Additive Manufacturing

Investigating the multidimensional integration between different microbiological kingdoms possesses potential toward engineering next-generation bionic architectures. Bacterial and fungal kingdom exhibits mutual symbiosis that can offer advanced functionalities to these bionic architectures. Moreover, functional nanomaterials can serve as probing agents for accessing newer information from microbial organisms due to their dimensional similarities. In this article, a bionic mushroom was created by intertwining cyanobacterial cells with graphene nanoribbons (GNRs) onto the umbrella-shaped pileus of mushroom for photosynthetic bioelectricity generation. These seamlessly merged GNRs function as agents for mediating extracellular electron transport from cyanobacteria resulting in photocurrent generation. Additionally, three-dimensional (3D) printing technique was used to assemble cyanobacterial cells in anisotropic, densely packed geometry resulting in adequate cell-population density for efficient collective behavior. These 3D printed cyanobacterial colonies resulted in comparatively higher photocurrent (almost 8-fold increase) than isotropically casted cyanobacteria of similar seeding density. An insight of the proposed integration between cyanobacteria and mushroom derives remarkable advantage that arises from symbiotic relationship, termed here as engineered bionic symbiosis. Existence of this engineered bionic symbiosis was confirmed by UV− visible spectroscopy and standard plate counting method. Taken together, the present study augments scientific understanding of multidimensional integration between the living biological microworld and functional abiotic nanomaterials to establish newer dimensionalities toward advancement of bacterial nanobionics.

Standard fused filament fabrication (FFF)-based 3-D printers fabricate parts from thermopolymers, such as polylactic acid (PLA). A new range of metal based PLA composites are available providing a novel range of potential engineering materials for such 3-D printers. Currently, limited material data, specifically thermal property characterization is available on these composites. As a result, the application of these materials into functional engineered systems is not possible. This study aims to fill the knowledge gap by quantifying the thermal properties of copperFill, bronzeFill, magnetic iron PLA, and stainless steel PLA composites and provide insight into the technical considerations of FFF composite 3-D printing. Specifically, in this study the correlation of the composite microstructure and printing parameters are explored and the results of thermal conductivity analysis as a function of printed matrix properties are provided. Considering the relative deviation from the filament raw bulk analysis, the results show the printing operation significantly impacts the resultant component density. Experimentally collected thermal conductivity values, however, do not correlate to the theoretical models in the literature and more rigorous quantitative exercises are required to determine true percent porosity to accurately model the effect of air pore volume fraction on thermal conductivity. Despite this limitation, the thermal conductivity values provided can be used to engineer thermal conductivity into 3-D printed parts with these PLA-based composites. Finally, several high-value applications of such 3-D printed materials that look metallic, but have low thermal conductivity are reviewed.

"Technical progress in the open-source self replicating rapid prototyper (RepRap) community has enabled a distributed form of additive manufacturing to expand rapidly using polymer-based materials. However, the lack of an open-source metal alternative and the high capital costs and slow throughput of proprietary commercialized metal 3-D printers has severely restricted their deployment. The applications of commercialized metal 3-D printers are limited to only rapid prototyping and expensive finished products. This severely restricts the access of the technology for small and medium enterprises, the developing world and for use in laboratories. This paper reports on the development of a <$2000 open-source metal 3-D printer. The metal 3-D printer is controlled with an open-source micro-controller and is a combination of a low-cost commercial gas-metal arc welder and a derivative of the Rostock, a deltabot RepRap. The bill of materials, electrical and mechanical design schematics, and basic construction and operating procedures are provided. A preliminary technical analysis of the properties of the 3-D printer and the resultant steel products are performed. The results of printing customized functional metal parts are discussed and conclusions are drawn about the potential for the technology and the future work necessary for the mass distribution of this
technology."

In order to assist researchers explore the full potential of distributed recycling of post-consumer polymer waste, this article describes a recyclebot, which is a waste plastic extruder capable of making commercial quality 3-D printing filament. The device design takes advantage of both the open source hardware methodology and the paradigm developed by the open source self-replicating rapid prototyper (RepRap) 3-D printer community. Specifically, this paper describes the design, fabrication and operation of a RepRapable Recyclebot, which refers to the Recyclebot's ability to provide the filament needed to largely replicate the parts for the Recyclebot on any type of RepRap 3-D printer. The device costs less than $700 in mate rials and can be fabricated in about 24 h. Filament is produced at 0.4 kg/h using 0.24 kWh/kg with a diameter ±4.6%. Thus, filament can be manufactured from commercial pellets for <22% of commercial filament costs. In addition, it can fabricate recycled waste plastic into filament for 2.5 cents/kg, which is <1000X commercial filament costs. The system can fabricate filament from polymers with extrusion temperatures <250 °C and is thus capable of manufacturing custom filament over a wide range of thermopolymers and composites for material science studies of new materials and recyclability studies, as well as research on novel applications of fused filament based 3-D printing.

One of the key advantages of additive manufacturing (AM) is its digital thread, which allows for rapid communication, iteration, and sharing of a design model and its corresponding physical representation. While this enables a more efficient design process, it also presents opportunities for cyber-attacks to impact the physical word. In this paper the authors examine potential attack vectors along the Additive Manufacturing process chain. Specifically, the effects of cyber-physical attacks, and potential means for detecting them, are explored. Based on the results of this study, recommendations are presented for preventing and detecting cyber-physical attacks on AM processes.

Advanced manufacturing approaches, including additive manufacturing (i.e., " 3D printing ") of metallic structures requires a change to qualification strategies. One approach, informed qualification, integrates modeling strategies to make predictions of material characteristics, including the prediction of tensile properties for given chemistries and microstructures. In this work, constitutive equations are developed and presented that can predict the yield strength of additively manufactured Ti-6Al-4V subjected to one of three different heat-treatments: a stress relief anneal in the aþb phase field; a hot isostatic press treatment in the aþb phase field; and a b-anneal. The equations are nominally identical, though different strengthening mechanisms are active according to subtle microstructural differences. To achieve an equation that can predict the yield strength of the material, it is also necessary to include an assessment of dramatic reduction in the tensile strength due to texture (i.e., a " knock-down " effect). This has been experimentally measured, and included in this paper. The resulting predictions of yield strength are generally within 5% of their experimentally measured values.

The COVID-19 pandemic has caused a surge of demand for medical supplies and spare parts, which has put pressure on the manufacturing sector. As a result, 3D printing communities and companies are currently operating to ease the breakdown in the medical supply chain. If no parts are available, 3D printing can potentially be used to produce time-critical parts on demand such as nasal swabs, face shields, respirators, and spares for ventilators. A structured search using online sources and feedback from key experts in the 3D printing area was applied to highlight critical issues and to suggest potential solutions. The prescribed outcomes were estimated in terms of cost and productivity at a small and large scale. This study analyzes the number and costs of parts that can be manufactured with a single machine within 24 h. It extrapolates this potential with the number of identical 3D printers in the world to estimate the global potential that can help practitioners, frontline workers, a...

Fidelity is one of the most important parameters to consider when dealing with prototypes, which affect the related costs and performances. Current literature contributions often rely on generic definitions of Fidelity based on the concept of closeness. However, the review performed in this paper revealed that Fidelity is a more complex concept, which considers (at least) eight main dimensions, mutually interrelated, and potentially characterized by many other potential sub-dimensions. The identified set has been applied to an industrial case study were a real engineering prototype has been assessed in terms of Fidelity. In particular, the case study application shows how the different dimensions can be interrelated each other. Furthermore, some important research hints have been highlighted in this paper, where the identified set of Fidelity dimensions paves the way for the related future activities.

After the earthquake and tsunami occurred in Chile on February 27th 2010, the Technical University Federico Santa Maria was asked to contribute with reconstruction proposals for the commercial infrastructure destroyed in the town “San Juan Bautista”. Located 600 km (~370 mi) away from the continent, this town is not just the home of several endemic species, but is also located next to a National Protected Area and UNESCO Biosphere Reserve. Within this context, the design problem consisted on the development of a component-based strategy and prefabrication requirements, and to reduce to the minimum the implied logistics and environmental impacts of the new buildings. With a Studio of 23 final year students and the support of the Architecture Firms Association, 11 projects were developed using digital tools such as visual programming and digital fabrication. Finally, technical documentation was produced and delivered to the local and government authorities.

Design for additive manufacturing is adopted to help solve problems inherent to attaching active personal sampler systems to workers for monitoring their breathing zone. A novel and parametric 3D printable clip system was designed with an open source Computer-aided design (CAD) system and was additively manufactured. The concept was first tested with a simple clip design, and when it was found to be functional, the ability of the innovative and open source design to be extended to other applications was demonstrated by designing another tooling system. The clip system was tested for mechanical stress test to establish a minimum lifetime of 5000 openings, a cleaning test, and a supply chain test. The designs were also tested three times in field conditions. The design cost and functionalities of the clip system were compared to commercial systems. This study presents an innovative custom-designed clip system that can aid in attaching different tools for personal exposure measurement ...

The present decade has witnessed a huge volume of research revolving around a number of Additive Manufacturing (AM) techniques, especially for the fabrication of different metallic materials. However, fabrication of ceramics and cermets using AM-based techniques mainly suffers from two primary limitations which are: (i) low density and (ii) poor mechanical properties of the final components. Although there has been a considerable volume of work on AM based techniques for manufacturing ceramic and cermet parts with enhanced densities and improved mechanical properties, however, there is limited understanding on the correlation of microstructure of AM-based ceramic and cermet components with the mechanical properties. The present article is aimed to review some of the most commonly used AM techniques for the fabrication of ceramics and cermets. This has been followed by a brief discussion on the microstructural developments during different AM-based techniques. In addition, an overvie...

Conventional direct ink writing uses circular nozzles and, therefore, results in cylindrical strands. 3D printing with non-circular nozzles adds new degrees of freedom to this versatile technology, and allows obtaining structures with higher specific surface area or even introducing concave surfaces in the printed architecture. This is an enticing prospect for countless applications, including tissue engineering, chemical reaction catalysts, water evaporators and electrochemical energy storage devices. Despite this, it has been hardly explored by the 3D-printing community. Herein, we develop for the first time 3D printed structures with complex filament section morphologies using a custom-made modular nozzle and a self-setting ceramic ink. The fast elastic recovery of the ink allows obtaining good shape fidelity in the printed filaments, permitting the creation of intricate surfaces with up to 30% concavity and increasing up to 2.5 times the specific surface area compared to cylindr...

Shaped Metal Deposition (SMD) in additive layered manufacturing technique is a promising alternative to traditional manufacturing used for manufacturing large, expensive metal components with complex geometry in addition to producing free structures by building materials in a layer by layer technique. The present paper is a comprehensive review of the literature and the latest rapid manufacturing technologies of the SMD technique. The aim of this paper is to comprehensively review the most prominent facts that researchers have dealt with in the SMD techniques especially those associated with the cold wire feed. The intent of this study is to review the literature presented on metal deposition processes and their classifications, including SMD process using Wire+ Arc Additive Manufacturing (WAAM) which divides into wire+ tungsten inert gas (TIG), metal inert gas (MIG), or plasma. This literary research presented covers extensive details on bead geometry, process parameters and heat input or arc energy resulting from the deposition process in both cases MIG and Tandem-MIG in SMD process. Furthermore, SMD may be done using Single Wire-MIG (SW-MIG) welding and SMD using Double Wire-MIG (DW-MIG) welding. The present review shows that the method of deposition of metals when using the DW-MIG process can be considered a distinctive and low-cost method to produce large metal components due to high deposition rates as well as reduce the input of high temperature generated during deposition and reduce the distortions. However, the accuracy and surface finish of the MIG-SMD are less as compared to electron and laser …

Fused Depoition Modeling is a type of Additive Manufacturing technology, which has capability to construct final product by mean of adding layer by layer pattern automatically from data generated by Computer Aided Design (CAD) model. This research work focused over the study of effect of process parameters such as infill percentage, Shell wall thickness and extruion temperature with specimen material used as ABS. This Research work includes optimization of the process parameter using statistical method Response Surface Methodology(RSM(and validating parameter's significance using ANOVA. To overcome some of the drawbacks such as time consumption of printing, machine speed, quality of surface, required properties namely strength, thermal and mechanical properties optimization of process parameter is importand. It is also equally important to find out correlation between process parameters and response outcomes required. Hence, it was proposed to carry experimental investigation of FDM process parameters on polymeric materials because polymeric materials are easy to print as well as economical with wide range of application. FDM process is simple process as compared to other processes so on that basis FDM is chosen. In order to carry work methodology, sample specimens prepared according to ASTM standard for tensile test. Results carried out according to performing test to investigate the relationship between parameters and concomitant effect on strength. Major reason for weak strength of FDM processed parts owes to distortion within the layer or between the layers while building the parts due to temperature gradient. The utility of RP parts suggests that it is dependent on various loading conditions and hence needs to be optimized to gain effective practical implications and optimistic improvisation according to requirements.

Flexible and electrically conductive carbon nanotube/thermoplastic polyurethane (CNT/TPU) nanocomposites have been herein fabricated by selective laser sintering (SLS) for the applications of wearable electronics and strain sensors. CNT/TPU nanocomposite powders were systematically developed by a latex-based technique. The effects of CNT content on the SLS processability of nanocomposite powders and the mechanical, electrical, and piezoresistive properties of SLS-printed specimens were investigated. It was found that the CNT improved the electrical conductivity and strain sensing performance of the printed parts, but excessively high CNT content led to high melt viscosity, deteriorated sintering behavior, and hence degraded mechanical properties. The 2.0 wt% CNT/TPU nanocomposite fabricated by SLS exhibited enhanced electrical conductivity (seven orders of magnitude higher than the neat TPU), high piezoresistive sensitivity (gauge factor of 60 at a tensile strain of 20%), and a wide sensing range (0-130% strain). A mathematical model based on the tunneling theory was established to describe and predict the strain sensing performance of the printed nanocomposites. This study provides profound insights into the development of multi-functional nanocomposites by SLS for their applications in flexible strain sensors.

Additive Manufacturing (AM) is a recent and rapidly developing technology, which has brought about significant disruptions in the manufacturing arena. To capture the full spectrum of changes resulting from AM's introduction into the industry, it is not sufficient to look at it just as a disruptive set of technologies but, rather, take a system's approach. It must be noted that the investigation of AM's impacts cannot be limited to an individual actor, but should encompass the whole supply chain to fully consider the relevant changes in strategic as well as tactical decision-making and operations. This paper presents an analytic approach based on Joint Economic Lot Sizing model, and aims at capturing the most significant impacts resulting from the implementation of the AM concept on a two-level supply chain. This assessment of AM from inventory and logistics standpoints is targeted at providing insights into how manufacturers could adapt their supply chains' planning to accommodate new paradigms introduced by AM. A numerical example followed by sensitivity analysis of a real industrial case study is presented to provide evidence for the main findings and further generalise them.

Numerical simulations have recently shown their potential as a robust, cheap and reliable tool for predicting the quality of components produced by metal additive manufacturing (MAM) processes. Despite the advantages of the MAM processes over conventional manufacturing methods, there is still a lack of thorough understanding on how different defects can form and originate during MAM processing. In that respect, advanced numerical techniques recently developed have the ability to predict the occurrence of such defects. These techniques have paved the way to efficiently obtain the optimal processing window for targeted mechanical properties to satisfy the end-use design requirements. The aim of this review paper is hence to present and classify numerical simulations of MAM, not solely based on their length-scale as often seen, but also based on the involved physics, as well as the modeling strategies at both the meso-scale and part-scale. The paper is arranged in the following way: First, literature describing purely conduction-based heat transfer simulations at meso-scale are presented. This is followed by a review of fluid-based simulations of increasing complexity based on the treatment of free surface of the melt pool at meso-scale. Finally, contributions based on different part-scale modeling approaches with a focus on thermo-mechanical behavior are reviewed.

Statement of the problem: On a pressed lithium disilicate restoration, the building up of a wax pattern of the future restoration is a necessary step on the fabrication process. Conventionally, a wax pattern can be produced by handmade or milled procedures; however , the development of additive manufacturing technologies allows a new fabrication method. Purpose: The present study measured the marginal and internal gap of handmade, milled and additive manufactured patterns for an onlay restoration. Material and methods: A preparation of an onlay restoration was made on an extracted mandibular tooth. A definitive cast was fabricated from a conventional silicone impression of the prepared tooth. Three groups were established: handmade (HM), milled (ML) and additive manufactured (AM); 4 specimens per group were obtained. The marginal and internal gap of each pattern was measured on the extracted molar through a computed tomography test. Sixty measurements were done to measure the marginal gap and another 60 measurements were calculated to analyze the internal gap on each pattern on the prepared tooth. A total of 1.440 measurements were completed. Mann-Whitney and Turkey statistical tests were used for pairwise comparison. Results: The mean of the marginal and internal gap was of 67.56 ± 6.08 μm and 80.62 ± 3.26 μm for the HM group, 85.28 ± 2.17 μm and 96 ± 1.97 μm for the ML group and 86.49 ± 1.74 μm and 91.86 ± 2.88 μm for the AM group, respectively. The HM group presented significantly lower marginal (p=0.029) and internal (p=0.029) gap compared to the ML and AM groups. There was no statistical significant difference (p=0.486) on the marginal gap between the ML and the AM groups, but the AM group, showed significantly (p=0.029) smaller internal gap than the ML group. Conclusions: All the groups presented less than 100 μm marginal and internal gap, which is considered clinically acceptable. Clinical implications: The three fabrication processes are viable options for manufacturing patterns for lithium disilicate onlay restorations, but the best marginal and internal fit was still obtained by the conventional handmade procedures.

The digital workflow - from the intraoral scanning, through the CAD design of the facially generated diagnostic digital wax-up, to the CAD-designed and 3D-printed silicone index with the diagnostic mock-up - provides a new approach that avoids the conventional manufacturing of casts. The development of the process requires a synchronized workflow and good communication between the dental technician, prosthodontist, and patient. This report describes a protocol for the diagnostic digital sequence for the treatment planning of an esthetic rehabilitation.

Additive manufacturing (AM), also known as 3D printing, is gaining enormous importance in the production of highly customised quality and lightweight products in low quantities. In addition to AM's use in producing fully functional industrial components, it is also seen as a technology of the future that will enable civilisation in space. Although the cost structures for AM facilities have been sufficiently studied in the literature, no effort has been made to investigate the scheduling problem of AM machines with the aim of optimising processing time-related performance measures. This paper focuses on the scheduling problem of single and multiple AM machines and proposes mathematical models for optimisation. Mixed-integer linear programming models allocate parts into jobs to be produced on AM machines to minimise makespan. The problem was handled by considering different machine configurations (i.e. single machine, parallel identical machines, and parallel non-identical machines). The models were coded in IBM ILOG CPLEX Optimization Studio (v12.8.0) and solved through the CPLEX solver. This paper presents detailed solutions for numerical examples. A comprehensive computational study was also conducted, and the results are presented. The optimum solutions are reported for most problems. The best solutions obtained within the time limit (i.e. 1800 and 2400 s) are reported for the parallel identical and non-identical AM machine scheduling problems if optimum solution could not be verified.

What effect will new manufacturing technologies like 3-dimensional (3D) printing have on emerging markets? The latest research by Senior Fellow Bryane Michael finds that emerging markets like India will probably see a net positive effect. China will almost certainly lose out during the next wave of manufacturing. It is likely that upper-income, OECD countries – particularly Germany, the U.S., and Japan – will continue producing high-value goods. Because these economies have a strong skilled labor and service-based orientation, they will be able to respond quickly to additive manufacturing. Additive manufacturing, meaning, printing products, will disrupt the old, low-wage, supply-chain-driven approach to cost competition and economic development. Roughly one third of all manufacturing subsectors will undergo radical change as a result of additive manufacturing.

— This work addresses the analysis and development of computationally efficient distortion prediction numerical methodologies applicable to powder bed based selective laser melting (SLM) process. Initially, state of the art of simplified distortion modelling methodologies based on finite element (FE) models is introduced. Existing methodologies are described in terms of complexity and applicability to SLM process. The methodology known as inherent shrinkage, previously developed for multipass welding processes, is applied to predict SLM process induced distortion in Inco 718 testing geometry (cantilever). An assessment about predictive capability of this simplified model based on correlation between numerical results and experimental measurements is performed. Experimental distortions are measured after cutting of base plate connected supports. Initially, the influence of meshing, layer activation and equivalent thermal loads is investigated in terms of prediction capability and computational cost. Subsequently, isotropic and non-isotropic thermal expansion coefficients (α) are considered in the FE-model definition. Results demonstrate that it is feasible to accurately predict the distortion induced by different scanning strategies (chessboard pattern, transversal stripes and longitudinal stripes) in short times. Current developments entail a cost-effective alternative for controlling and reducing distortions in SLM parts.

Purpose - The goal of this study is to evaluate the energy consumed to fabricate nylon parts using selective laser sintering (SLS) and to compare it with the energy consumed for injection molding (IM) the same parts.

Design/methodology/approach - Estimates of energy consumption include the energy consumed for nylon material refinement, adjusted for SLS and IM process yields. Estimates also include the energy consumed by the SLS and IM equipment for part fabrication and the energy consumed to machine the injection mold and refine the metal feedstock required to fabricate it. A representative part is used to size the injection mold and to quantify throughput for the SLS machine per build.

Findings - Although SLS uses significantly more energy than IM during part fabrication, this energy consumption is partially offset by the energy consumption associated with production of the injection mold. As a result, the energy consumed per part for IM decreases with the number of parts fabricated while the energy consumed per part for SLS remains relatively constant as long as builds are packed efficiently. The crossover production volume, at which IM and SLS consume equivalent amounts of energy per part, ranges from 50 to 300 representative parts, depending on the choice of mold plate material.

Research limitations/implications - The study is limited to material refinement and part fabrication and does not consider other aspects of the life cycle, such as waste disposal, distributed manufacturing, transportation, recycling or use. Also, the crossover volumes are specific to the representative part and are expected to vary with part geometry.

Originality/value - The results of this comparative study of SLS and IM energy consumption indicate that manufacturers can save energy using SLS for parts with small production volumes. The comparatively large amounts of nylon material waste and energy consumption during fabrication make it inefficient, from an energy perspective, to use SLS for higher production volumes. The crossover production volume depends on the geometry of the part and the choice of material for the mold.

Wire + arc additive manufacturing (WAAM) is a versatile, low-cost, energy-efficient technology used in metal additive manufacturing. This WAAM process uses arc welding to melt a wire and form a three-dimensional (3D) object using a layer-by-layer stacking mechanism. In the present study, a Ni-based superalloy wire, i.e., Inconel 625, is melted and deposited additively through a cold metal transfer (CMT)-based WAAM process. The deposited specimens were heat-treated at 980 °C (the recommended temperature for stress-relief annealing) for 30, 60, and 120 min and then water quenched to investigate the effect of heat treatment on microstructure and phase transformation and to identify the optimum heat treatment condition. Microstructural results show that the heat treatment, in general, eliminates the brittle Laves phases regardless of the time without changing the grain morphology. However, an increment in the amount of the delta phase is observed with the longer heat treatment periods. Additionally, the size of MC (metal carbide) of Nb is also observed to increase with heat treatment time. This study provides an in-depth understanding of the correlation between heat treatment time and microstructure in additively manufactured Inconel 625, which can facilitate determining the optimum heat treatment condition in a later study.

Laser powder bed fusion additive manufacturing is used for demanding applications in industries such as aerospace. However, machine-specific, optimized process conditions and parameters are required to assure consistent part quality. In addition, differences in supplied powder can cause variation in the mechanical properties of the final parts. In this paper, the variability in mechanical properties of 316L stainless steel produced with two different laser powder bed fusion machines from two different powder batches was studied by producing an identical set of tensile and impact toughness test specimens. The samples were subjected to stress-relieving, solution annealing and hot isostatic pressing to assess the effectiveness of standardized heat-treatments in reducing variation in the mechanical properties of the built parts. Porosity, microstructure, tensile properties, and impact toughness of the specimens were measured to study the effect of changing the material, machine, and heat treatment. The maximum differences observed between the studied machine-powder combinations were approximately 7% for tensile properties and approximately 20% for impact toughness. HIP reduced the variability in all other studied properties except elongation. All the specimens fulfil the minimum requirements set in ASTM F3184-16 for AM 316L.

The aim of this study was to describe systematically the best available evidence of Additive manufacturing (AM) technology for different casting paths and How Rapid Investment casting (RIC) is revolutionizing the field of casting. The objective of this systematic review is to investigate the capabilities and effectiveness of Additive Manufacturing to provide an effective solution for investment casting production. Google Scholar, ResearchGate, Mendeley, ScienceDirect databases are used for research purposes. The conventional method of Investment Casting is less effective in terms of cost and time to develop new hard tooling wax patterns for low volume production and prototypes. To overcome this problem, we introduced additive manufacturing for making patterns for investment casting. This paper reviews the specific applications of Rapid prototyping in the field of casting. After applying the inclusion criteria, we found 40 articles for reviewing. This study concluded that using Additive manufacturing in Investment casting in place of the conventional method is more cost-effective and time-efficient.

Additive Manufacturing, popularly known as “3D printing”, is a manufacturing process based on overlapping of flat layers in order to build a physical object. The data for building this object comes from a 3D model, usually represented by a triangle mesh. One of the first stages in this process is to slice the triangle mesh, resulting in 2.5-D contours, representing each one of the layers of the object. There are many strategies for slicing meshes, however most of the current literature is concerned with ad hoc issues such as the quality of the model, specific improvements in the slicing process and memory usage, whereas none of them addresses the problem from an algorithmic complexity perspective. While current algorithms for slicing run on O(n2 + k2) or O(n2 + n log nk') for n triangles and k planes, the algorithm proposed in this paper runs on O(nk'), where k' is the average number of slices cutting each triangle, what is asymptotically the best that can be achieved under certain common assumptions.

The street system is an important component of the city ontology created for a generative urban design tool and should be able to integrate the many visions or interpretations that designers or other urban design agents may have about streets. This paper describes several characteristics of the street system, with its components organized into object classes which are the shape sets of algebras used by a generation module to generate street network representations that can be assessed by a GIS platform.

Purpose – The purpose of this paper is to present a custom-built tribometer that mimics the wear of additive manufactured fixtures used in inspection of sheet metal components. Design/methodology/approach – Referring to the inspection of sheet metal parts, the fixture undergoes sliding wear during loading and unloading phases of the quality control operation. A new wear test is proposed to mimic the actual wearing conditions of the fixtures because the standards are deemed insufficient. In the tribometer, a cylindrical Alumide cantilever beam is made to slide back and forth inside a slightly bigger hole cut into a nickel-plated steel sheet. The sheet is spring loaded such that it applies a force on the specimen. The wear on the beam is measured after every 500 cycles of the beam motion. Findings – Results of some first test trials are reported to evaluate the durability of Alumide fixtures fabricated by selective laser sintering. The results are also compared to those obtained for a...

Additive manufacturing offers an exclusive way of anisotropic microstructure control with a high degree of freedom regarding variation in process parameters. This study demonstrates a unique texture formation in Inconel 718 (IN718) using a bidirectional laser scan in a laser powder bed fusion (LPBF) process for tailoring the mechanical properties. We developed three distinctive textures in IN718 using LPBF: a single-crystal-like microstructure (SCM) with a < 110 > orientation in the build direction (BD), crystallographic lamellar microstructure (CLM) with a < 110 >-oriented main layer and < 100 >-oriented sub-layer in the BD, and polycrystalline with a weak orientation. The microstructure observations and finite element simulations showed that the texture evolution of the SCM and CLM was dominated by the melt-pool shape and related heat-flow direction. The specimen with CLM exhibited a simultaneous improvement in strength and ductility owing to the stress-transfer coefficient between the < 110 >-oriented main and < 100 >-oriented sub-grains, showing superior mechanical properties compared to cast-IN718. This behavior is largely attributed to the presence of the boundary between the main and sub-layers (crystallographic grain boundary) lying parallel to the BD uniquely formed under the LPBF process. Furthermore, the strength-ductility balance of the part with the CLM can be controlled by changing the stress-transfer coefficient and the Schmidt factor through an alteration of the loading axis. Control of the crystallographic texture, including the CLM formation, is beneficial for tailoring and improving the mechanical performance of the structural materials, which can be a promising methodology.

The brand new Hybrid Manufacturing technologies is providing much more capability to improve and facilitate the manufacturing of metallic parts that requires special standards, complex shape and higher specifications that can‘t be easily manufactured by convectional manners of manufacturing or it‘s very expensive and time consuming to manufacture these parts using the conventional method at high production rate. The combination of more than one manufacturing technologies in one manufacturing method is called Hybrid Manufacturing Technology. Furthermore, when we combine one of the additive manufacturing with another one or more manufacturing process the resulted process is called Hybrid Additive Manufacturing process. One of the most widely used processes of hybrid additive manufacturing is Hybrid Wire-Arc Additive Manufacturing process which is our main subject that is covered throughout this article. This technology uses wire-arc additive manufacturing WAAM as one of the processes combined together within the scope of the hybrid system. In this article we are going to know more about the hybrid system in manufacturing and about the additive manufacturing technologies in brief. Moreover, within the scope of this article we will learn more about WAAM technology in terms of the classification of this method, the types of materials used for it, the defect that may take place in the part during the usage of this technology and the methods and techniques used in order to improve the final product.

In this paper focuses on vibration characteristics of turbine blade made up of isotropic and orthotropic (composite) material. The whole research is been carried out in two phases i.e. modeling and modal analysis. Firstly in modeling phase the blade is modeled by using CREO in such as way that parametric analysis can be done and in second phase i.e. analysis the blade is subjected to a cantilever mode and the natural frequency is been computed.Moreover, a comparative analysis between the blade material natural frequencies has been done also with the presence of cutout of different shapes such as circle and rectangle having same volume and mode shapes is generated and reveals the effect of cutout shapes factor in over all stability of turbine blade.