Alternative Manufacturing Technologies Research Articles

Simultaneous fabrication of multiple tablets within seconds using tomographic volumetric 3D printing

3D printing is driving a shift in patient care away from a generalised model and towards personalised treatments. To complement fast-paced clinical environments, 3D printing technologies must provide sufficiently high throughputs for them to be feasibly implemented. Volumetric printing is an emerging 3D printing technology that affords such speeds, being capable of producing entire objects within seconds. In this study, for the first time, rotatory volumetric printing was used to simultaneously produce two torus- or cylinder-shaped paracetamol-loaded Printlets (3D printed tablets). Six resin formulations comprising paracetamol as the model drug, poly(ethylene glycol) diacrylate (PEGDA) 575 or 700 as photoreactive monomers, water and PEG 300 as non-reactive diluents, and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as the photoinitiator were investigated. Two printlets were successfully printed in 12 to 32 s and exhibited sustained drug release profiles. These results support the use of rotary volumetric printing for efficient and effective manufacturing of various personalised medicines at the same time. With the speed and precision it affords, rotatory volumetric printing has the potential to become one of the most promising alternative manufacturing technologies in the pharmaceutical industry.

3D Printing as a Disruptive Technology for the Circular Economy of Plastic Components of End-of-Life Vehicles: A Systematic Review

The automotive industry is frequently associated with high polluting manufacturing systems, which raise concern owing to the current environmental frame. For this reason, new alternative manufacturing technologies with lower environmental impact have been proposed and tested, such as additive manufacturing (AM). Since AM technologies produce almost no waste, they can represent a huge opportunity for the automotive industry to become greener. In this sense, the object of the present review is to explore the challenges and strategies of 3D printing, recycling, and circular economy in the automotive industry. Therefore, to achieve the aim of the study, a systematic review methodology was used in five stages: (1) defining the targets; (2) extraction of papers from Scopus; (3) text mining and corpora text analysis of relevant documents from the platform; (4) identification of the dominant categories of the research topics; and (5) discussion and control of obtained results and provision of recommendations for future studies. The analysis of 14 relevant articles revealed that 3D printing technology represents an opportunity to empower small-scale producers of polymers, recycle ELV materials, and decentralize the supply chains of plastic articles. The possibility to include plastic parts produced by AM technology has been pointed out as an innovative option for car manufacturers. Unfortunately, till the present day, poor information was found in this regard. Findings highlighted the need for strategies to turn polymeric automotive components into more eco-friendly and safer materials, improve the supply chain of polymers, perform sustainability assessments, and reformulate waste policies for ELVs.

Technical evaluation of additive manufacturing technologies for in-situ fabrication with lunar regolith

In-Situ Fabrication and Repair can significantly reduce the construction cost of a permanent Moon base by using additive manufacturing (AM) and exploiting local resources instead of bringing all the required materials from Earth. In this article, we evaluate alternative additive manufacturing technologies for building a lunar base and maintaining it across its lifecycle. We compare alternative 3D-printing techniques, already tested for manufacturing with simulants of lunar regolith, using energy, Earth-deliverables consumption, and compressive strength of the produced samples as figures of merit. Based on our analysis, we conclude that Cement Contour Crafting and Stereo-lithography AM techniques are the most promising solutions for the construction of outdoor lunar infrastructure and small precise parts and instruments, respectively.

Effects of the Manufacturing Chain on the Surface Integrity when Machining Fir Tree Slots with Alternative Manufacturing Processes

The use of materials with increasing thermo-mechanical strengths for turbine disks and new designs inducing filigree geometries bring conventional manufacturing processes to their technical and economical limits. Investigations regarding alternative manufacturing technologies showed advantages compared to conventional broaching with high-speed steel (HSS) cutting tool material. Surface integrity is particularly crucial for the technological evaluation. However, this aspect has not been considered after downstream processes in which the machined surface integrity is modified. Therefore, the surface integrity of Inconel 718 machined by alternative manufacturing processes including wire EDM, ECM and broaching with cemented carbide is investigated after downstream processes, etching and shot peening.

Air‐Pressure‐Assisted Pen‐Nib Printing for 3D Printed Electronics

Abstract3D printed electronics employing direct‐ink‐writing methods are promising alternative manufacturing technologies for realizing structural electronics. The emerging demand for accessible, cost‐effective, and rapid writing calls for novel approaches to print functional components onto nonflat and 3D architectures. This study presents a novel air‐pressure‐assisted pen‐nib printing approach producing electrical and functional components with various material inks on flat and 3D surfaces. Based on the inks’ rheological properties, the ejected ink's quantity through the nib is manipulated via air pressure; thus, the printed line width is controlled. This strategy also achieves the viscosity range extension of printable inks by enabling printing inks that cannot be used in general pen‐based printing. Three functional inks with different rheological properties—Ag catalyst ink for Cu electroless deposition, Ag‐PEDOT:PSS ink, and thermochromic pigment inks are designed. Several electrical and functional components, such as highly conductive Cu interconnects, Cu spiral coils for wireless power transfer receivers, flexible heaters, and matrix data codes based on temperature‐responsive color transitions are demonstrated. Furthermore, parallel printing with a multi‐nib print‐head is demonstrated for improving the printing speed and manufacturing scalability. The authors believe that this novel approach is promising as a manufacturing technique for realizing 3D printed electronics.

Conductive Electrifi and Nonconductive NinjaFlex Filaments based Flexible Microstrip Antenna for Changing Conformal Surface Applications

As the usage of wireless technology grows, it demands more complex architectures and conformal geometries, making the manufacturing of radio frequency (RF) systems challenging and expensive. The incorporation of emerging alternative manufacturing technologies, like additive manufacturing (AM), could consequently be a unique and cost-effective solution for flexible RF and microwave circuits and devices. This work presents manufacturing methodologies of 3D-printed conformal microstrip antennas made of a commercially available conductive filament, Electrifi, as the conductive trace on a commercially available nonconductive filament, NinjaFlex, as the substrate using the fused filament fabrication (FFF) method of AM technology. Additionally, a complete high frequency characterization of the prototyped antenna was studied and presented here through a comparative analysis between full-wave simulation and measurements in a fully calibrated anechoic chamber. The prototyped antenna measures 65.55 × 55.55 × 1.2 mm3 in size and the measured results show that the 3D-printed Electrifi based patch antenna achieved very good impedance matching at a resonant frequency of 2.4 GHz and a maximum antenna gain of −2.78 dBi. Finally, conformality performances of the developed antenna were demonstrated by placing the antenna prototype on five different cylindrical curved surfaces for possible implementation in flexible electronics, smart communications, and radar applications.

Factors for metal additive manufacturing technology selection

PurposeThis paper addresses the most important factors for the selection of additive manufacturing (AM) technology as a method of production of metal parts. AM creates objects by adding material layer by layer based on 3D models. At present, interest in AM is high as it is hoped that AM contributes to the competitiveness of Western manufacturing industries.Design/methodology/approachA literature study is conducted to identify the factors that affect the selection of AM technology. Expert interviews and the best–worst method are used to prioritize these factors based on relative factor weights.FindingsTechnology, demand, environment and supply-related factors are categorized and further mapped to offer a holistic picture of AM technology selection. According to expert assessments, market demand was ranked highest, although market demand is currently lacking.Research limitations/implicationsThe composition and size of the expert panel and the framing of some of the factors in light of previous literature cause validity limitations. Further research is encouraged to differentiate the selection factors for different AM implementation projects.Originality/valueThe paper presents a more complete framework of factors for innovation selection in general and the selection of AM technology specifically. This framework can serve as a basis for future studies on technology selection in the (additive) manufacturing sector and beyond. In addition to AM-specific factor weights, the paper explains why specific factors are important, reducing uncertainty for managers that have to choose between alternative manufacturing technologies.

Surgical Planning of Sacral Nerve Stimulation Procedure in Presence of Sacral Anomalies by Using Personalized Polymeric Prototypes Obtained with Additive Manufacturing Techniques.

Sacral nerve stimulation or sacral neuromodulation involves the implantation of a stimulating electrode lead through the sacral foramina. In patients with anatomical sacral anomalies, it can constitute a challenging procedure due to a lack of common reference points present in the normal anatomy. In this study, we present an innovative application of additive manufacturing for the planning of sacral nerve stimulation techniques and related surgical procedures in complex cases, and we verify that the use of personalized patient models may help to manage the presence of sacral anomalies. The use of two alternative additive manufacturing technologies working with thermoplastic and thermoset polymers, including fused deposition modeling as low-cost alternative and laser stereolithography as industrial gold standard, is compared in terms of viability, precision and overall production costs. They pay special attention to fidelity in terms of the bone microstructure reconstruction, which is necessary for adequately planning electrode insertion. Advantages and limitations of the alternative approaches are discussed and ideas for future developments and for solving current challenges are presented.

Surface integrity and fatigue of non-conventional machined Alloy 718

Alloy 718 is a high-strength, corrosion-resistant nickel chromium-based superalloy frequently used for applications, such as aerospace, marine, nuclear reactor and chemical industries, due to its outstanding inherent properties such as high strength and corrosion resistance at high temperatures together with good creep behaviour.Although, the use of conventional manufacturing processes is prevalent for their use on Alloy 718, alternative manufacturing technologies are gaining importance. This work compares the effects of alternative manufacturing processes, such as Abrasive water jet (AWJ), Wire Electrical Discharge Machining (WEDM) and ultrasound vibration assisted milling (UVAM) with conventional milling during the manufacture of Alloy 718 parts. Surface integrity, hardness, residual stress and fatigue strength obtained from these machining processes have been examined for cutting alloy 718. Results show that both residual stresses and surface roughness are correlated with fatigue strength. UVAM results shown an improvement on the surface integrity of the final workpiece. AWJ and WEDM show poorer results, further work on post-process technologies or process condition selection must be carry out to establish them as an alternative in Alloy 718 cutting operations.

EPA revises industrial safety regulation

The Environmental Protection Agency has reproposed a controversial regulation intended to protect communities, workers, and emergency responders by preventing accidents at chemical plants, refineries, and other facilities that handle large amounts of hazardous and potentially dangerous chemicals. The regulation was issued in the last days of the Obama administration but put on hold last year by incoming EPA Administrator Scott Pruitt. Pruitt’s rewrite removes several provisions pushed by community and worker advocates. It would rescind accident-prevention provisions that require independent root-cause accident investigations, third-party process audits, and consideration of the use of safer alternative manufacturing technologies, according to an EPA summary. It also removes requirements that would have made some plant-supplied information public and provisions for greater emergency response coordination, citing security concerns. Overall, the changes focus on a 25-year-old provision of the Clean Air Act called the Risk Management Program. RMP covers some 12,500 facilities that, according to EPA,

Technology-based assessment of subtractive machining processes for mold manufacture

Due to an increase in quality as well as flexibility demands in current mold manufacture there is a high technology-driven need for a comprehensive evaluation of different process alternatives. Especially surface integrity nowadays plays a key role for achieving the same part functionality especially when different machining alternatives are principally available. Therefore, in this paper different manufacturing processes are compared to each other by the example of a defined mold cavity out of hardened and tempered cold working steel 45NiCrMo16. Boundary conditions are a specified depth and a target surface finish (defined roughness) as typically defined in die and mold industry. Besides conventional Grinding and Sinking EDM also alternative manufacturing technologies like Laser-based machining and Milling are taken into account for the process benchmark. Based on the technological analysis an overview is derived, which also allows an economical assessment of the different machining strategies.

Structural and morphological approach of Co-Cr dental alloys processed by alternative manufacturing technologies

The integration of digitalized processing technologies in traditional dental restorations manufacturing is an emerging application. The objective of this study was to identify the different structural and morphological characteristics of Co-Cr dental alloys processed by alternative manufacturing techniques in order to understand the influence of microstructure on restorations properties and their clinical behavior. Metallic specimens made of Co-Cr dental alloys were prepared using traditional casting (CST), and computerized milling (MIL), selective laser sintering (SLS) and selective laser melting (SLM). The structural information of the samples was obtained by X-ray diffraction, the morphology and the topography of the samples were investigated by Scanning Electron Microscopy and Atomic Force Microscope. Given that the microstructure was significantly different, further differences in the clinical behavior of prosthetic restorations manufactured using additive techniques are anticipated.

Additive Manufacturing of Functional Elements on Sheet Metal

Laser Beam Melting (LBM) process with its advantages of high design flexibility and free form manufacturing methodology is often applied limitedly due to its low productivity and unsuitability for mass production compared to conventional manufacturing processes. In order to overcome these limitations, a hybrid manufacturing methodology is developed combining the additive manufacturing process of laser beam melting with sheet forming processes. With an interest towards aerospace and medical industry, the material in focus is Ti-6Al-4V. Although Ti-6Al-4V is a commercially established material and its application for LBM process has been extensively investigated, the combination of LBM of Ti-6Al-4V with sheet metal still needs to be researched. Process dynamics such as high temperature gradients and thermally induced stresses lead to complex stress states at the interaction zone between the sheet and LBM structure. Within the presented paper mechanical characterization of hybrid parts will be performed by shear testing. The association of shear strength with process parameters is further investigated by analyzing the internal structure of the hybrid geometry at varying energy inputs during the LBM process. In order to compare the hybrid manufacturing methodology with conventional fabrication, the conventional methodologies subtractive machining and state of the art Laser Beam Melting is evaluated within this work. These processes will be analyzed for their mechanical characteristics and productivity by determining the build time and raw material consumption for each case. The paper is concluded by presenting the characteristics of the hybrid manufacturing methodology compared to alternative manufacturing technologies.

Technological and Economical Assessment of Alternative Process Chains for Blisk Manufacture

Due to the increase of blisk (blade integrated disk) demands instead of the conventional fir-tree design in current aero-engine concepts there is a high resource-driven need for a comprehensive evaluation of different process chain alternatives for blisk manufacture. Therefore, in this paper different manufacturing chains consisting of roughing, pre-finishing and finishing/polishing are compared to each other by the example of a HPC-blisk out of Inconel 718. Beside conventional milling and electrochemical machining also alternative manufacturing technologies like wire-based laser cladding, water jet cutting and automated polishing are taken into account. Based on a technological analysis an adaptable methodology is introduced, which allows an independent economical assessment of different process chains regarding e.g. company-specific boundary conditions or different production quantities.

Alternative lightweight materials and component manufacturing technologies for vehicle frontal bumper beam

One of the vehicle subsystem where large advantage is expected in lightweight design is the bumper subsystems. Bumper subsystems are designed to prevent or reduce physical damage to the front or rear ends of passenger motor vehicles during collusion.In this paper, detail design aspects and method of analysis with particular reference to the application of composite materials to automotive front bumper subsystem, crash box and bumper beam. Innovative design of integrated crash box and bumper beam has been considered for better crashworthiness; the proposed solution results to be of great interest also from the points of view of subassembly cost and effective production process.Three materials have been characterized under quasi static and impact tests for this bumper beam application: GMT, GMTex, and GMT-UD. Major parameters, such as impact energy, peak load, crash resistance, energy absorption and stiffness have been taken as evaluation criteria to compare the proposed materials solutions with pultruded and steel solutions. Finally, the results predicted by the finite element analysis have been evaluated and interpreted in comparison with other existing solutions to put in evidence the effectiveness of the proposed innovative materials and design concept solutions.

Justification for the selection of manufacturing technologies: a fuzzy-decision-tree-based approach

In this paper, a developed model for the justification of alternative manufacturing technologies is presented. The approach, based on fuzzy decision trees, provides a methodology capable of identifying patterns within a technology case repository to support the evaluation of manufacturing systems. Experts are highly influential individuals in the decision process; they provide support and guidance when selecting investments. The experience-oriented task is founded on previous cases or an experts’ experience, and therefore difficult to express in a rational form. The concept is based on a number of characteristics of the case-based reasoning, rule induction and expert system theory. Structured around the fuzzy-decision-tree data-mining technique, the framework provides the ability of using regulated case information to act as structured experience for assisting in the decision process. Fuzzy induction extracts formal rules from a set of experience data, and the expert system philosophy computes the experience base of human expertise for problem-solving. A test case indicates the stability of the classification algorithm and verifies the applicability within the domain.

EDM Machining Capabilities of Magnesium (Mg) Alloy WE43 for Medical Applications

Besides high geometrical accuracy medical devices strongly require a good surface integrity of the produced parts. Surfaces should be optimized to reduce friction or to increase cell adhesion for optimal fitting, mechanical stability and biocompatibility to reduce the risk of inflammatory reactions. Therefore surfaces should posses tailored roughness, a closed structure without pores and cracks and should not contain any toxic substances as a result of the machining process. New biomaterials like magnesium alloys for biodegradable orthopaedic implants are very difficult to machine with conventional processes especially for complex and filigree 3D-structures. Therefore, alternative manufacturing technologies are desired and need to be developed. This paper analyzes the capabilities of state-of-the-art EDM process technologies regarding achievable surface integrity.

A nonparametric stochastic procedure for FMS evaluation

Evaluating alternative manufacturing technologies in the presence of multiple performance measures is often a difficult task for the decision maker. It is for this reason that justification and evaluation of flexible manufacturing systems has been receiving significant attention in the manufacturing circles. This paper proposes an innovative framework, which is based on the combined application of data envelopment analysis and nonparametric statistical procedures, for the selection of flexible manufacturing systems. The strengths of this methodology are that it incorporates variability measures in the performance of alternative systems, provides decision maker with effective alternative choices by identifying homogeneous groups of systems, and presents graphic aids for better interpretation of results. The methodology is illustrated through its application on a previously reported data set.

A topological model of limitations in design for manufacturing

Design for manufacturing (DFM) is a methodology that requires the use of specific manufacturing information at all stages of design. The method relies on a collection of informal and often controversial principles that seem to have eluded the benefits of formal analysis. The transition from design to manufacturing can be modeled as a mathematical mapping, and it has been previously shown how the discontinuity of this mapping formally captures the folklore that “small design changes can lead to significantly increased manufacturing cost”. We study the properties of the transition map in the presence of design and manufacturing variations, and show that its continuity is closely related to the structure of design and manufacturing topological spaces. The main result of this paper establishes conditions on these spaces under which design for manufacturing cannot be described by any continuous transition map. In practical terms, our study reveals the limitations of many DFM systems and approaches in their ability to relate design and manufacturing knowledge, and explains these limitations in terms of a basic incompatibility between the underlying design and manufacturing representations. We discuss how our model applies to DFM relative to traditional manufacturing methods (such as casting and stamping) and we speculate what changes might occur for alternative manufacturing technologies (such as electrical discharge machining (EDM), stereolithography, laser machining, and particle deposition).

Special reports

The key environmental issue of the 1980s has been that of the depletion of the stratospheric ozone. The key environmental issue to be addressed in the 1990s will be that of global warming. These head the list of worldwide ecological problems that arise directly from the activities of man. Each industrial sector has an urgent responsibility to increase awareness of such problems within both management and production and to seek to alleviate its impact upon the environment through development of modified or alternative manufacturing technologies. The electronics assembly sector had the opportunity to consider its future in a more environmentally conscious world at the first conference on Electronics Manufacturing and the Environment. This two‐day event was held at the Bournemouth International Centre. It was organised by Vertical Marketing of Wimborne and sponsored by The Department of Trade and Industry, Du Pont, ICI and Multicore Solders, who must take credit for a well organised and splendidly presented conference. The theme of the conference was one particular implication of environmental awareness, namely the elimination of chlorofluorocarbons (CFCs) as a goal of the electronics manufacturing industry. The conference was aimed at addressing ways in which companies can eliminate the use of CFCs, taking into account the moral and financial implications involved as well as the stringent restrictions in CFC production that are about to be imposed.