Manufacturing Considerations Research Articles

Impact Analysis of Pocket Damper Seal Geometry Variations on Leakage Performance and Rotordynamic Force Coefficients Using Computational Fluid Dynamics

In this paper, different notch and partition wall arrangements of a fully partitioned pocket damper seal (FPDS) are investigated using computational fluid dynamics (CFD). The CFD model is derived for a baseline FPDS design reflecting the full sealing configuration with a structured mesh. Steady-state simulations are performed for eccentric rotor position and different operational parameters. The results are validated using experimental cavity pressure measurements. In transient computations, rotor whirl is modeled as a circular motion around an initial eccentricity using a moving mesh technique. Different whirl frequencies are computed to account for the frequency-dependent behavior of damper seals. The stiffness and damping coefficients are evaluated from the impedances in the frequency domain using a fast Fourier transform. The validated model is then transferred to varying designs. In addition to the baseline design, six different notch arrangements with constant clearance ratio were modeled. Moreover, two partition wall design variations were studied based on manufacturability considerations. Predicted leakage as well as frequency-dependent stiffness and damping coefficients are presented and the impact of geometry variations on these parameters is discussed. The results suggest that a single centered notch is favorable and indicate considerably higher effective damping for a design with staggered partition walls. A rounded partition wall design with significantly eased manufacturing reveals good performance.

Including the Effects of Curvature in the Cavity Model and New Manufacturing Considerations for Cylindrical Microstrip Antennas

This letter presents an insightful and significant improvement of the cylindrical cavity model and an experimental methodology to compensate the mechanical bending effects on cylindrical microstrip antennas. In the first part of this letter, by studying analytical and numerical results from a nonradiating resonant rectangular cavity, a new function for the resonant length of the circumferential mode that is governed by the antenna thickness and cylinder radius was determined. In the second part, an experimental methodology is presented to compensate the copper elongation effect due to bending. To validate the proposed techniques, a circularly polarized rectangular microstrip antenna was designed and built to operate at 2.2 GHz with an input impedance of 50 Ω for a metallic cylinder with a radius of 25 cm. The experimental results showed that the new approaches to calculate the circumferential resonant frequency and elongation effect due to bending improved the cylindrical antenna design significantly.

Designing for Big Area Additive Manufacturing

Additive manufacturing (AM), more commonly referred to as 3D printing, is revolutionizing the manufacturing industry. With any new technology comes new rules and guidelines for the optimal use of said technology. Big Area Additive Manufacturing (BAAM), developed by Cincinnati Incorporated and Oak Ridge National Laboratory’s Manufacturing Demonstration Facility, requires a host of new design parameters compared to small-scale 3D printing to create large-scale parts. However, BAAM also creates new possibilities in material testing and various applications in the manufacturing industry. Most of the design constraints of small-scale polymer 3D printers still apply to BAAM. Beyond those constraints, new rules and limitations exist because BAAM’s large-scale system significantly changes the thermal properties associated with small-scale AM. This work details both physical and software-related design considerations for additive manufacturing. After reading this guide, one will have a better understanding of slicing software’s capabilities and limitations, different physical characteristics of design and how to apply them appropriately for AM, and how to take the inherent nature of AM into consideration during the design process.

Lattice Structure Design and Optimization With Additive Manufacturing Constraints

Lattice structures with different desired physical properties are promising for a broad spectrum of applications. The availability of additive manufacturing (AM) technology has relaxed the fabricating limitation of lattice structures. However, manufacturing constraints still exist for AM-fabricated lattice structures, which have a significant influence on the printing quality and mechanical properties of lattice struts. In this paper, a design and optimization strategy is proposed for lattice structures with the consideration of manufacturability to ensure desired printing quality. The concept of manufacturable element is used to link the design and manufacturing process. A meta-model is constructed by experiments and the artificial neural network to obtain the manufacturing constraints. Sizes of struts are optimized by a bidirectional evolutionary structural optimization-based algorithm with these manufacturing constraints. An arm of quadcopter is redesigned and optimized to validate the proposed method. Its result shows that optimized heterogeneous lattice structures can improve the stiffness of the model compared to the homogeneous lattice structure and the original design. Both the Von-Mises stress and the maximum displacement are reduced without increasing the weight of designed part. And by considering the manufacturability constraints, the optimized design has been successfully fabricated by the selected additive manufacturing process. Note to Practitioners-Lattice structures might fail to be fabricated by the additive manufacturing technique if the designed model exceeds the processability of the machine. Our approach has the capability of considering the manufacturing constraints in the design and optimization process. We conducted experiments to investigate the manufacturability and proposed a method that can give the domain of the design variables for a selected manufacturing process. And we also designed an algorithm that can optimize the lattice structure inside the domain of design variables. It ensures that the lattice model can be successfully fabricated by the selected process and the performance is dramatically increased compared to the original design. Engineers can use our approach to optimize the lattice structure automatically without knowing the knowledge of optimization and manufacturability.

Generation of patterned indentations for additive manufacturing technologies

This article proposes a novel approach to generate patterned indentations for different additive manufacturing methodologies. Surface textures have many practical applications in various fields, but require special manufacturing considerations. In addition to conventional manufacturing processes, additive processes have also been utilized in the last decade to obtain textured surfaces. The current design and fabrication pipeline of additive manufacturing operations have many disadvantages in that respect. For instance, the size of the design (CAD) files grows considerably when there are detailed indentations on the surfaces of the artifacts. The presented method, which employs morphological operations on a sequence of binary images representing the cross-sections of the printed artefact, overcomes such problems while fabricating the textured objects. Furthermore, the presented technique could be conveniently implemented using the existing hardware resources of almost any three-dimensional printer.

The unimportance of the reaction H2 + N2O ⇆ H2O + N2: A shock-tube study using H2O time histories and ignition delay times

The hydrogen-nitrous oxide (H2–N2O) system is of paramount importance in safety considerations for nuclear waste management and semiconductor manufacturing. For less-dilute H2–N2O mixtures, a reaction of key importance in determining ignition delay times is the direct reaction between H2 and N2O to give H2O and N2, although this reaction has received only one direct investigation in the work of Kosarev et al. (2007). To examine the importance of the title reaction, new H2O time histories were obtained using a laser absorption technique at 1.39 µm in a mixture of 0.222% N2O/1.778% H2/Ar between 1414 and 1811 K near 1.2 atm. Additionally, the ignition delay time measurements of Kosarev et al. (2007) were repeated using endwall emission and pressure diagnostics. The new datasets show excellent agreement with the predictions of a recent mechanism when the title reaction is reduced by a factor of 30 relative to the work of Kosarev et al. Furthermore, the accurate mechanism predictions of H2–N2O ignition delay time data available in the literature (other than those of Kosarev et al.) were not degraded when the proposed value of k1 = 7.0×1013exp(−16,356/T) was used (k1 in cm3 mole−1 s−1, T in K). This expression for k1 should be viewed as an upper limit on the rate for the title reaction and should make the title reaction negligibly important in future NOx modeling efforts; the true value of k1 is likely even lower than this expression. A factor of 2 uncertainty is assigned to this expression for k1. Finally, it is recommended that the data of Kosarev et al. (2007) be neglected in future mechanism validations as these data appear to be inaccurate, in part due to non-ideal pressure rise effects and choice of emission diagnostic.

Ten guidelines for the design of non-assembly mechanisms: The case of 3D-printed prosthetic hands.

In developing countries, prosthetic workshops are limited, difficult to reach, or even non-existent. Especially, fabrication of active, multi-articulated, and personalized hand prosthetic devices is often seen as a time-consuming and demanding process. An active prosthetic hand made through the fused deposition modelling technology and fully assembled right after the end of the 3D printing process will increase accessibility of prosthetic devices by reducing or bypassing the current manufacturing and post-processing steps. In this study, an approach for producing active hand prosthesis that could be fabricated fully assembled by fused deposition modelling technology is developed. By presenting a successful case of non-assembly 3D printing, this article defines a list of design considerations that should be followed in order to achieve fully functional non-assembly devices. Ten design considerations for additive manufacturing of non-assembly mechanisms have been proposed and a design case has been successfully addressed resulting in a fully functional prosthetic hand. The hand prosthesis can be 3D printed with an inexpensive fused deposition modelling machine and is capable of performing different types of grasping. The activation force required to start a pinch grasp, the energy required for closing, and the overall mass are significantly lower than body-powered commercial prosthetic hands. The results suggest that this non-assembly design may be a good alternative for amputees in developing countries.

Design & Manufacture of a High-Performance Bicycle Crank by Additive Manufacturing

A new practical workflow for the laser Powder Bed Fusion (PBF) process, incorporating topological design, mechanical simulation, manufacture, and validation by computed tomography is presented, uniquely applied to a consumer product (crank for a high-performance racing bicycle), an approach that is tangible and adoptable by industry. The lightweight crank design was realised using topology optimisation software, developing an optimal design iteratively from a simple primitive within a design space and with the addition of load boundary conditions (obtained from prior biomechanical crank force–angle models) and constraints. Parametric design modification was necessary to meet the Design for Additive Manufacturing (DfAM) considerations for PBF to reduce build time, material usage, and post-processing labour. Static testing proved performance close to current market leaders with the PBF manufactured crank found to be stiffer than the benchmark design (static load deflection of 7.0 ± 0.5 mm c.f. 7.67 mm for a Shimano crank at a competitive mass (155 g vs. 175 g). Dynamic mechanical performance proved inadequate, with failure at 2495 ± 125 cycles; the failure mechanism was consistent in both its form and location. This research is valuable and novel as it demonstrates a complete workflow from design, manufacture, post-treatment, and validation of a highly loaded PBF manufactured consumer component, offering practitioners a validated approach to the application of PBF for components with application outside of the accepted sectors (aerospace, biomedical, autosports, space, and power generation).

Integrating Engineering, Manufacturing, and Regulatory Considerations in the Development of Novel Antivenoms.

Snakebite envenoming is a neglected tropical disease that requires immediate attention. Conventional plasma-derived snakebite antivenoms have existed for more than 120 years and have been instrumental in saving thousands of lives. However, both a need and an opportunity exist for harnessing biotechnology and modern drug development approaches to develop novel snakebite antivenoms with better efficacy, safety, and affordability. For this to be realized, though, development approaches, clinical testing, and manufacturing must be feasible for any novel treatment modality to be brought to the clinic. Here, we present engineering, manufacturing, and regulatory considerations that need to be taken into account for any development process for a novel antivenom product, with a particular emphasis on novel antivenoms based on mixtures of monoclonal antibodies. We highlight key drug development challenges that must be addressed, and we attempt to outline some of the important shifts that may have to occur in the ways snakebite antivenoms are designed and evaluated.

Cloud manufacturing as a sustainable process manufacturing route

Cloud Manufacturing (CM) is a service oriented business model to share manufacturing capabilities and resources on a cloud platform. Manufacturing is under pressure to achieve cost and environmental impact reductions, as manufacturing becomes more integrated and complex. Cloud manufacturing offers a solution, as it is capable of making intelligent decisions to provide the most sustainable and robust manufacturing route available. Although CM research has progressed, a consensus is still lacking on the concepts within CM as well as applications and scope beyond discrete manufacturing.The aim of this paper is to demonstrate how CM offers a more sustainable manufacturing future to the industry as a whole, before focusing specifically on the application to process manufacturing (e.g. food, pharmaceuticals and chemicals). This paper details the definitions, characteristics, architectures and previous case studies on CM. From this, the fundamental aspects of the CM concept are identified, along with an analysis of how the concept has progressed. A new, comprehensive CM definition is formulated by combining key concepts drawn from previous definitions and emphasizes CM potential for sustainable manufacturing.Four key methods of how CM increases sustainability are identified: (1) collaborative design; (2) greater automation; (3) improved process resilience and (4) enhanced waste reduction, reuse and recovery. The first two key methods are common to both discrete and process manufacturing, however key methods (3) and (4) are more process manufacturing specific and application of CM for these has yet to be fully realised. Examples of how CM’s characteristics may be utilised to solve various process manufacturing problems are presented to demonstrate the applications of CM to process manufacturing. Waste is an important consideration in manufacturing, with strong sustainability implications. The current focus has been on using CM for waste minimisation; however, process manufacturing offers waste as a resource (valorisation opportunities from diversifying co-products, reuse, recycle and energy recovery). Exploring CM’s potential to characterise and evaluate alternative process routes for the valorisation of process manufacturing waste is considered for the first time. The specific limitations preventing CM adoption by process manufacturers are discussed. Finally, CM’s place in the future of manufacturing is explored, including how it will interact with, and complement other emerging manufacturing technologies to deliver a circular economy and personalised products.

Self-Aligned Double Patterning-Aware Detailed Routing With Double Via Insertion and Via Manufacturability Consideration

In 10nm technology node, self-aligned double patterning (SADP) and triple patterning lithography (TPL) allow us to achieve minimum wiring pitch of around 45nm. While metal layers can be printed by SADP, via layer manufacturing requires TPL to maintain design rules. SADP-aware detailed routing is proposed to ensure decomposability of metal layer patterns. However, its routing solution does not automatically guarantee TPL decomposable via layers. Vias have an inherently low reliability and via failure causes a great yield loss. Double via insertion (DVI) is an effective means to increase yield by reducing via failures. With the restriction of SADP design rules and consideration of TPL decomposability for via layers, DVI becomes a more challenging problem. In this paper, we consider DVI and via layer TPL manufacturability simultaneously in SADP-aware detailed routing. Both spacer-is-metal and spacer-is-dielectric types of SADP are considered. Furthermore, we tackle the TPL-aware DVI in postrouting stage. Both ILP and high-performance heuristic solutions are proposed. The experimental results demonstrate our router can obtain 100% routability and TPL decomposable via layers with reduced dead via count. Meanwhile, compared with the ILP approach to solve TPL-aware DVI problem, the heuristic approach can achieve similar solution quality and significant speedup.

Investigation of wire electric discharge machining of stainless-clad steel for optimization of cutting speed

The use of cladded materials has grown up in manufacturing industry as it provides a blend of properties in end-use applications. However, the cutting of a cladded material is really considered as a challenging task owing to their heterogeneous nature; therefore, it is often subjected to thermal cutting processes like gas cutting or plasma arc cutting. But thermal cutting processes offer poor surface finish and require subsequent finishing operations. Wire electric discharge machining (WEDM) is a competent alternate in terms of surface finish, but this process offers relatively low cutting rates. In this research work, an attempt has been made to evaluate and optimize the cutting performance of WEDM for cutting stainless-clad steel in terms of cutting speed which is one of the most crucial considerations in manufacturing. In addition to the commonly studied WEDM parametric effects, the influence of workpiece orientation, layer thickness of individual layer, wire diameter, and pressure ratio of dielectric fluid on the cutting speed is mainly evaluated. Taguchi’s L18 orthogonal array has been used for experimental design. Optimal combinations of machining parameters to maximize the cutting speed are extracted through various statistical analyses, and it has been found that the proposed optimal set of parameters results into an improvement of about 20% in cutting speed in WEDM of stainless-clad steel. It has also been observed that the individual layer thickness of the cladded material plays a vital role in controlling the cutting speed of WEDM. The contribution of stainless steel layer thickness on cutting speed is found to be two times as compared to the contribution of mild steel layer.

Donor Variability in Growth Kinetics of Healthy hMSCs Using Manual Processing: Considerations for Manufacture of Cell Therapies.

Human mesenchymal stromal cells (hMSCs) are excellent candidates for cell therapy but their expansion to desired clinical quantities can be compromised by ex vivo processing, due to differences between donor material and process variation. The aim of this article is to characterize growth kinetics of healthy baseline "reference" hMSCs using typical manual processing. Bone-marrow derived hMSCs from ten donors are isolated based on plastic adherence, expanded, and analyzed for their growth kinetics until passage 4. Results indicate that hMSC density decreases with overall time in culture (p < 0.001) but no significant differences are observed between successive passages after passage 1. In addition, fold increase in cell number dropped between passage 1 and 2 for three batches, which correlated to lower performance in total fold increase and expansion potential of these batches, suggesting that proliferative ability of hMSCs can be predicted at an early stage. An indicative bounded operating window is determined between passage 1 and 3 (PDL < 10), despite the high inter-donor variability present under standardized hMSC expansion conditions used. hMSC growth profile analysis will be of benefit to cell therapy manufacturing as a tool to predict culture performance and attainment of clinically-relevant yields, therefore stratifying the patient population based on early observation.

Optimization of Assembly Sequence Planning Using Soft Computing Approaches: A Review

Assembly sequence planning (ASP) is an NP-hard problem that involves finding the most optimum sequence to assemble a product. The potential assembly sequences are too large to be handled effectively using traditional approaches for the complex mechanical product. Because of the problem complexity, ASP optimization is required for the efficient computational approach to determine the best assembly sequence. This topic has attracted many researchers from the computer science, engineering, and mathematics background. This paper presents a review of the research that used soft computing approaches to solve and optimize ASP problem. The review on this topic is important for the future researchers to contribute in ASP. The literature review was conducted through finding related published research papers specifically on ASP that used soft computing approaches. This review focused on ASP modeling approach, optimization algorithms and optimization objectives. Based on the conducted review, several future research directions were drawn. In terms of the problem modeling, future research should emphasize to model the flexible part in ASP. Besides, the consideration of sustainable manufacturing and ergonomic factors in ASP will also be the new directions in ASP research. In addition, a further study on new optimization algorithms is also suggested to obtain an optimal solution in reasonable computational time.

Developmental biology in bioartificial tissue design: manufacturing and regulatory considerations.

Developmental biology in bioartificial tissue design: manufacturing and regulatory considerations.

Preparing to witness a multimegawatt motor and adjustable speed drive acceptance test–the basics

Adjustable speed drive (ASD) and motors, if selected as a prime mover for compressors, pumps, extruders, etc. can provide various electro-mechanical benefits to its operators and stakeholders. Their benefits and application considerations have been well documented in past papers and tutorials. However, a successful installation of a multi-megawatt motor and ASD system requires detailed application, engineering, manufacturing, testing and installation considerations. Many times testing is requested by the operator and/or consultant, but navigating the types of tests available, test procedures, plans and how they comply with appropriate standards is often not fully understood. This can lead to surprises, shipment delays, price adders and ultimately the equipment itself not being in compliance with the stated project objectives. This paper attempts to address the factory acceptance testing (FAT) phase of a medium voltage motor and ASD system whether procured separately or as a package. Issues such as type of test selection, specifications, standards, preparation, acceptance criteria, and finally string testing will be covered. This paper serves as a guideline of how one can select, prepare, witness and sign off of a medium voltage motor and ASD test.

Design optimization of the ITER tungsten divertor vertical targets

The shaping of the ITER divertor vertical targets has been refined as a consequence of manufacturing and engineering considerations during the prototype manufacturing activities. In this paper, the optimized ITER divertor design is presented together with design validation by 3D field line tracing calculation and thermo-mechanical analysis by finite element calculations. Furthermore, the reduction of W monoblock armour thickness to 6 mm is also discussed.

Relative bioavailability of carnitine delivered by ruminal or abomasal infusion or by encapsulation in dairy cattle

Two studies were designed to evaluate the relative bioavailability of l-carnitine delivered by different methods in dairy cattle. In experiment 1, 4 Holstein heifers were used in a split-plot design to compare ruminally or abomasally infused l-carnitine. The study included 2 main-plot periods, with infusion routes allocated in a crossover design. Within main-plot periods, each of 3 subplot periods consisted of 4-d infusions separated with 4-d rest periods. Subplot treatments were infusion of 1, 3, and 6 g of l-carnitine/d in conjunction with 6 g/d of arabinogalactan given in consideration of eventual product manufacturing. Doses increased within a period to minimize carryover risk. Treatments were solubilized in 4 L of water and delivered in two 10-h infusions daily. Blood was collected before the start of infusion period and on d 4 of each infusion period to obtain baseline and treatment l-carnitine concentrations. There was a dose × route interaction and route effect for increases in plasma carnitine above baseline, with increases above baseline being greater across all dose levels when infused abomasally compared with ruminally. Results demonstrated superior relative bioavailability of l-carnitine when ruminal exposure was physically bypassed. In experiment 2, 56 lactating Holstein cows (143 ± 72 d in milk) were used in 2 cohorts in randomized complete block designs (blocked by parity and milk production) to evaluate 2 rumen-protected products compared with crystalline l-carnitine. Treatments were (1) control, (2) 3 g/d of crystalline l-carnitine (crystalline), (3) 6 g/d of crystalline, (4) 5 g/d of 40COAT (40% coating, 60% l-carnitine), (5) 10 g/d of 40COAT, (6) 7.5 g/d of 60COAT (60% coating, 40% l-carnitine), and (7) 15 g/d of 60COAT. Treatments were top-dressed to diets twice daily. Each cohort used 14-d and included a 6-d baseline measurement period with the final 2 d used for data and sample collection, and an 8-d treatment period with the final 2 d used for data and sample collection. Plasma, urine, and milk samples were analyzed for l-carnitine. Crystalline and 40COAT linearly increased plasma l-carnitine, and 60COAT tended to linearly increase plasma l-carnitine. Total excretion (milk + urine) of l-carnitine averaged 1.52 ± 0.04 g/d in controls, increased linearly with crystalline and 40COAT, and increased quadratically with 60COAT. Crystalline increased plasma l-carnitine and l-carnitine excretion more than 40COAT and 60COAT. In conclusion, preventing ruminal degradation of l-carnitine increased delivery of bioavailable carnitine to cattle, but effective ruminal protection and postruminal bioavailability is challenging.

Considerations for the bioprocessing, manufacture and translation of extracellular vesicles for therapeutic and diagnostic applications

There is growing interest in the potential and use of extracellular vesicles (EVs) for a range of diagnostic and therapeutic applications. EVs have been shown, in some instances, to mediate the regenerative effects elicited by stem cell therapies. As such, they are being studied to identify the extent to which these extracellular bodies can be employed as a therapeutic entity, and significant R&D activity is underway to further understand their clinical and commercial potential. However, successful translation will first require further characterization and standardization of EV production, as well as addressing some of the major challenges associated with their reproducible manufacture. This includes the capacity to produce EVs at a scale that is both clinically and commercially effective. This article will highlight some of the bioprocessing and manufacturing considerations and challenges associated with the standardized production of EVs.

Strategies for functionally graded lattice structures derived using topology optimisation for Additive Manufacturing

A number of strategies that enable lattice structures to be derived from Topology Optimisation (TO) results suitable for Additive Manufacturing (AM) are presented. The proposed strategies are evaluated for mechanical performance and assessed for AM specific design related manufacturing considerations. From a manufacturing stand-point, support structure requirement decreases with increased extent of latticing, whereas the design-to-manufacture discrepancies and the processing efforts, both in terms of memory requirements and time, increase. Results from Finite Element (FE) analysis for the two loading scenarios considered: intended loading, and variability in loading, provide insight into the solution optimality and robustness of the design strategies. Lattice strategies that capitalised on TO results were found to be considerably (∼40–50%) superior in terms of specific stiffness when compared to the structures where this was not the case. The Graded strategy was found to be the most desirable from both the design and manufacturing perspective. The presented pros-and-cons for the various proposed design strategies aim to provide insight into their suitability in meeting the challenges faced by the AM design community.