Conventional Manufacturing Approaches Research Articles

Additively Manufactured Structures for Precise and Robust Mounting of Optical Elements

The design freedom of Additive Manufacturing offers new opportunities for the design of mounting structures of optical systems, which are not feasible for conventional manufacturing approaches, thus opening up new areas of application for optical systems. We use this to develop a fully monolithic mounting structure for precise positioning of the optical elements, while simultaneously increasing their robustness against harsh environmental conditions. We additively manufacture such a mounting structure for an imaging lens and evaluate its optical performance with interferometric measurement of its wavefront, before and after applying a mechanical shock to the entire system. The results indicate a centering accuracy better than 6~µm, both in the initial positioning as well as the subsequent repositioning after a mechanical shock of 15G.

Hybrid manufacturing cost models: Additive friction stir deposition, measurement, and CNC machining

Based on its potential to reduce lead times, hybrid manufacturing, which often includes both additive manufacturing and machining processes, is receiving more attention from manufacturers as they seek to increase their supply chain resilience and efficiency. A new solid-state additive manufacturing, referred to as additive friction stir deposition (AFSD), has shown the potential to become an important process for hybrid manufacturing. To justify the selection of a hybrid manufacturing approach, the cost needs to be estimated for comparison to conventional approaches. Historically, hybrid manufacturing costs have been difficult to estimate due to the complexity and diversity of the manufacturing processes. This paper proposes cost models that include additive friction stir deposition, structured light scanning, milling, and turning, which can be combined in hybrid manufacturing process planning. These cost models are demonstrated in a case study and cost estimates are compared for hybrid and conventional (machining-only) manufacturing approaches. For the selected case, the hybrid manufacturing process cost was $1007.58, while the conventional milling process cost was $833.60. The results of the case study show that both labor and material costs must be considered to make an informed decision between hybrid and conventional manufacturing approaches.

High-throughput printing of combinatorial materials from aerosols

The development of new materials and their compositional and microstructural optimization are essential in regard to next-generation technologies such as clean energy and environmental sustainability. However, materials discovery and optimization have been a frustratingly slow process. The Edisonian trial-and-error process is time consuming and resource inefficient, particularly when contrasted with vast materials design spaces1. Whereas traditional combinatorial deposition methods can generate material libraries2,3, these suffer from limited material options and inability to leverage major breakthroughs in nanomaterial synthesis. Here we report a high-throughput combinatorial printing method capable of fabricating materials with compositional gradients at microscale spatial resolution. In situ mixing and printing in the aerosol phase allows instantaneous tuning of the mixing ratio of a broad range of materials on the fly, which is an important feature unobtainable in conventional multimaterials printing using feedstocks in liquid–liquid or solid–solid phases4–6. We demonstrate a variety of high-throughput printing strategies and applications in combinatorial doping, functional grading and chemical reaction, enabling materials exploration of doped chalcogenides and compositionally graded materials with gradient properties. The ability to combine the top-down design freedom of additive manufacturing with bottom-up control over local material compositions promises the development of compositionally complex materials inaccessible via conventional manufacturing approaches.

Design & manufacturing of cooled immersion tubes for divertor bolometry in Wendelstein 7-X

After the successful Operation phase 1.2b experimental campaign Wendelstein 7-X was upgraded for steady-state operation with pulse duration of 1800s and up to 18 GJ energy input. Heat management in steady-state requires active water-cooling of the in-vessel components, in particular if temperature-stable environments are required for diagnostics such as bolometry. Two new, actively cooled bolometer immersion tubes (IT) with two camera housings (5–7 detector heads each) have been designed and manufactured for W7-X. By installing the two IT in the same module viewing the poloidal plasma cross-section from opposite sides provides a complete coverage with lines of sight. This allows tomographic reconstruction of the plasma radiation, but make accurate knowledge of the diagnostic geometry essential. This makes accurate manufacturing and assembly essential.An additional design challenge in W7-X is the suppression of Electron Cyclotron Resonance Heating (ECRH) stray-radiation as well as undesired particle deposition from plasma deposition, dust and boronization in the interior of the IT. This was realized with a welded sheet metal shell and a shutter system for each IT. In the design of the cooling channel, a high degree of temperature stability in particular for the detector heads was required. This resulted in complex components that were challenging for conventional manufacturing approaches. Selective laser melting might be an improvement for future projects.

Product Design by Additive Manufacturing for Water Environments: Study of Degradation and Absorption Behavior of PLA and PETG.

Additive manufacturing technologies are shifting from rapid prototyping technologies to end use or final parts production. Polymeric material extrusion processes have been broadly addressed with a specific definition of all parameters and variables for all different of technologies approaches and materials. Recycled polymeric materials have been studied due to the growing importance of the environmental awareness of the contemporary society. Beside this, little specific research has been found in product development applications for AM where the printed parts are in highly moisture environments or surrounded by water, but polymers have been for long used in such industries with conventional manufacturing approaches. This work focuses on the analysis and comparison of two different additively manufactured polymers printed by fused filament fabrication (FFF) processes using desktop-size printers to be applied for product design. The polymers used have been a recycled material: polyethylene terephthalate glycol (PETG) and polylactic acid (PLA). Degradation and water absorption behaviors of both materials are presented, analyzed and discussed in this paper, where different samples have been immersed in saturated solutions of water with maritime salt and sugar together with a control sample immersed in distilled water. The samples have been dimensionally and weight-controlled weekly as well as microscopically analyzed to understand degradation and absorption processes that appear in the fully saturated solutions. The results revealed how the absorption process is stabilized after a reduced number of weeks for both materials and how the degradation process is more remarked in the PLA material due to its organic nature.

Nanomaterial Patterning in 3D Printing.

The synergistic integration of nanomaterials with 3D printing technologies can enable the creation of architecture and devices with an unprecedented level of functional integration. In particular, a multiscale 3D printing approach can seamlessly interweave nanomaterials with diverse classes of materials to impart, program, or modulate a wide range of functional properties in an otherwise passive 3D printed object. However, achieving such multiscale integration is challenging as it requires the ability to pattern, organize, or assemble nanomaterials in a 3D printing process. This review highlights the latest advances in the integration of nanomaterials with 3D printing, achieved by leveraging mechanical, electrical, magnetic, optical, or thermal phenomena. Ultimately, it is envisioned that such approaches can enable the creation of multifunctional constructs and devices that cannot be fabricated with conventional manufacturing approaches.

Additive Manufacturing of Optical Quality Germania-Silica Glasses.

Direct ink writing (DIW) three-dimensional (3D) printing provides a revolutionary approach to fabricating components with gradients in material properties. Herein, we report a method for generating colloidal germania feedstock and germania-silica inks for the production of optical quality germania-silica (GeO2-SiO2) glasses by DIW, making available a new material composition for the development of multimaterial and functionally graded optical quality glasses and ceramics by additive manufacturing. Colloidal germania and silica particles are prepared by a base-catalyzed sol-gel method and converted to printable shear-thinning suspensions with desired viscoelastic properties for DIW. The volatile solvents are then evaporated, and the green bodies are calcined and sintered to produce transparent, crack-free glasses. Chemical and structural evolution of GeO2-SiO2 glasses is confirmed by nuclear magnetic resonance, X-ray diffraction, and Raman spectroscopy. UV-vis transmission and optical homogeneity measurements reveal comparable performance of the 3D printed GeO2-SiO2 glasses to glasses produced using conventional approaches and improved performance over 3D printed TiO2-SiO2 inks. Moreover, because GeO2-SiO2 inks are compatible with DIW technology, they offer exciting options for forming new materials with patterned compositions such as gradients in the refractive index that cannot be achieved with conventional manufacturing approaches.

Electrophoretic deposition of LiFePO4 onto 3-D current collectors for high areal loading battery cathodes

Three-dimensional (3-D) current collectors in lithium-ion batteries with high areal loading of cathode materials enables reduced packaging weight and cost compared to planar current collector materials. Here, we demonstrate the use of electrophoretic deposition (EPD) as a route to prepare thick cathode assembles in 3-D scaffolds using LiFePO4 with areal loadings measured from 2 mg/cm2 and up to 20 mg/cm2 in conductive carbon cloth materials. Our findings demonstrate the LiFePO4 cathodes with areal capacity up to ∼2.4 mAh/cm2 and minimal decay (<0.11%) per cycle. This emphasizes EPD as both a technique to overcome the limitations of conventional manufacturing approaches in scaling to 3-D collector architectures for improved cell-level energy density, but also a route to transition away from costly NMP processing toward cheaper, less toxic solvents, such as ethanol as is demonstrated in this study.

To kit or not to kit: Analysing the value of model-based kitting for additive manufacturing

The use of additive manufacturing (AM) for the production of functional parts is increasing. Thus, AM based practices that can reduce supply chain costs gain in importance. We take a forward-looking approach and study how AM can be used more effectively in the production of multi-part products in low to medium quantities. The impact of introducing kitting in AM on supply chain cost is investigated. Kitting approaches are traditionally devised to feed all components belonging to an assembly into individual containers. Where conventional manufacturing approaches are used for kitting, the produced parts pass through inventory and kit preparation steps before being forwarded to the assembly line/station. However, by taking advantage of the object-oriented information handling inherent in the AM process, kitting information can be embedded directly within the digital design data and parts produced in a common build. This model-based kitting practice reduces − even eliminates − the need for a manual kit preparation step and promises additional supply chain benefits. Eight experiments were conducted using laser sintering (LS) to investigate the impact of model-based component kitting on production cost and supply chain cost. The results show that with current state-of-the-art volume packing software, production costs increase with the adoption of kitting. The increased production cost was off-set to different extents by kitting supply chain benefits, including simplified production planning, reduced work-in-progress inventory and elimination of parts fetching prior to assembly. Findings of this research are of interest for manufacturers, service bureaus and practitioners who use AM for low quantity production, as well as developers of AM volume packing and production planning software.

Impact of Total Build Height and Batch Size on Environmental Performance of Electron Beam Melting

Electron beam melting (EBM) is an additive manufacturing technology, which uses electron beam to melt metallic powder layer by layer and build fully dense parts. This technique is applied efficiently in industrial sectors and biomedical engineering. However, understanding on the environmental aspect of this process is still an open question. In this paper, the influence of total build height and batch size on the environmental performance of EBM is particularly investigated. By comparing environmental impacts between EBM combined with finishing machining (EBM + FM) and conventional manufacturing approaches to manufacture a part, the environmental benefit area of (EBM + FM) is also identified.

Atmospheric, Non-Contact and High Speed Electro Chemical Machining Processes for X-Ray Optics

High resolution X-ray focusing optics is critical component in many spatially resolved techniques at many synchrotron facilities, such as micro X-ray fluorescence, micro-diffraction, and micro-spectroscopy. In order for these optics to achieve modern capability goals, they must embody various key performance attributes such as a minimum in spatial resolution, a maximum in focusing efficiency, a practical working distance (no more than a few meters), and ideally robust achromaticity (negligible photon energy dependence). The state of the art in X-ray optics encompasses, among others, diffractive zone plate optics, Kirkpatrick-Baez (K-B) mirrors, and compound refractive lenses (CRLs). Among these, only K-B mirrors provide highly efficient collection of X-ray photons and essentially perfect achromaticity, but require elliptical mirrors of exceptionally precise figure and placement, as well as sub-nanometer smoothness1. In attempting to identify potential advances in X-ray optics beyond this state of the art, one promising solution is the design of single-bounce, axially symmetric mirror optics with parabolic inner profiles capable of focusing x-rays simultaneously in two orthogonal directions, which may overcome the long focal length limitation of KB mirrors. Manufacture of such precise optics as these novel one-bounce mirrors or the traditional K-B mirrors requires highly advanced surface finishing techniques. Silicon is mostly used in this application due to its low CTE, low thermal deformation, low z, high reflectivity, and low radiation adsorption. The conventional manufacturing approaches used to prepare aspherical, low roughness, and high-z coated silicon mirrors, included Ion Beam Figuring, Elastic Emission Machining (EEM), Plasma Machining, Lapping/Polishing2,3. Of these techniques the Plasma and Ion Beam approaches require vacuum atmosphere for processing limiting the size of the components that can be produced. Meanwhile, EEM can achieve better final finishes (up to 1 A) under atmospheric, non-contact conditions, however it is several orders of magnitude slower (0.1 to 0.001 µm/min) than these approaches. Furthermore, contact machining techniques like Lapping/Polishing tend to lead to surface defects that must be removed prior to mirror usage. Therefore, the design of low cost/high speed machining and polishing systems that can form high resolution x-ray focusing optics over large mirror areas is critical for the formation of next generation of x-ray optics. This paper will discuss ongoing efforts by Faraday to design an atmospheric, non-contact, low cost/high speed electrochemical machining process to produce next-generation ellipsoidal x-ray optics via a scalable pulse-reverse electrochemical manufacturing approach. Unlike conventional electrochemical surface finishing processes, the pulse-reverse process does not require low conductivity/high viscosity electrolytes or the addition of hazardous chemical species (like HF) to remove the oxide film associated with electropolishing of passive and strongly passive materials like Si. This paper will focus on the potential of pulse/pulse reverse electrofinishing process to produce optics such as Kirkpatrick-Baez mirrors and compound refractive lenses for X-ray optic technologies being used at synchrotron facilities. In particular, this talk will discuss fundamental processing techniques and the performance observed in ongoing studies. Initial trials of atmospheric, non-contact process demonstrated a material removal rate of 40 µm/h which is 100 times faster than currently used EEM technique. Acknowledgement This material is based upon ‎work supported by the Department of Energy under ‎Award No‎. ‎DE‎-‎ SC0015201. References S. Matsuyama., et.al., “Textbook for hard X-ray focusing with Kirkpatrick-Baez optics.” Online resource: http://cheiron2009.spring8.or.jp/images/PDF/Practicals?16_29XLU.pdf. Accessed 15 Oct 2015. H. Takino., et.al., “ Ultraprecision Machining of Optical Surfaces.” Nikon Corporation.Y. Mori., et.al., “Development of plasma chemical vaporization machining and elastic emission machining systems for coherent X-ray optics.” SPIE 4501, 2001.

Highly stretchable, printable nanowire array optical polarizers.

Designing optical components such as polarizers on substrates with high mechanical deformability have potential to realize new device platforms in photonics, wearable electronics, and sensors. Conventional manufacturing approaches that rely highly on top-down lithography, deposition and the etching process can easily confront compatibility issues and high fabrication complexity. Therefore, an alternative integration scheme is necessary. Here, we demonstrate fabrication of highly flexible and stretchable wire grid polarizers (WGPs) by printing bottom-up grown Ge or Ge/Si core/shell nanowires (NWs) on device substrates in a highly dense and aligned fashion. The maximum contrast ratio of 104 between transverse electric (TE) and transverse magnetic (TM) fields and above 99% (maximum 99.7%) of light blocking efficiency across the visible spectrum range are achieved. Further systematic analyses are performed both in experimental and numerical models to reveal the correspondence between physical factors (coverage ratio of NW arrays and diameter) and polarization efficiency. Moreover, we demonstrate distinctive merits of our approach: (i) high flexibility in the choice of substrates such as glass, plastic, or elastomer; (ii) easy combination with additional novel functionalities, for example, air permeability, flexibility/stretchability, biocompatibility, and a skin-like low mechanical modulus; (iii) selective printing of polarizers on a designated local area.

A Cost and Resource Consumption Model for Improving Resource Efficiency of Configurable Roll-to-roll Processing

Roll-to-roll (R2R) processing is the process of creating functional films and printed electronic devices, such as printed RFID and printed lighting, by integrating various large area manufacturing processes into a single manufacturing line. It is poised to be a low-cost and efficient manufacturing technology. However, uncertainty and risk exists for the production of specific products in competition with conventional manufacturing approaches. Therefore, a configurable cost and resource consumption model was developed in order to assess the resource effectiveness of the R2R processing line for a specific product design and to identify areas of improvement. The model considers the technical and parametric relationships in terms of cost, manpower, materials, energy consumption and resource requirements. Using the model, hotspots in the manufacturing line were identified and appropriate recommendations were suggested to minimize resource usage and waste, thereby further reducing the cost of manufacturing and enhancing its commercial viability.

A distributed systems model for estimation of printed circuit board fabrication costs

Newer product development methods in distributed manufacturing environments have been increasing in their popularity and use, serving to provide desirable advantages over conventional manufacturing approaches developed for vertically integrated environments. Manufacturing planning has evolved from materials requirements planning (MRP) through MRP II, JIT, flexible manufacturing and lean manufacturing. While the strategies themselves represent improvement towards meeting current goals when compared with their earlier counterparts, they have brought with them a new and different set of shortcomings. This paper focuses on the distributed manufacturing of printed circuit boards. Issues that arise from the nature of the relationships between the cooperating enterprises are discussed from the viewpoint of overall efficiency of the system. The nature and extent of the information shared is reviewed, and the implications and viability of distributed information systems are discussed. Finally, we present a methodology designed for implementation within an existing framework of distributed manufacturing. This distributed information systems approach serves to integrate the upstream design function with the printed circuit board fabrication function without compromising the proprietary information elements of the individual collaborating enterprises. Preliminary results are presented which serve to highlight the advantages and potential reductions in time-to-market and product costs by improving the responsiveness of the information loop. Further, the methodology achieves reduced design and printed circuit board fabrication costs by taking advantage of specific capabilities of the participating firms.