilities, this paper aims to identify and correlate microstructural variations observed in wire arc additively manufactured aluminum alloy 4043 workpieces to their specific micromilling responses. This is done with the explicit goal of assessing the feasibility of using micromilling responses to detect microstructural variations in WAAM workpieces. As part of this effort, variations in the interlayer cooling time are used to induce changes in the microstructure of a thin-wall WAAM workpiece. The microstructures are first characterized using in-process thermographic imaging, optical microscopy, polarized light microscopy, and indentation. Micromilling slotting experiments are then conducted on different regions within the workpiece. The findings suggest that cutting force signals are the premier candidate for in situ extraction of information regarding microstructural variations within WAAM workpieces. In particular, in situ analysis of the cutting force frequency spectrum can provide critical information regarding dominant failure mechanisms related to the underlying microstructure. Other key micromilling responses such as surface roughness, burr formation, and tool wear also correlate well with the underlying microstructural variations. While these early stage findings hold promise, future research efforts spanning multiple metal alloys systems and micromachining processes are needed to mature the proposed concept.

New Feedstock System for Fused Filament Fabrication of Sintered Alumina Parts.

Only a few 3D-printing techniques are able to process ceramic materials and exploit successfully the capabilities of additive manufacturing of sintered ceramic parts. In this work, a new two component binder system, consisting of polyethyleneglycol and polyvinylbutyral, as well stearic acid as surfactant, was filled with submicron sized alumina up to 55 vol.% and used in fused filament fabrication (FFF) for the first time. The whole process chain, as established in powder injection molding of ceramic parts, starting with material selection, compounding, measurement of shear rate and temperature dependent flow behavior, filament fabrication, as well as FFF printing. A combination of solvent pre-debinding with thermal debinding and sintering at a reduced maximum temperature due to the submicron sized alumina and the related enhanced sinter activity, enabled the realization of alumina parts with complex shape and sinter densities around 98 % Th. Finally the overall shrinkage of the printed parts were compared with similar ones obtained by micro ceramic injection molding.

Metal Additive Manufacturing: Considering the Relationship Between Alloy and Application

Abstract Case studies from a range of industries illustrate how advanced additive manufacturing capabilities optimize both material performance and value. The materials discussed are Inconel 718, Ti-6Al-4V, aluminum F357, and Hastelloy X.

Additive creativity: investigating the use of design for additive manufacturing to encourage creativity in the engineering design industry

ABSTRACT The capabilities of additive manufacturing (AM) enable designers to generate and build creative solutions beyond the limitations of traditional manufacturing. However, designers must also accommodate AM limitations to minimize build failures. Several researchers have proposed design tools and educational interventions for integrating design for AM (DfAM) in engineering design. However, there is a need to investigate the effect of DfAM training on industry professionals’ use of these techniques and its subsequent effects on the creativity of their designs. In this paper, we present a workshop-based study in which industry professionals were sequentially introduced to opportunistic and restrictive DfAM. Participants were also given a DfAM task, with short idea generation sessions conducted between each content lecture. The participants’ designs and their DfAM and creative self-efficacies were compared from before to after receiving DfAM training. The results show that DfAM training successfully increased participants’ restrictive DfAM self-efficacy; however, no changes were seen in their opportunistic DfAM or creative self-efficacies. Further, the results show an increase in the uniqueness and overall creativity of the participants’ designs, but no significant changes were seen in the initially high usefulness of the designs. These findings suggest that DfAM training presents an opportunity to encourage creative idea generation.

A legend reborn: Additive manufacturing creates Wootz-Damascus steel

Artisans in ancient India melted iron with woodchips as sources of carbon in clay crucibles and produced a hypereutectoid steel (C content ∼1.5% by weight) called Wootz steel. Their technique, perfected over centuries, resulted in steels of high strength and ductility. These steels were traded in Damascus and spread to many countries, which turned them into swords of amazing performance with aesthetically pleasing wavy patterns on the surface. Combining the expertise of researchers at the Max Planck Institute for Iron Research in alloy design with that in laser processing by a team at the Fraunhofer Institute for Laser Technology, a new Damascus-like steel has now been created by additive manufacturing (AM), commonly known as three-dimensional (3D) printing. The key to the success of this work, as reported in a recent issue of Nature (doi:10.1038/s41586-020-2409-3), is the innovative use of the digital capabilities of AM to introduce a controlled hierarchical structure without the need for post-treatment.

Transformational Challenge Reactor preconceptual core design studies

In the nuclear industry, a manufacturing-informed design approach has the potential to yield the most benefit from advanced manufacturing. By leveraging advanced materials, data science, and rapid testing and deployment, manufacturing-informed design can drive down costs and development times, ultimately improving future commercial viability. This approach is being demonstrated in the US Department of Energy Office of Nuclear Energy (DOE-NE) Transformational Challenge Reactor (TCR) program. Preconceptual design activities for TCR have been focused on analyzing and maturing four reactor core design concepts: two fast-spectrum and two thermal-spectrum systems. The designs were iteratively modified and analyzed, and subcomponents were manufactured in parallel over weeks instead of months or years. To meet key program initiatives (e.g., timeline and material use), several constraints—including fissile material availability, component availability, materials compatibility, and additive manufacturing capabilities—were factored into the design effort, yielding small cores less than one cubic meter in volume with near-term viability.The TCR program has made significant progress on development of advanced moderator materials such as yttrium hydride, advancing the feasibility of gas-cooled thermal spectrum systems using less than 250 kg of high-assay low enriched uranium (HALEU) and occupying less than 1 m3. Each of the two resulting thermal designs uses a different fuel form: traditional UO2 ceramic fuel and tristructural isotropic (advanced TRISO) fuel particles embedded inside a SiC matrix. Core neutronics and thermal performance for these systems were assessed and summarized. Evaluation of the performance metrics for these two moderated designs has yielded the downselected TCR design: a TRISO-fueled and yttrium hydride moderated gas-cooled reactor.

3D printed deformable sensors.

The ability to directly print compliant biomedical devices on live human organs could benefit patient monitoring and wound treatment, which requires the 3D printer to adapt to the various deformations of the biological surface. We developed an in situ 3D printing system that estimates the motion and deformation of the target surface to adapt the toolpath in real time. With this printing system, a hydrogel-based sensor was printed on a porcine lung under respiration-induced deformation. The sensor was compliant to the tissue surface and provided continuous spatial mapping of deformation via electrical impedance tomography. This adaptive 3D printing approach may enhance robot-assisted medical treatments with additive manufacturing capabilities, enabling autonomous and direct printing of wearable electronics and biological materials on and inside the human body.

Characterisation of elemental analysis, carbon sulphur analysis and impact test of stent manufacturing using medical grade ASTM F75 cobalt chromium (CoCrMo) by selective laser melting (SLM) technology

ABSTRACT This paper explains and demonstrates the capabilities of metal additive manufacturing (MAM) technology in producing intricate stent structure with a customise design by using ASTM F75 cobalt chromium powder. The elemental analysis (EDX-SEM), carbon sulphur analysis and Impact Test are being develop and tested and thus exploring the potential area of MAM process for future proof stent manufacturing. By alternatively switching to MAM, the step of production can be minimised and thus customisation of stent can be carried out according to the patient’s need. The suggested model of the stent was taken from the third-party vendor and fabrication was carried out using EOSINT M280 metal printer with the aid of Materialise Magics 19.0 software for support generation.

In Situ Nanocomposite Fabrication for RF Electronics Applications With Additive Manufacturing

Using additive manufacturing (AM), in this article, we show the dynamic mixing of polymer ceramic composite materials during the 3-D printing process. Using this in situ mixing strategy, we print polyimide and barium titanate (BaTiO 3) nanocomposite films with variable levels of ceramic loading. This is accomplished with multimaterial aerosol jet printing. The relative dielectric constant and loss tangent of these composite materials are characterized using two ring resonator circuits designed for the first resonance below 12 and 110 GHz, respectively. This yields material characterization results from the X-band to the W-band. We use these results to estimate the ceramic loading by volume in the composites. In addition, we use scanning electron microscopy and energy-dispersive X-ray spectroscopy to characterize the dispersion and ceramic loading of the composite films. Using this process, we demonstrate a range of relative dielectric constants from 3.1 to 8.9. To demonstrate the capabilities of this process, a continuous gradient of material is also shown in a printed film. Finally, we demonstrate a slightly modified process in order to lower the loss characteristics of the printed films to provide insight into the loss mechanisms. By mixing composites in situ, we are able to dynamically alter the ceramic loading of the printed material without formulating multiple inks and pattern 3-D structures without the use of photosensitive materials. This allows us to manufacture material gradients and patterns that would otherwise be impractical to fabricate using conventional microfabrication. Using composite mixing in place adds a new dimension to the flexibility and capability of AM.

SUPPORTING ADDITIVE MANUFACTURING TECHNOLOGY DEVELOPMENT THROUGH CONSTRAINT MODELLING IN EARLY CONCEPTUAL DESIGN: A SATELLITE PROPULSION CASE STUDY

AbstractFunction and constraints modelling are implemented to design two gridded ion thrusters for additive manufacturing (AM). One concept takes advantage of AM design freedom, disregarding AM limitations and is not feasible. The other concept considers AM limitations and is manufacturable and feasible. Constraints modelling highlights AM capabilities that can be improved, showing where future investment is needed. Constraints representation can also support the creation of technology development roadmaps able to identify areas of AM technologies that must be improved.

Design, fabrication and validation of an improved coil for induction dilatometry

Dilatometry is a versatile tool to investigate thermal expansion or phase transformations in various materials based on the length changes upon heating and cooling. Since most modern thermal processes tend to take place at high heating and cooling rates it can be demonstrated that a large longitudinal temperature gradient within dilatometric samples impedes the accurate investigation of physical mechanisms. In this study we investigate how an instrumental advancement of the induction heating system can be implemented in a dilatometric setup in order to mitigate the temperature gradient and its effect on the measured length change for a wide range of heating rates. For this purpose a numerical method for heating design optimization using a FEM simulation of the dilatometric experiment is developed and validated. The presented heating component design method in combination with additive manufacturing capabilities allows for a more accurate and flexible method of detecting dilatation in a dilatometric setup. Extreme temperature differences of 140∘C for a maximum heating rate of 800∘C/s could be reduced by 15-45% within the sample using new optimized instrumentation. This leads to a more profound and exact interpretation of dilatometric data for high heating rates and complex time temperature profiles.

Mechanical Properties of 3D Nanostructures Obtained by Focused Electron/Ion Beam-Induced Deposition: A Review.

This article reviews the state-of-the -art of mechanical material properties and measurement methods of nanostructures obtained by two nanoscale additive manufacturing methods: gas-assisted focused electron and focused ion beam-induced deposition using volatile organic and organometallic precursors. Gas-assisted focused electron and ion beam-induced deposition-based additive manufacturing technologies enable the direct-write fabrication of complex 3D nanostructures with feature dimensions below 50 nm, pore-free and nanometer-smooth high-fidelity surfaces, and an increasing flexibility in choice of materials via novel precursors. We discuss the principles, possibilities, and literature proven examples related to the mechanical properties of such 3D nanoobjects. Most materials fabricated via these approaches reveal a metal matrix composition with metallic nanograins embedded in a carbonaceous matrix. By that, specific material functionalities, such as magnetic, electrical, or optical can be largely independently tuned with respect to mechanical properties governed mostly by the matrix. The carbonaceous matrix can be precisely tuned via electron and/or ion beam irradiation with respect to the carbon network, carbon hybridization, and volatile element content and thus take mechanical properties ranging from polymeric-like over amorphous-like toward diamond-like behavior. Such metal matrix nanostructures open up entirely new applications, which exploit their full potential in combination with the unique 3D additive manufacturing capabilities at the nanoscale.

Study on machinability of additively manufactured and conventional titanium alloys in micro-milling process

Capability of Additive Manufacturing (AM) technology in the production of complex parts with high flexibility has led to the growing interest in their application as an alternative for conventional manufacturing processes. Despite the outstanding benefits of the AM process, due to their poor surface quality, the precision parts produced by this method generally need to be machined, ground, or polished. This paper addresses the machinability of AM Ti6Al4V titanium alloy parts in the micro-milling process with a specific focus on cutting forces, specific cutting energy, burr formation, and surface quality. Additive parts were produced by Electron Beam Melting (EBM) technique and were compared with the extruded Ti6Al4V parts in the micro-milling process. No significant difference could be observed in the cutting forces of both materials at chip thicknesses between 7.4 and 37.3 μm, despite the higher hardness of the EBM Ti6Al4V compared to the extruded Ti6Al4V. However, micro-milling of the EBM parts produced finer surfaces. Cutting forces and specific cutting energies of EBM parts were less than those of extruded parts at minimal chip thicknesses (lower than 7.4 μm). Continuous wavy-type burrs were formed in micro-milling of the EBM Ti6Al4V and were larger than those of extruded Ti6Al4V.

Incorporating Steric Hindrance into the Additive Design Enables a Robust Formulation of Alumina Ink for Extrusion-based 3D Printing

The capabilities of additive manufacturing for fabrication of complex and thin-walled ceramic-based objects are restricted by the availability of ceramics inks. Formulations of current ink systems ...

A Design Framework for Additive Manufacturing: Integration of Additive Manufacturing Capabilities in the Early Design Process

Additive manufacturing has emerged as an integral part of modern manufacturing because of its unique capabilities in various application domains. As efforts to effectively apply additive manufacturing, design for additive manufacturing (DfAM) has risen to provide a set of guidelines based on a practical design framework or a methodology during the product design process of additive manufacturing. However, most existing DfAM methods do not effectively consider the capabilities of extant additive manufacturing technologies in the early design stages, and therefore it is hard to map functional requirements from customer needs onto a product design for additive manufacturing. Moreover, available DfAM methods tend to rely on the direct application of a specific decision method rather than a systematic approach with appropriate deployment and transformation of available design decision methods considering the additive manufacturing environment. Consequently, existing DfAM methods lack suitability for use by additive manufacturing novices. To tackle these issues, this study develops a design framework for additive manufacturing through the integration of axiomatic design and theory of inventive problem-solving (TRIZ). This integrated approach is effective because the axiomatic design approach can be used to systematically define and analyze a design problem, while the TRIZ problem-solving approach combined with an additive manufacturing database can be used as an idea generation tool to generate innovative solutions for the design problem. A case study for a housing cover redesign is presented to apply and validate the proposed design framework.

Obfuscation of Embedded Codes in Additive Manufactured Components for Product Authentication.

Enhancement in the capabilities of additive manufacturing (AM) methods has led to development of many high-value components for aerospace, automotive and medical fields. Security concerns, such as (a) a predominantly cloud based process chain of AM may be breached and stolen files can be used for unauthorized reproduction of parts and (b) legitimately acquired parts can be reverse engineered, need to be addressed for this field to protect intellectual property and deter counterfeiting or unauthorized production. In the present work, a method of embedding an identification code inside the parts manufactured by AM methods is presented, which takes advantage of the layer-by-layer manufacturing process. The code is obfuscated by segmenting it into a specific number of parts, which are distributed throughout a large number of printed layers. In this case, viewing the code only from a specific direction is provides the correct visualization. A further obfuscation scheme is demonstrated that embeds multiple identification codes in the interpenetrating format. Only a specific set of processing conditions can lead to printing of the authentic code inside the part correctly. Numerous other conditions lead to printing of wrong code inside the part, which will lead to positive identification of counterfeit or unauthorized parts. Securing the AM process chain can help in accelerating the industrial applications of this versatile method.

Exploratory study on the perception of additively manufactured end-use products with specific questionnaires and eye-tracking

The outreach of application domains for Additive Manufacturing (AM) is expanding and end-use products represent their next frontier. Contextually, design methods are developed for exploiting the unique AM capabilities. They largely benefit from the knowledge about peculiarities, constraints and technical performances of the various AM processes and devices. However, while the mechanical properties of objects created with AM are widely studied, there is lack of research on emotional and perceptual aspects. This is of great relevance in the mentioned perspective of employing AM for end-use products. The paper aims to elucidate which perceptual mechanisms are activated when a user observes an object generated with AM instead of traditional technologies. An experiment has involved 43 participants who have evaluated ten pairs of objects, constituted by a commercial product and a replica made with Fused Deposition Modelling. Testers have answered a questionnaire, as well as their visual behavior has been recorded with eye-tracking glasses. Based on results, replicas suffer from poor attractiveness and especially low perceived quality. They have also given rise to more careful exploratory behaviors because they likely require a lengthier examination for testers’ assessment or they arouse curiosity. It can be inferred that Fused Deposition Modelling does not exhibit sufficient accuracy to achieve acceptability with reference to everyday products. Nevertheless, it is also deemed that limited improvements might compensate for the perception of technical unsuitability this technology engenders. This can be verified by repeating the experiment with more sophisticated and precise AM devices.

Selective Laser Melting of a 1U CubeSat structure. Design for Additive Manufacturing and assembly

The aerospace industry has used Additive Manufacturing (AM) since its beginnings in the ‘80s because of its unique capabilities. The present work shows a re-designing and the manufacturing via AM of the structural sub-system of a CubeSat from the nanosatellite class. Specifically, a 1U CubeSat design proposal has been developed according to Design for Additive Manufacturing (DFAM) guidelines, considering the consolidation of the parts for reducing and/or avoiding the assembly issues. A configuration made of only two parts has been successfully fabricated via Selective Laser Melting (SLM) technology. AM capabilities allowed to integrate a hinge mechanism in the design, making the resulting structure an already-assembled one. Moreover, the design exhibits snap-fit features in order to get rid of fasteners. The increased complexity of the parts due to the integration of the additional snap-fit features results in no manufacturing issues due to the AM capability to manage shape complexity. This work points AM out as a key technology allowing for a drastic reduction of the part count for a mechanical system, taking Design for Assembly (DFA) guidelines to the extreme. It underlines the need to consider AM-related constrains already in the design phase, such as the clearance and the shape of the hinge and the snap joint matching SLM specific constraints such as support structures design and removal planning, part orientation in the building platform, and hollowing out for powder removal.

Why manufacturers adopt additive manufacturing technologies: The role of sustainability

Emerging manufacturing technologies can affect the performance of manufacturing systems considerably. Hence, a proportionate and purposive choice of such technologies would significantly impact the success of a firm. Additive Manufacturing, a leading and impactful technology, is being implemented in many industrial sectors and for a variety of reasons. It presents huge potential benefits in terms of sustainability perspectives. This paper aims to identify and prioritize the determinants of its adoption as well as to clarify the role of sustainability benefits in the decision to adopt. Then, the research seeks to distinguish the priorities of different application sectors through a multi-stage survey. The results show that environmental sustainability benefits are barely relevant to adoption decisions in practice and this is in contrast with the literature stating the huge sustainability benefits. Moreover, the results prove the pivotal role of economic motives in adoption decisions. The findings also indicate that the capability of additive manufacturing for producing almost any complex design is the key driver of its adoption in all sectors.