Showing papers in "Manufacturing letters in 2020"
TL;DR: This paper synthesizes the different perspectives that have been reported on the digital twin to identify the key characteristics that must be understood when developing a digital twin for a specific use case.
Abstract: Digital twin has the potential to be an important concept for achieving smart manufacturing. However, there remains a lot of confusion about the concept and how it can be implemented in real manufacturing systems, especially among small-to-medium-sized enterprises. This paper synthesizes the different perspectives that have been reported on the digital twin to identify the key characteristics that must be understood when developing a digital twin for a specific use case. Example applications are provided and the need for a standardized framework, such as the one under development as ISO 23247 (Digital Twin Manufacturing Framework), is motivated. This framework can enable context-dependent implementations and promote composability and reusability of digital twin components.
117 citations
TL;DR: The capability of cold-spray technique to generate antiviral copper coating on the existing touch surface eliminates the need for replacing the entire touch surface application with copper material, and with a short manufacturing time to produce coatings, the re-deployment of copper-coated parts can be accomplished in minutes, thereby resulting in significant cost savings.
Abstract: In this work, cold-spray technique was employed for rapid coating of copper on in-use steel parts. The primary intention was to alleviate the tendency of SARS-CoV-2 (COVID-19) virus to linger longer on touch surfaces that attract high-to-medium volume human contact, such as the push plates used in publicly accessed buildings and hospitals. The viricidal activity test revealed that 96% of the virus was inactivated within 2-hrs, which was substantially shorter than the time required for stainless steel to inactivate the virus to the same level. Moreover, it was found that the copper-coated samples significantly reduces the lifetime of COVID-19 virus to less than 5-hrs. The capability of the cold-spray technique to generate antiviral copper coating on the existing touch surface eliminates the need for replacing the entire touch surface application with copper material. Furthermore, with a short manufacturing time to produce coatings, the re-deployment of copper-coated parts can be accomplished in minutes, thereby resulting in significant cost savings. This work showcases the capability of cold-spray as a potential copper-coating solution for different in-use parts and components that can act as sources for the spread of the virus.
93 citations
TL;DR: For the first time, the complete composite primary- and morphing-structure of a fixed-wing drone was additively manufactured and was successfully flight-tested, evaluating the potential of combining these two emerging technologies.
Abstract: Continuous carbon fibre composite additive manufacturing opens up new possibilities for automated, cost-effective manufacturing of highly-loaded structures. This is achieved by the high design freedom of the process, allowing to tailor the fibre placement and by thereby fully exploiting the anisotropy and strength of the composite material. On the other hand, compliant or so-called morphing mechanisms – exploiting the elastic properties of the material to achieve shape changes – show great potential in improving the flight performance of aerospace structures. Such structures exhibit complex internal topologies, making them prohibitively expensive to manufacture with conventional processes. Combining additive manufacturing of composites with the utilization of morphing mechanisms has the potential to concurrently reduce manufacturing cost whilst greatly improving the flight performance of aerospace structures. The applicability of composite additive manufacturing to morphing aerospace structures is discussed in this letter. For the first time, the complete composite primary- and morphing-structure of a fixed-wing drone was additively manufactured. The drone was successfully flight-tested, evaluating the potential of combining these two emerging technologies.
73 citations
TL;DR: In this paper, an equimolar AlCoCrFeNi high-entropy alloy (HEA) was synthesized using selective laser melting (SLM) and XRD patterns showed peaks of a single-phase BCC structure typical for a HEA.
Abstract: An equimolar AlCoCrFeNi high-entropy alloy (HEA) was synthesized using selective laser melting (SLM). XRD patterns show peaks of a single-phase BCC structure typical for a HEA. The process parameters were optimized carefully in such a way that a layered microstructure with gaps of controllable size (average size ~67 ± 1 µm) is obtained. The size of the gaps can be controlled using the process parameters and the hatch distance. SLM may be the only process that can process such unique microstructures (linear patterns), where their unique properties may be used as filters in extreme environments like corrosion, temperature, nuclear, etc.
42 citations
TL;DR: The proposed architecture represents an enhanced implementation of the Industry 4.0 decentralized decision concept, enabling a better knowledge and control of system performances to deliver increased profit and response time predictability in highly customised scenarios.
Abstract: The paper presents a novel architecture for production planning and control characterized by a semi-heterarchical structure in which different management levels are identified by both their physical identity and functional scope. The architecture is developed in three management levels: the Knowledge-based Enterprise Resource Planning (the business level, also accountable for cloud interaction); the High-Level Controller (the general performance level); the Low-Level Controller (the operative level). The proposed architecture represents an enhanced implementation of the Industry 4.0 decentralized decision concept, enabling a better knowledge and control of system performances to deliver increased profit and response time predictability in highly customised scenarios.
33 citations
TL;DR: A Human Cyber Physical System (HCPS) framework for Operator 4.0 – Artificial Intelligence Symbiosis is proposed and its main architectural building blocks are described.
Abstract: The emergence of Artificial Intelligence (AI) reveals new opportunities in Industry 4.0 environments. However, the lack of appropriate data and the requirements for trustworthiness pose significant challenges in the applicability and the effectiveness of AI systems in manufacturing environments. On the other hand, Industry 4.0 enables new types of interactions between humans and AI, but also between digital and physical worlds in the context of Cyber Physical Systems (CPS). In this paper, a Human Cyber Physical System (HCPS) framework for Operator 4.0 – Artificial Intelligence Symbiosis is proposed and its main architectural building blocks are described.
32 citations
TL;DR: In this paper, a CNN-based monitoring model achieved a classification accuracy of 96.1% for porosity occurrence detection, though the prediction of micro (less than 100 µm) and deep subsurface pores still remains challenging.
Abstract: A porosity monitoring scheme for laser welding process was developed based on a deep learning approach. The in-process weld-pool data were sensed with a coaxial high-speed camera and labelled with the porosity attributes measured from welded specimens. A convolutional neural network (CNN) model with compact architecture was designed to learn weld-pool patterns to predict porosity. In laser welding experiments of 6061 Aluminum alloy, the CNN-based monitoring model achieved a classification accuracy of 96.1% for porosity occurrence detection, though the prediction of micro (less than 100 µm) and deep subsurface pores still remains challenging.
32 citations
TL;DR: In this article, a new technique was presented to repair the exit-hole of an Al-Mg friction stir welding, without any third body material with inexpensive probeless tooling, inducing forging, stirring, and thermomechanical consolidation of the local spot joint.
Abstract: The exit-hole is one major discontinuities in the friction based processes, where all the volume of the tool’s probe is missing with a depth that corresponds to the full thickness of the processed component. This letter presents a new technique to repair the exit-hole of an Al-Mg friction stir welding, without any third body material with inexpensive probeless tooling, inducing forging, stirring, and thermomechanical consolidation of the local spot joint. Intercalated banned type structures with interpenetrating features were achieved. Composite type mixed structure was obtained at repaired zone with a local tensile strength of 159 MPa.
31 citations
TL;DR: In this paper, a 3D printing based manufacturing method using biomass-fungi composite material is reported, where the biomass is derived from waste agricultural materials and the fungi grow through the biomass and bind the biomass together.
Abstract: This paper reports a 3D printing based manufacturing method using biomass-fungi composite material. The biomass is derived from waste agricultural materials. The fungi grow through the biomass and bind the biomass together. The novel method comprised the preparation of a printable biomass-fungi mixture. After printing, the fungi grew inside the printed sample over a few days. The feasibility of this new method was demonstrated by a preliminary experiment. In comparison to molding based manufacturing processes, 3D printing can facilitate greater flexibility in design and print custom designs for packaging and construction applications.
31 citations
TL;DR: In this paper, a femtosecond laser with a cross-hatching strategy was used to create cone-shaped micro holes with low tip radii in a tool steel mold, which were then used in an injection molding process to replicate polypropylene microneedles.
Abstract: Microneedle arrays are minimally invasive devices which offer a pain free, straightforward and efficient method for transdermal drug delivery. Manufacturing these micro-systems represents a real challenge and a mass production process with high volume outputs at low cost is lacking. In this study, we present a novel method to produce polymer microneedles using laser ablated moulds in an injection moulding process. We successfully created cone-shaped micro holes with low tip radii in a tool steel mould, using a femtosecond laser with a cross-hatching strategy. Finally, the attained mould was used in an injection moulding process to replicate polypropylene microneedles.
30 citations
TL;DR: In this paper, ready-to-print fresh cementitious mixtures with silica fume and superplasticizer were characterized for printability based on their rheological properties.
Abstract: The need to automate the construction process for civil infrastructures has been ceaselessly propelled by the reported number of detrimental site accidents, enormous time, and material wastages in current labor-intensive approaches. Additive 3D printing could revolutionize the construction-site. Notable advantages of concrete 3D printing include wider build customizability, safer work ambiance, reduced construction time and cost. The major challenge in concrete printing is to identify and maintain the mixture characteristics suitable for printing and stacking up in layers. In this study, ready-to-print fresh cementitious mixtures with silica fume and superplasticizer were characterized for printability based on their rheological properties.
TL;DR: A new control approach is proposed which compensates the residual heat through laser power adjustment, and a model called residual heat factor (RHF) is developed to 'quantify' the residualHeat effect, and laser power is controlled proportional to this RHF.
Abstract: Typical scan strategies for laser powder bed fusion (LPBF) additive manufacturing systems apply a constant laser power and scan speed. Localized preheating from adjacent scan paths (residual heat) result in inconsistent melt-pool morphology. A new control approach is proposed which compensates the residual heat through laser power adjustment. A model called residual heat factor (RHF) is developed to ‘quantify’ the residual heat effect, and laser power is controlled proportional to this RHF. Experiments are conducted on a custom-controlled LPBF testbed on nickel-alloy (IN625) bare plate, and the effects of this unique scan strategy are investigated by in-situ melt-pool monitoring.
TL;DR: In this article, the authors demonstrate the potential of laser engineered net shaping (LENS) to fabricate near-eutectic AlxCoCrFeNi2.1 high-entropy alloys from elemental powders.
Abstract: This work demonstrates the potential of laser engineered net shaping (LENS) to fabricate near-eutectic AlxCoCrFeNi2.1 high-entropy alloys from elemental powders. The as-deposited alloys consisted of FCC and B2 phases and revealed a change in microstructure from dendritic to lamellar with an increase in Al-concentration. The strength of the AlxCoCrFeNi2.1 alloys can be expressed as a function of the volume fraction of the constituent phases. Our results suggest that LENS can be readily adapted to large-scale production of these alloys from elemental powders with excellent microstructural homogeneity, printability and mechanical properties, and avoids the use of expensive pre-alloyed powders.
TL;DR: In this article, a relatively dense Cu/25vol% coated-D composite was printed (96%) at an energy density of 1200 J/mm3 (power = 900 W, scan = 12.7 W), and no graphitization of the D.
Abstract: Copper (Cu)/diamond (D) composites have excellent thermal properties but are hard to manufacture with conventional methods. Additive manufacturing (AM) can overcome this issue because of its high degree of freedom to fabricate complex designs. In this letter, we demonstrate the laser directed energy deposition of Cu/D composites. D particles were coated with graded TiO2-TiC interphase to enhance its wettability with molten Cu. A relatively dense Cu/25 vol% coated-D composite was printed (96%) at an energy density of 1200 J/mm3 (power = 900 W, scan = 12.7 mm/s) with high thermal conductivity (330 W/m.K), and no graphitization of the D.
TL;DR: In this paper, the authors proposed to print multifunctional composite materials with 3D continuous carbon fibers by coextrusion, which allowed for direct printing of free-standing compliant carbon fiber reinforced composite structures and composites with conductive channeling.
Abstract: This study proposes to print multifunctional composite materials with 3D continuous carbon fibers. Coextrusion was implemented to deposit continuous carbon fibers simultaneously with doped functional photopolymer resin, subsequently rapidly cured by an ultraviolet laser. The technique allowed for direct printing of free-standing compliant carbon fiber reinforced composite structures and composites with conductive channeling. In particular, a novel functional, full lithium-ion structural battery was successfully printed in one single step with each coated carbon fiber acting as a micro-battery cell. The characterized mechanical and electrochemical performance well demonstrated the potentials of the proposed method in direct printing multifunctional structural composites.
TL;DR: In this article, the influence of the process on Ti-6Al-4V powder, by comparing virgin powder to reused powders over two processing cycles, benchmarking the most sensitive powder characteristics.
Abstract: Electron beam powder bed fusion can offer advantages in terms of powder reuse by virtue of larger layer thickness and flexible recoater, thus lowering the economic barrier by reducing waste. Systematic studies focused on quantifying the effect of reuse on powder performance metrics such as size, rheometry and flowability remain scarce. This work presents results on the influence of the process on Ti-6Al-4V powder, by comparing virgin powder to reused powders over two processing cycles, benchmarking the most sensitive powder characteristics. Particle size, morphology, flow properties and rheometry are compared. It was observed that morphology, size distribution, flowability and spreadability were degraded due to partial sintering and powder recovery.
TL;DR: In this paper, the results demonstrate that the cell walls are strong and interconnected; twin's grains are visible in the cell wall surface in the evaporative process foam specimens and the mechanical properties are higher in foams made by evaporative as compared to the leachable process.
Abstract: Stainless steel foams were fabricated by evaporative and leachable space holder method. The results demonstrate that the cell walls are strong and interconnected; twin’s grains are visible in the cell wall surface in the evaporative process foam specimens. The cell structures and porosities have a significant effect on the mechanical properties. Calculated yield stress and energy absorption of the evaporative and leachable process are in the range of 43.2 to 6.92 & 29.1 to 3.96 MPa and 32.6 to 8.98 & 20.97 to 6.35 MJ/m3. The mechanical properties are higher in foams made by evaporative as compared to the leachable process.
TL;DR: In this article, the authors focused on the manufacturing challenges during microwave curing of carbon fiber reinforced epoxy composite (CFREC) with 10% reinforcement by weight with or without assistance of vacuum pressure.
Abstract: Carbon fiber reinforced epoxy composite (CFREC) have gained interest due to their high strength to weight ratios. Conventional techniques to fabricate carbon fiber composite come with a limitation of overheating, high cycle time and high cost. The present manuscript is focused to address some manufacturing challenges during microwave curing of CFREC with 10% reinforcement by weight. In the present work microwave curing was done with or without assistance of vacuum pressure. The mechanical behavior of the specimens was studied in terms of tensile strength and hardness. The scanning electron microscopy (SEM) was used to analyze the tensile fractured specimens.
TL;DR: In this article, the influence of microwave process parameters such as microwave power and exposure time was studied on mechanical and microstructural feature of polycaprolactone (PCL) composite foam.
Abstract: This research work is aimed to utilize microwave energy for rapid fabrication of nano-hydroxyapatite (nHA) reinforced polycaprolactone (PCL) composite foam. Weight fraction of nHA and NaCl was fixed at 20% and 30%, by weight, respectively. The NaCl was acts as microwave absorber as well as the porogen agent in the composite. The interconnected porosity was induced by leaching of the NaCl particles from composite in an ultrasonicator bath. The influence of microwave process parameters such as microwave power and exposure time was studied on mechanical and microstructural feature of PCL/nHA composite foam.
TL;DR: Light is shed on the prospective adoption and acceptance of VAs to assist the Operator 4.0 during industrial production processes within the Social Smart Factory and on the prototyping of a VA for a CNC milling machine.
Abstract: Greater cognitive task load and growing shortage of high-skilled labor call for new smart interactions between the cyber-physical production system (CPPS) and the Operator 4.0. Voice-enabled Assistants (VA) gives users intuitive access to a plethora of information and knowledge. However, their implementation still finds limited attention in industrial contexts. This article sheds light on the prospective adoption and acceptance of VAs to assist the Operator 4.0 during industrial production processes within the Social Smart Factory. Leveraging on quality-driven engineering of human–machine interaction systems and on the prototyping of a VA for a CNC milling machine, insights and challenges are discussed.
TL;DR: In this paper, the welding performance of adjustable ring mode (ARM) and standard single beam fiber laser was analyzed from a steel welding perspective, and it was shown that applying more power in the ring beam than in the center beam noticeably reduced accumulated spatter on the weld bead and surrounding area.
Abstract: The welding performance of adjustable ring mode (ARM) and standard single beam fiber lasers was analyzed from a steel welding perspective. The ARM laser has the capability of adjusting the distribution of laser power across beams. Thus, the ARM laser enabled an increase of penetration depth and minimized spatter formation. Furthermore, at the same total power, the ARM laser with higher power in the center than in the ring beam increased the depth of penetration in comparison with a standard fiber laser. However, applying more power in the ring beam than in the center beam noticeably reduced the accumulated spatter on the weld bead and surrounding area.
TL;DR: In this paper, a multi-axis coextrusion deposition technique is proposed to fabricate a 3D structural battery composite with continuous carbon fibers coated by solid polymer electrolyte (SPE).
Abstract: There is a growing interest in fabrication of structural battery composites to achieve mass-less energy storage. Additive manufacturing would allow customization of their battery form factor to fit specific needs. In this study, a multi-axis coextrusion deposition technique is proposed to fabricate a 3D structural battery composite with continuous carbon fibers coated by solid polymer electrolyte (SPE). The SPE-coated carbon fibers are coextruded with cathode doped matrix materials. All the printed complex structural battery composites successfully power up LEDs. Further mechanical and electrochemical characterization demonstrates the potentials of the additively manufactured composites in electrical energy storage and load bearing.
TL;DR: In this paper, a low-cost dynamometer for milling force measurement is described, which is based on constrained motion/flexure-based kinematics, where force is inferred from displacement measured using a low cost optical interrupter (i.e., a knife edge that partially interrupts the beam in an emitter-detector pair).
Abstract: This paper describes the design and testing of a low-cost dynamometer for milling force measurement. The monolithic design is based on constrained-motion/flexure-based kinematics, where force is inferred from displacement measured using a low-cost optical interrupter (i.e., a knife edge that partially interrupts the beam in an emitter-detector pair). The time-dependent displacement of the dynamometer’s moving platform caused by the milling force is converted to the frequency domain, multiplied by the inverse of the single degree of freedom frequency response, and converted back to the time domain to obtain the time dependent cutting force. Comparisons with commercially available, piezoelectric-based force measurement are provided.
TL;DR: In this article, a project developed in an Italian shipping company shows the potential of solutions based on these principles and concepts, with higher goods security level and a real-time data sharing policy.
Abstract: Global logistic activities related to e-commerce have become very time dependent in recent years. International couriers face everyday issues related to pick-up time windows, lead times delays, express/normal deliveries management, security and VAT management. There are supply chain management methodologies that, based on lean thinking principles integrated with industry 4.0 concepts, well address these issues. In this paper, a project developed in an Italian shipping company shows the potential of solutions based on these principles and concepts. Main results from this project were lead time reduction and cost reduction, with higher goods security level and a real-time data sharing policy.
TL;DR: An encrypted and federated framework for training diagnosis and prognosis models that would not require sharing data is presented that guarantees the privacy of the data while generates comprehensive models that leverage the variety of multiple enterprises operations.
Abstract: Data security is one of the most important concerns of manufacturing entities. Therefore, enterprises hesitate to share data with third parties for building predictive and prognostic models. In such scenario, building comprehensive models for predicting asset failures is challenging given data from a single enterprise would not include required variety of operation regimes and failure modes. In this article, we present an encrypted and federated framework for training diagnosis and prognosis models that would not require sharing data. The proposed framework guarantees the privacy of the data while generates comprehensive models that leverage the variety of multiple enterprises operations.
TL;DR: In this paper, a cobalt-based sonotrode coating was used to achieve shear strength comparable to bulk 4130 material, but with higher power input promotes metallurgical bonding through softening and increased plastic deformation.
Abstract: Ultrasonic additive manufacturing (UAM) is a solid-state 3D printing technology. Steels can be welded with UAM at reduced ultrasonic power, achieving half the shear strength of bulk material. A higher weld power is demonstrated by using a cobalt-based sonotrode coating, achieving shear strengths comparable to bulk 4130 material. In-situ temperature measurements and fracture surface analyses indicate that higher power input promotes metallurgical bonding through softening and increased plastic deformation. Carbides and ferrite are found at 1 μm scale at key weld interfaces; no martensite is found due to an increase in critical transformation temperatures associated with high heating rates.
TL;DR: Based on the experimental observations made from cross-flow weld configurations, it is proposed that pure Cu should be placed on the retreating and 6061-T6 AA on the advancing sides for obtaining the defect-free weld in dissimilar butt welding as mentioned in this paper.
Abstract: The material mixing in FSW of the dissimilar weld is significantly affected by the local heat partitioning arising from the difference in mechanical and thermal properties at the interface of the tool/soft/hard materials. Based on the experimental observations made from cross-flow weld configurations, it is proposed that pure Cu should be placed on the retreating and 6061-T6 AA on the advancing sides for obtaining the defect-free weld in dissimilar butt welding. For the successful weld obtained based on the suggested sheet positioning, the ultimate tensile strength (UTS) and percentage uniform elongation are 252 MPa and 12.2%, respectively.
TL;DR: In this article, the synthesis and machinability studies for a new TiC ceramic and MoS2 soft particulate reinforced aluminium alloy 7075 (AA7075) matrix composite (AMCs) were presented.
Abstract: In this work, the synthesis and machinability studies are presented for a new TiC ceramic and MoS2 soft particulate reinforced aluminium alloy 7075 (AA7075) matrix composite (AMCs). The results show that the AMCs have improved machinability compared with the base AA7075. The chip morphology is changed from continuous sheared chips in AA7075 to discontinuous chips in AMCs. The change is caused by the reduced ductility in AMCs due to reinforcement TiC and MoS2 microparticles. The surface roughness is increased for the AMCs when compared to that of base alloy due to hard TiC particles.
TL;DR: In this article, the fretting wear resistance of additively manufactured Inconel 625 was studied at room and elevated temperatures, and the results showed a 30% decrease in near-surface mean hardness at 510°C compared to room temperature.
Abstract: Various mechanical systems are subjected to inherent oscillatory motions often paired with extreme, high-temperature environments resulting in fretting wear. In this work, the fretting wear resistance of additively manufactured Inconel 625 was studied at room and elevated temperatures. In-situ temperature-controlled nanoindentation was employed to further elucidate mechanical property evolution as a function of temperature. The results showed a 30% decrease in near-surface mean hardness at 510 °C compared to room temperature. However, the material exhibited significantly lower wear and coefficient of friction values at high temperatures, attributed to the formation of a compacted, intermediate oxide layer preventing excessive friction and wear.
TL;DR: A concept smart manufacturing multiplex capable of executing multiple process chains and thermodynamic pathways to control the geometric, morphological as well as microstructural integrity of custom components is introduced.
Abstract: This letter introduces a concept smart manufacturing multiplex (SMM) capable of executing multiple process chains and thermodynamic pathways to control the geometric, morphological as well as microstructural integrity of custom components. A proof-of-concept based on hybrid machine tools consisting of additive and subtractive processes integrated with high resolution sensors via a novel sensor wrapper to track the spatiotemporal evolution of the process states is implemented. The value of SMM to discrete part manufacturing in realizing low-volume, high variety parts and its ability to handle multiple processing pathways in a single machine is discussed.