Efficient Manufacturing: Materials, Processes, and Systems

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Topic Information

Dear Colleagues,

This topic aims to provide a collection of advances in manufacturing that are driven by current societal, ecological and economical trends requiring ever increasing efficiency, as we are facing urgent challenges of global sustainability. For most goods it is not enough to have simply the ability of their production. But rather the materials, processes and systems used in the production must be as efficient (in resources, energy, time, cost etc.) as possible, to grant access to a large customer base without depleting nature’s resources. A prime example is the production of new energy vehicles, which should have a low resource usage during production and their life cycle but must also be sufficiently affordable to make a positive global impact. The topic includes but is not limited to:

• Material related aspects of scalable and sustainable manufacturing, for example hybrid composite materials and new formulations to conserve or replace scarce resources.
• Manufacturing processes that are energy efficient, offer high thruput or automation capabilities even in small, flexible batches.
• Advanced manufacturing systems that can help to conserve time, material or energy compared to conventional systems by employing intelligent control systems, optimization strategies, resource recovery and the like.

Prof. Dr. Junying Min
Dr. Christopher Ehrmann
Dr. Nan Li
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Designs designs	-	3.2	2017	16.4 Days	CHF 1600
Energies energies	3.2	5.5	2008	16.1 Days	CHF 2600
Materials materials	3.4	5.2	2008	13.9 Days	CHF 2600
Polymers polymers	5.0	6.6	2009	13.7 Days	CHF 2700
Sustainability sustainability	3.9	5.8	2009	18.8 Days	CHF 2400

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Published Papers (24 papers)

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18 pages, 6231 KiB  

Open AccessArticle

Hybrid Convolutional Neural Network Approaches for Recognizing Collaborative Actions in Human–Robot Assembly Tasks

by Zenggui Gao, Ruining Yang, Kai Zhao, Wenhua Yu, Zheng Liu and Lilan Liu

Sustainability 2024, 16(1), 139; https://doi.org/10.3390/su16010139 - 22 Dec 2023

Viewed by 628

Abstract

In the context of sustainable manufacturing, efficient collaboration between humans and machines is crucial for improving assembly quality and efficiency. However, traditional methods for action recognition and human–robot collaborative assembly often face challenges such as low efficiency, low accuracy, and poor robustness. To [...] Read more.

In the context of sustainable manufacturing, efficient collaboration between humans and machines is crucial for improving assembly quality and efficiency. However, traditional methods for action recognition and human–robot collaborative assembly often face challenges such as low efficiency, low accuracy, and poor robustness. To solve such problems, this paper proposes an assembly action-recognition method based on a hybrid convolutional neural network. Firstly, an assembly action-recognition model is proposed using skeletal sequences and a hybrid convolutional neural network model combining Spatial Temporal Graph Convolutional Networks (ST-GCNs) and One-Dimensional Convolutional Neural Networks (1DCNNs) to sense and recognize human behavior actions during the assembly process. This model combines the joint spatial relationship and temporal information extraction ability of the ST-GCN model with the temporal feature extraction ability of the 1DCNN model. By incorporating Batch Normalization (BN) layers and Dropout layers, the generalization performance of the model is enhanced. Secondly, the model is validated on a self-constructed dataset of assembly actions, and the results show that the recognition accuracy of the model can reach 91.7%, demonstrating its superiority. Finally, a digital workshop application system based on digital twins is developed. To test the effectiveness of the proposed method, three sets of control experiments were designed to evaluate both objective and subjective aspects and verify the feasibility of the method presented in this paper. Compared with traditional assembly systems, the proposed method optimizes the recognition of human–robot collaborative assembly actions and applies them to intelligent control systems using digital-twin technology. This intelligent assembly method improves assembly efficiency and saves assembly time. It enables efficient and sustainable collaboration between humans and robots in assembly, leading to a positive and sustainable impact on the manufacturing industry. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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17 pages, 6887 KiB  

Open AccessCommunication

Modification of a Grain Moisture Conditioner into a Vacuum Steam Pasteurizer

by Marlon Galad, Sulaymon Eshkabilov and Ewumbua Monono

Designs 2024, 8(1), 1; https://doi.org/10.3390/designs8010001 - 21 Dec 2023

Viewed by 1267

Abstract

Eliminating microbes in low-moisture foods (LMFs) is challenging because this requires the preservation of their raw quality during pasteurization. Vacuum steam pasteurization (VSP) has been shown to be effective in reducing microbes while maintaining food quality. These studies were conducted at a laboratory [...] Read more.

Eliminating microbes in low-moisture foods (LMFs) is challenging because this requires the preservation of their raw quality during pasteurization. Vacuum steam pasteurization (VSP) has been shown to be effective in reducing microbes while maintaining food quality. These studies were conducted at a laboratory scale where issues such as steam distribution, penetration, and condensation are not a concern, but in larger samples, these are of primary concern. Hence, this study repurposes a pilot-scale grain moisture conditioner (GMC) into a VSP system with the aim of replicating the lab-scale conditions in larger-scale applications. The modification entailed a series of design alterations, conducting a structural analysis of the conditioning chamber, creating a vacuum environment, ensuring uniform steam distribution, and designing and adding a preheater and a cooling system. Performance tests confirmed that the adapted system replicates the VSP’s lab-scale functionality. The results demonstrated that the VSP system can preheat to beyond 40 °C and achieve an absolute pressure of 11.7 kPa at 85 °C with a 344.7 Pa pressure increase per minute. Furthermore, steam distribution inside the chamber showed no significant variations, and rapid steam evacuation and chamber cooling could be performed simultaneously. The success of these modifications will be used in future experiments. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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12 pages, 2829 KiB  

Open AccessArticle

Effects of 3D Printing Parameters on Mechanical Properties of ABS Samples

by Mohd Nazri Ahmad and Abdullah Yahya

Designs 2023, 7(6), 136; https://doi.org/10.3390/designs7060136 - 24 Nov 2023

Cited by 2 | Viewed by 1983

Abstract

The most modern technique utilized to create intricate manufactured parts for a variety of applications is called additive manufacturing (AM). Fused deposition modeling (FDM) has been acknowledged as the greatest consideration in the development and industrial sectors. The main objective of this study [...] Read more.

The most modern technique utilized to create intricate manufactured parts for a variety of applications is called additive manufacturing (AM). Fused deposition modeling (FDM) has been acknowledged as the greatest consideration in the development and industrial sectors. The main objective of this study was to investigate how printing factors affected the mechanical characteristics of printed samples. Samples were produced via an FDM 3D printer in compliance with an ASTM D638 using a variety of input settings, including orientation, layer thickness, speed, and infill pattern. Tensile tests and morphological analysis using a scanning electron microscope (SEM) were done on the printed samples. The results of this study demonstrate that factors including layer thickness, printing speed, and orientation significantly affect the tensile strength of the ABS-printed samples. The 45° orientations, 0.3 mm thickness, and normal speed had a significant impact on the tensile strength of the ABS-printed samples. On the other hand, samples with a 90° orientation, 0.4 mm thickness, and fast speed show better elongation performance than other samples, according to Young’s modulus results. The SEM results for microscopic analysis show that samples S2 (loose infill, 45° orientation, 0.3 mm thickness, and normal speed), S5 (solid infill, 45° orientation, 0.3 mm thickness, and normal speed), and S8 (hollow infill, 45° orientation, 0.3 mm thickness, and normal speed) had a highly packed structure and robust. Discovering the parameter settings that could lead to greater mechanical and physical characteristics would undoubtedly assist designers and manufacturers worldwide as the FDM 3D printer becomes more and more crucial in manufacturing engineering parts. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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24 pages, 7122 KiB  

Open AccessArticle

A Low-Cost Microcontroller-Based Normal and Abnormal Conditions Classification Model for Induction Motors Using Self-Organizing Feature Maps (SOFM)

by Pedro Ponce, Brian Anthony, Aniruddha Suhas Deshpande and Arturo Molina

Energies 2023, 16(21), 7340; https://doi.org/10.3390/en16217340 - 30 Oct 2023

Viewed by 761

Abstract

Digital twins have provided valuable information for making effective decisions to ensure high efficiency in the manufacturing process using virtual models. Consequently, AC electric motors play a pivotal role in this framework, commonly employed as the primary electric actuators within Industry 4.0. In [...] Read more.

Digital twins have provided valuable information for making effective decisions to ensure high efficiency in the manufacturing process using virtual models. Consequently, AC electric motors play a pivotal role in this framework, commonly employed as the primary electric actuators within Industry 4.0. In addition, classification systems could be implemented to identify normal and abnormal operating conditions in electric machines. Moreover, the execution of such classification systems in low-cost digital embedded systems is crucial, enabling continuous monitoring of AC electric machines. Self-Organized Maps (SOMs) offer a promising solution for implementing classification systems in low-cost embedded systems due to their ability to reduce system dimensionality and visually represent the model’s features, so local digital systems can be used as classification systems. Therefore, this paper aims to investigate the utilization of SOMs for classifying operating conditions in AC electric machines. Furthermore, when integrated into an embedded system, SOMs detect abnormal conditions in AC electric machines. A trained SOM is deployed on a C2000 microcontroller to exemplify the proposed approach. It should be noted that the proposed structure can be adapted for implementation with different systems in the context of Industry 4.0. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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12 pages, 5426 KiB  

Open AccessArticle

Study of Wire-Cut Electro-Discharge Machining of Heat-Resistant Nickel Alloys

by Timur Rizovich Ablyaz, Evgeny Sergeevich Shlykov, Karim Ravilevich Muratov, Sarabjeet Singh Sidhu, Dmitry Mikhailovich and Khairulin Vadim Takhirovich

Materials 2023, 16(20), 6743; https://doi.org/10.3390/ma16206743 - 18 Oct 2023

Viewed by 711

Abstract

This paper presents an analysis and theoretical model for assessing the quality and accuracy of wire-cut electro-discharge machining (WEDM) of products made from novel heat-resistant nickel alloys such as CrNi56KVMTYB. It is observed that WEDM processing of Ni alloy led to high surface [...] Read more.

This paper presents an analysis and theoretical model for assessing the quality and accuracy of wire-cut electro-discharge machining (WEDM) of products made from novel heat-resistant nickel alloys such as CrNi56KVMTYB. It is observed that WEDM processing of Ni alloy led to high surface roughness for the thick specimens, and electrical parameters such as pulse duration for the selected range depict an insignificant role in the value of surface roughness. On the other hand, the cut width of the machined surface decreases as the pulse duration increases, while the cut width is elevated for thick workpieces. Secondary discharges developed in WEDM have negative effects that cause sludge adhering and deterioration in the quality and productivity of processing. The regression model is developed to predict the surface roughness and cut width of machined surfaces, which holds significant importance in modern engineering. The workpiece is examined for surface integrity and material deposition. It is observed that an increase in the height of the specimen leads to the occurrence of secondary discharges, which in turn results in the formation of cracks on the surfaces of high-temperature nickel alloys. These cracks have a detrimental effect on the performance of critical products made from next-generation heat-resistant nickel alloys. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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21 pages, 1719 KiB  

Open AccessArticle

The Green Value Engineering Methodology: A Sustainability-Driven Project Management Tool for Capital Projects in Process Industry

by Alessandro Rosengart, Maja Granzotto, Rudi Wierer, Gianluca Pazzaglia, Alessandro Salvi and Giovanni Dotelli

Sustainability 2023, 15(20), 14827; https://doi.org/10.3390/su152014827 - 12 Oct 2023

Viewed by 1572

Abstract

Process industry renovation is mostly driven by business objectives like productivity enhancement and cost reduction, which hinder the “shift towards a sustainable manufacturing” called by political and academic institutions. In this paper, the project management methodology of Value Engineering, used for cost reduction [...] Read more.

Process industry renovation is mostly driven by business objectives like productivity enhancement and cost reduction, which hinder the “shift towards a sustainable manufacturing” called by political and academic institutions. In this paper, the project management methodology of Value Engineering, used for cost reduction in large capital projects, is extended to improve not only economic figures, but also environmental sustainability indicators. The methods can guide project design to reduce the consumption of natural resources and the generation of waste, closing a gap between sustainability targets and production needs. Sustainability metrics derived from a simplified life cycle assessment approach are used to achieve quick but reliable estimates of the environmental impact reductions against a base scenario. The project governance is thus supported when assessing potential trade-offs between environmental and economic advantage, encouraging shared and de-risked decisions. Even though limited by the project boundaries of time and budget and by the simplified impact assessment approach, the method promotes a lean and incremental implementation of sustainable manufacturing practices, applicable also to routinary interventions. The methodology is illustrated through application examples from a real case study, an EUR 100 M chemical plant expansion project for a pharmaceutical company in Italy. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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14 pages, 3039 KiB  

Open AccessArticle

Continuous Extrusion Forming Technology of Magnesium Alloy Thin-Walled Tubules

by Xi Yang, Shihan Sun, Zheng Zhou, Xuewen Chen and Guoqing Chen

Materials 2023, 16(17), 5803; https://doi.org/10.3390/ma16175803 - 24 Aug 2023

Viewed by 857

Abstract

This paper proposes a new technology of superimposed billet extrusion-forming for thin-walled magnesium alloy tubes. This process represents an improvement over the current technology, which suffers from low production efficiency, poor forming accuracy, and low material utilization. We developed a detailed forming process [...] Read more.

This paper proposes a new technology of superimposed billet extrusion-forming for thin-walled magnesium alloy tubes. This process represents an improvement over the current technology, which suffers from low production efficiency, poor forming accuracy, and low material utilization. We developed a detailed forming process and mold structure, in which the excess material of the front billet is extruded out of the mold as the rear billet pushes on the front one. Through continuous extrusion, online direct water cooling, and cutting, the automated continuous production of thin-walled tubules is achieved. The optimization of the mandrel structure and its hovering action is also included, with the aim of improving the lifespan of the mandrel and the accuracy of tube size. The numerical simulation method evaluates the effect of the die angle (α) on the tube, formed using FORGE NXT 1.1. The results show that for an angle of less than 70°, the defect length of the tube decreases as the die angle decreases, forming an ordered flow of superimposed billets. If the angle is less than 50°, the two adjacently formed tubes separate automatically, with no need for the subsequent cutting process. The best choice of die angle is about 50°, which takes into account the effect of the change in extrusion force. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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20 pages, 1461 KiB  

Open AccessArticle

Integrating Absolute Sustainability and Social Sustainability in the Digital Product Passport to Promote Industry 5.0

by Luigi Panza, Giulia Bruno and Franco Lombardi

Sustainability 2023, 15(16), 12552; https://doi.org/10.3390/su151612552 - 18 Aug 2023

Cited by 3 | Viewed by 1954

Abstract

The establishment of the digital product passport is regarded to be a prominent tool to promote environmental and social sustainability, thus enabling the transition towards Industry 5.0. In this way, it represents a holistic tool for the decision-making process of several actors of [...] Read more.

The establishment of the digital product passport is regarded to be a prominent tool to promote environmental and social sustainability, thus enabling the transition towards Industry 5.0. In this way, it represents a holistic tool for the decision-making process of several actors of a product’s value chain. However, its development is still ongoing and the absolute perspective of environmental sustainability and the social sustainability have been overlooked. The present work aims to fill these gaps and complement the literature currently available on the digital product passport with a threefold purpose. Firstly, by referring to social life cycle assessment methodologies, useful social indicators to include in the digital product passport are discussed and proposed. Secondly, the need for an absolute perspective of environmental sustainability that respects the natural limits of our planet is presented; based on the LCA methodology and the Planetary Boundaries framework, environmental attributes and environmental impact indicators with the corresponding threshold are proposed to be included in the passport and enable the so-called absolute environmental sustainability assessment of products. Finally, a framework based on a cyber-physical system for filling in the digital product passport throughout a product lifecycle is conceived. This work represents an example of how the hallmark technologies of Industry 4.0 can be used towards Industry 5.0. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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22 pages, 1707 KiB  

Open AccessStudy Protocol

Analyzing the Factors for Implementing Make-to-Order Manufacturing System

by Surbhi Upadhyay, Suresh Kumar Garg and Rishu Sharma

Sustainability 2023, 15(13), 10312; https://doi.org/10.3390/su151310312 - 29 Jun 2023

Cited by 1 | Viewed by 1806

Abstract

Make-to-order (MTO) is becoming vital for meeting ever-changing customer requirements. Growing demand for customized items has been linked to a rise in the proportion of MTO businesses. Many sectors and product categories have implemented the MTO concept and achieved a competitive edge in [...] Read more.

Make-to-order (MTO) is becoming vital for meeting ever-changing customer requirements. Growing demand for customized items has been linked to a rise in the proportion of MTO businesses. Many sectors and product categories have implemented the MTO concept and achieved a competitive edge in sustainable manufacturing. However, in the case of the automobile sector, little work has been carried out, both in research and practice. In this study, our objective is to identify and prioritize the critical success factors (CSF) which can affect the implementation of make-to-order and rank the different strategies to implement MTO manufacturing systems for passenger cars. This paper proposes an integrated approach where an Analytic Hierarchy Process (AHP) is used for prioritizing factors and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is used for ranking the strategies for implementation. The study shows that a customer-centric strategy would be the best solution to implement MTO in the automobile sector. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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19 pages, 25599 KiB  

Open AccessArticle

Apparatus Design of One-Step Double-Side Friction Stir Welding for Aluminum Plates

by Nurul Muhayat, Ericha Dwi Wahyu Syah Putri, Hendrato, Yohanes Pringeten Dilianto Sembiring Depari, Poppy Puspitasari, Jamasri, Aditya Rio Prabowo and Triyono

Designs 2023, 7(3), 75; https://doi.org/10.3390/designs7030075 - 12 Jun 2023

Viewed by 1233

Abstract

Aluminum alloys emerged as one of the materials used in manufacturing automotive car bodies due to their advantageous properties such as high strength-to-weight ratio, relatively low cost, high ductility, and high corrosion resistance. However, joining aluminum alloys using fusion welding poses serious problems [...] Read more.

Aluminum alloys emerged as one of the materials used in manufacturing automotive car bodies due to their advantageous properties such as high strength-to-weight ratio, relatively low cost, high ductility, and high corrosion resistance. However, joining aluminum alloys using fusion welding poses serious problems due to the high solubility of hydrogen gas, which causes porosity in welding metal. Subsequently, solid-state welding, such as friction stir welding (FSW), has been considered a porosity-free aluminum joining method. However, the method has limitations, such as low flexibility and the need for a complex clamping system. It is particularly problematic when welding plates. It causes the welding process to be carried out twice on opposite sides, resulting in longer production times. This study designed and assembled a one-step double-side FSW apparatus to address this challenge and conducted welding trials with various welding parameters. During the welding trial, the upper and lower tool rotation varied at 900/900 rpm and 1500/1500 rpm. As a result, one-step double-side FSW was successfully used for welding 6 mm aluminum without any porosity defects. Faster tool rotation results in a wider heat-affected area and higher tensile strength. In addition, the hard test showed that the one-step double-side FSW process had a lower hardness compared to the hardness of the base metal. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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20 pages, 22189 KiB  

Open AccessArticle

Design of an Experimental Approach for Characterization and Performance Analysis of High-Frequency Transformer Core Materials

by Daniel van Niekerk, Brydon Schoombie and Pitshou Bokoro

Energies 2023, 16(9), 3950; https://doi.org/10.3390/en16093950 - 08 May 2023

Cited by 1 | Viewed by 1371

Abstract

High-frequency transformer core materials are used in power converter applications due to high efficiency performance. Their volume and weight can be reduced when higher operating frequencies are used but at the expense of an increase in core material losses. Some studies analyzed transformer [...] Read more.

High-frequency transformer core materials are used in power converter applications due to high efficiency performance. Their volume and weight can be reduced when higher operating frequencies are used but at the expense of an increase in core material losses. Some studies analyzed transformer core material performance by using finite element method (FEM) analysis, while others used an experimental model. This study proposes an experimental approach to compare the high-frequency transformer efficiency performance of different core material types. In this way, newly produced core material performance can be rapidly analyzed by comparing it against a known core material type, thereby resulting in the fast identification of improved core material design. This empirical approach makes use of a standard half-bridge inverter topology to enable an analysis of high-frequency transformer core material efficiency performance. Actual voltage and current measurements are used to determine the efficiency and output power performance throughout a specified constant current load range at different switching frequencies. Initially commercial standard polycrystalline or ferrite E-core materials were used to validate the characterization jig performance measured curve trends. The usefulness of the jig is then demonstrated by comparatively analyzing and then verifying the expected performance difference between polycrystalline and nanocrystalline toroidal core materials. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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24 pages, 11583 KiB  

Open AccessArticle

Effect of Low-Temperature Plasma Surface Treatment on Bonding Properties of Single-Lap Joint of Thermosetting Composites

by Liwei Wen, Xinying Xu and Lihua Qin

Polymers 2023, 15(7), 1631; https://doi.org/10.3390/polym15071631 - 24 Mar 2023

Cited by 4 | Viewed by 1758

Abstract

Bonding is one of the main forms of composite bonding. In order to investigate the effect of low-temperature plasma surface treatment on the bonding properties of carbon fiber-reinforced epoxy resin composites (CF/EP), a single-lap joint of CF/EP was prepared. The surface of the [...] Read more.

Bonding is one of the main forms of composite bonding. In order to investigate the effect of low-temperature plasma surface treatment on the bonding properties of carbon fiber-reinforced epoxy resin composites (CF/EP), a single-lap joint of CF/EP was prepared. The surface of the CF/EP was treated with atmospheric pressure “low-temperature plasma spray” equipment, and the tensile shear strength, surface morphology, surface contact angle and surface chemical composition of the CF/EP before and after plasma treatment were characterized. Finally, the samples were treated with traditional sandblasting, compared and analyzed. The results show that the effect of low-temperature plasma surface treatment on CF/EP joints is better than that of traditional sandblasting treatment. After low-temperature plasma surface treatment, the tensile shear strength of the CF/EP single-lap joint increased by 119.59% at most, and the failure form of the joint changed from untreated interface failure to mixed failure dominated by cohesion failure. Plasma can etch the surface of composite materials, the mechanical interlock between the carbon fiber and glue is enhanced and the bonding performance of the composite is improved. In addition, after low-temperature plasma surface treatment, the introduction of a large number of oxygen-containing active groups such as C-O and C=O can increase the surface free energy, reduce the contact angle and improve the surface activity and wettability of the composites. However, too long a treatment time will lead to excessive plasma etching of carbon fibers, thus weakening the active effect of the oxygen-containing active groups on the surface of the composites, and the surface wettability is no longer improved, but the adhesive properties of CF/EP are reduced. This paper plays a guiding role in the bonding technology of composite materials. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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15 pages, 7673 KiB  

Open AccessArticle

Multi-Stage Thermal Modelling of Extrusion-Based Polymer Additive Manufacturing

by Jiong Yang, Hexin Yue, Wajira Mirihanage and Paulo Bartolo

Polymers 2023, 15(4), 838; https://doi.org/10.3390/polym15040838 - 08 Feb 2023

Cited by 2 | Viewed by 1860

Abstract

Additive manufacturing is one the most promising fabrication strategies for the fabrication of bone tissue scaffolds using biodegradable semi-crystalline polymers. During the fabrication process, polymeric material in a molten state is deposited in a platform and starts to solidify while cooling down. The [...] Read more.

Additive manufacturing is one the most promising fabrication strategies for the fabrication of bone tissue scaffolds using biodegradable semi-crystalline polymers. During the fabrication process, polymeric material in a molten state is deposited in a platform and starts to solidify while cooling down. The build-up of consecutive layers reheats the previously deposited material, introducing a complex thermal cycle with impacts on the overall properties of printed scaffolds. Therefore, the accurate prediction of these thermal cycles is significantly important to properly design the additively manufactured polymer scaffolds and the bonding between the layers. This paper presents a novel multi-stage numerical model, integrating a 2D representation of the dynamic deposition process and a 3D thermal evolution model to simulate the fabrication process. Numerical simulations show how the deposition velocity controls the spatial dimensions of the individual deposition layers and the cooling process when consecutive layers are deposited during polymer printing. Moreover, numerical results show a good agreement with experimental results. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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13 pages, 5083 KiB  

Open AccessArticle

Laser-Assisted Robotic Roller Forming of Ultrahigh-Strength Steel QP1180 with High Precision

by Junying Min, Jincheng Wang, Junhe Lian, Yi Liu and Zeran Hou

Materials 2023, 16(3), 1026; https://doi.org/10.3390/ma16031026 - 23 Jan 2023

Cited by 6 | Viewed by 1853

Abstract

Laser-assisted forming provides a perfect solution that overcomes the formability of low-ductility materials. In this study, laser-assisted robotic roller forming (LRRF) was applied to bend ultrahigh-strength steel sheet (a quenching and partitioning steel with a strength grade of 1180 MPa), and the effects [...] Read more.

Laser-assisted forming provides a perfect solution that overcomes the formability of low-ductility materials. In this study, laser-assisted robotic roller forming (LRRF) was applied to bend ultrahigh-strength steel sheet (a quenching and partitioning steel with a strength grade of 1180 MPa), and the effects of laser power density on the bending forces, springback, and bending radius of the final parts were investigated. The results show that LRRF is capable of reducing bending forces by 43%, and a compact profile with high precision (i.e., a springback angle smaller than 1° and a radius-to-thickness ratio of ~1.2) was finally achieved at a laser power density of 10 J/mm². A higher forming temperature, at which a significant decrease in strength is observed, is responsible for the decrease of forming forces with a laser power density of higher than 7.5 J/mm²; another reason could be the heating-to-austenitization temperature and subsequent forming at a temperature above martensitic-transformation temperature. Forming takes place at a higher temperature with lower stresses, and unloading occurs at a relatively lower temperature with the recovery of Young’s modulus; both facilitate the reduction of springback angles. In addition, the sharp bending radius is considered to be attributed to localized deformation and large plastic strains at the heating area. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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14 pages, 6266 KiB  

Open AccessArticle

Manufacturing Constraints in Topology Optimization for the Direct Manufacturing of Extrusion-Based Additively Manufactured Parts

by Tobias Rosnitschek, Tobias Baumann, Christian Orgeldinger, Bettina Alber-Laukant and Stephan Tremmel

Designs 2023, 7(1), 8; https://doi.org/10.3390/designs7010008 - 05 Jan 2023

Viewed by 2372

Abstract

Additive manufacturing is a potentially disruptive technology with a high impact on supply chains and part design. While generally allowing much higher degrees of freedom in design than formative and subtractive manufacturing techniques, the necessity of support structures can diminish the impact of [...] Read more.

Additive manufacturing is a potentially disruptive technology with a high impact on supply chains and part design. While generally allowing much higher degrees of freedom in design than formative and subtractive manufacturing techniques, the necessity of support structures can diminish the impact of additive manufacturing. This article presents a methodology based on finite spheres to integrate knowledge about process limitations into topology optimization for the direct extrusion-based additive manufacturing of parts with maximized stiffness and strength and minimized support structures. This methodology has been included within our self-developed Freeware Z88 Arion^® V3. We investigated the impact of the manufacturing constraints on the additive manufacturing process regarding effective material usage on application test examples. The test results showed that the design proposals created while applying the finite spheres and two-step smoothing needed significantly less or no support material for all application examples. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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11 pages, 1263 KiB  

Open AccessArticle

High-Strength and Heat-Insulating Cellular Building Concrete Based on Calcined Gypsum

by Adrian Ioana, Lucian Paunescu, Nicolae Constantin, Valeriu Rucai, Cristian Dobrescu, Vili Pasare and Alexandra Istrate

Materials 2023, 16(1), 118; https://doi.org/10.3390/ma16010118 - 22 Dec 2022

Cited by 2 | Viewed by 1334

Abstract

A cellular concrete with a fine porous structure was experimentally made using the corrosion technique for aluminum powder as an expanding agent in an aqueous solution of Ca(OH)₂. The originality of this paper was the use of our own production method [...] Read more.

A cellular concrete with a fine porous structure was experimentally made using the corrosion technique for aluminum powder as an expanding agent in an aqueous solution of Ca(OH)₂. The originality of this paper was the use of our own production method for the fine aluminum powder through atomizing the recycled molten waste of this metal using concentrated jets of nitrogen. Additionally, the waste melting technique involved our own microwave heating method. A high weight proportion of calcined gypsum (maximum 82.3%) represented the main concrete binder. Using moderate contents of coal fly ash (3.6–11.1%) together with perlite (4.6–6.4%) to reduce the pore size and silica fume (0.3–1.2%) with pozzolanic properties, the aim was to obtain a macrostructure characterized by a very low pore size and to increase the compressive strength (by up to 4.1 MPa), despite the relatively low density (below 641 kg/m³). An industrial method of increasing the mechanical strength by steam curing fresh concrete was applied. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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26 pages, 9046 KiB  

Open AccessArticle

Optimisation of Selective Laser Melted Ti6Al4V Functionally Graded Lattice Structures Accounting for Structural Safety

by Lei Zhu, Xiaoyang Wang, Liao Sun, Quandong Hu and Nan Li

Materials 2022, 15(24), 9072; https://doi.org/10.3390/ma15249072 - 19 Dec 2022

Cited by 3 | Viewed by 1908

Abstract

This paper presents a new framework for lightweight optimisation of functionally graded lattice structures (FGLSs) with a particular focus on enhancing and guaranteeing structural safety through three main contributions. Firstly, a design strategy of adding fillets to the joints of body-centred cubic (BCC) [...] Read more.

This paper presents a new framework for lightweight optimisation of functionally graded lattice structures (FGLSs) with a particular focus on enhancing and guaranteeing structural safety through three main contributions. Firstly, a design strategy of adding fillets to the joints of body-centred cubic (BCC) type lattice cells was proposed to improve the effective yield stress of the lattices. Secondly, effective properties of lattice metamaterials were experimentally characterised by conducting quasi-static uniaxial compression tests on selective laser melted specimens of both Ti6Al4V BCC and filleted BCC (BCC-F) lattices with different relative densities. Thirdly, a yield stress constraint for optimising FGLSs was developed based on surrogate models quantifying the relationships between the relative density and the effective properties of BCC and BCC-F lattices developed using experimental results assisted by numerical homogenisation. This framework was tested with two case studies. Results showed that structural safety with respect to avoiding yield failure of the optimised FGLSs can be ensured and the introduction of fillets can effectively improve the strength-to-weight ratio of the optimised FGLSs composed of BCC type lattices. The BCC-F FGLS achieved 14.5% improvement in weight reduction compared with BCC FGLS for the Messerschmitt-Bölkow-Blohm beam optimisation case study. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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37 pages, 12619 KiB  

Open AccessReview

Energy Saving by Parametric Optimization and Advanced Lubri-Cooling Techniques in the Machining of Composites and Superalloys: A Systematic Review

by Rüstem Binali, Abhishek Dhananjay Patange, Mustafa Kuntoğlu, Tadeusz Mikolajczyk and Emin Salur

Energies 2022, 15(21), 8313; https://doi.org/10.3390/en15218313 - 07 Nov 2022

Cited by 8 | Viewed by 2223

Abstract

The resources of the earth are being consumed day by day with the increasing population and necessities of humankind in many areas, such as industrial applications and basic needs in houses, workplaces and transportation. As a consequence, careful usage of the energy sources [...] Read more.

The resources of the earth are being consumed day by day with the increasing population and necessities of humankind in many areas, such as industrial applications and basic needs in houses, workplaces and transportation. As a consequence, careful usage of the energy sources and the conversed energy is of great importance in order to obtain sustainable development. Machining operations have a large percentage of all manufacturing methods in terms of depleted energy which gives them a high potential for reducing the total energy consumption. The approaches handled in the literature for the minimization of the consumed energy in the machining industry were considered in this study. While several machinability characteristics under different machining processes were investigated broadly in the context of composites and superalloys, the comparison of these systems has been given cursory attention in the current literature, specifically for cutting energy saving. The overall performance of these group material systems utilizing widely in numerous significant industrial areas supplies important signs about manufacturing costs, service conditions and environmental impacts. It is highly crucial to monitor the indicators of energy-saving phenomena of the machined parts since the mechanisms behind the energy consumption of these systems is very complex and dynamic owing to different process-induced variables. This well-organized review paper distinguishes itself from previous studies in this field since the comprehensive literature survey paves the way for diverse approaches that regard energy saving, especially for composites and superalloys under different machining operations. This overview paper aims to contribute to the current literature by highlighting the effects of the state-of-the-art approaches in reducing energy consumption in the machining of industrially important materials. This study can also establish a framework in the context of the process-property interactions to comprehend the influence of energy-saving mechanisms through machining in a system of interest. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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49 pages, 16359 KiB  

Open AccessReview

Graphene Synthesis Techniques and Environmental Applications

by Qaisar Abbas, Pragati A. Shinde, Mohammad Ali Abdelkareem, Abdul Hai Alami, Mojtaba Mirzaeian, Arti Yadav and Abdul Ghani Olabi

Materials 2022, 15(21), 7804; https://doi.org/10.3390/ma15217804 - 04 Nov 2022

Cited by 21 | Viewed by 4032

Abstract

Graphene is fundamentally a two-dimensional material with extraordinary optical, thermal, mechanical, and electrical characteristics. It has a versatile surface chemistry and large surface area. It is a carbon nanomaterial, which comprises sp² hybridized carbon atoms placed in a hexagonal lattice with one-atom [...] Read more.

Graphene is fundamentally a two-dimensional material with extraordinary optical, thermal, mechanical, and electrical characteristics. It has a versatile surface chemistry and large surface area. It is a carbon nanomaterial, which comprises sp² hybridized carbon atoms placed in a hexagonal lattice with one-atom thickness, giving it a two-dimensional structure. A large number of synthesis techniques including epitaxial growth, liquid phase exfoliation, electrochemical exfoliation, mechanical exfoliation, and chemical vapor deposition are used for the synthesis of graphene. Graphene prepared using different techniques can have a number of benefits and deficiencies depending on its application. This study provides a summary of graphene preparation techniques and critically assesses the use of graphene, its derivates, and composites in environmental applications. These applications include the use of graphene as membrane material for the detoxication and purification of water, active material for gas sensing, heavy metal ions detection, and CO₂ conversion. Furthermore, a trend analysis of both synthesis techniques and environmental applications of graphene has been performed by extracting and analyzing Scopus data from the past ten years. Finally, conclusions and outlook are provided to address the residual challenges related to the synthesis of the material and its use for environmental applications. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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8 pages, 1884 KiB  

Open AccessCommunication

Impact of NaOH on the Hydrothermal Oxidation of Guaiacol for the Production of Value-Added Products

by Xu Zeng, Guodong Yin, Yangyuan Zhou and Jianfu Zhao

Energies 2022, 15(21), 8039; https://doi.org/10.3390/en15218039 - 28 Oct 2022

Cited by 1 | Viewed by 1137

Abstract

In this study, the impact of NaOH on the hydrothermal oxidation of guaiacol was investigated. It was found that NaOH significantly accelerated the production of formic acid and acetic acid with H₂O₂ or CuO as the oxidant. With the strong [...] Read more.

In this study, the impact of NaOH on the hydrothermal oxidation of guaiacol was investigated. It was found that NaOH significantly accelerated the production of formic acid and acetic acid with H₂O₂ or CuO as the oxidant. With the strong oxidant, H₂O₂, the highest acetic acid yield (15.73%) and formic acid (5.64%) were obtained at 300 °C for 90 s with NaOH 1.0 mol·L⁻¹ and a 100% H₂O₂ oxygen supply. In comparison, with CuO as the oxidant, the highest values of acetic acid (13.42%) and formic acid (4.21%) were acquired at 250 °C for 6 h with NaOH 1.0 mol·L⁻¹. Formic acid and acetic acid were generated through the oxidation of intermediates, such as levulinic acid, fumaric acid, maleic acid, etc. These results demonstrated that NaOH catalytic hydrothermal oxidation has potential for the production of value-added chemicals from biomass materials. When CuO is used as the oxidant, this process could also be used as a green method for copper smelting along with the utilization of lignin biomass. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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56 pages, 18190 KiB  

Open AccessReview

The Design and Optimization of Natural Gas Liquefaction Processes: A Review

by Lei Gao, Jiaxin Wang, Maxime Binama, Qian Li and Weihua Cai

Energies 2022, 15(21), 7895; https://doi.org/10.3390/en15217895 - 24 Oct 2022

Cited by 5 | Viewed by 6847

Abstract

As the energy crisis intensifies, the global demand for natural gas is growing rapidly. Liquefied natural gas (LNG) technology is among the delivery solutions with flexible and reliable application prospects and is already a significant field of research in energy utilization. The performance [...] Read more.

As the energy crisis intensifies, the global demand for natural gas is growing rapidly. Liquefied natural gas (LNG) technology is among the delivery solutions with flexible and reliable application prospects and is already a significant field of research in energy utilization. The performance of natural gas liquefaction process has a major influence on the production capacity, energy consumption, economics, and safety of the entire supply chain. Many scholars have conducted numerous studies on various LNG processes and designed many classical processes. This paper summarizes and discusses current research status and development level in the design and optimization of natural gas liquefaction processes in recent years, mainly focusing on cascade liquefaction process, expansion liquefaction process, and mixed refrigerant liquefaction process. The advantages and disadvantages of various liquefaction processes are compared and analyzed in terms of liquefaction capacity, energy consumption, economy, safety, and adaptability. In addition, the rapid development of pressurized liquefaction technology in recent years and its application outlooks are also introduced in detail. Finally, the present situation and industrial demand of LNG process are analyzed, and reasonable suggestions and future research prospects are put forward. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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13 pages, 4935 KiB  

Open AccessArticle

Fracture Strain of Al–Si-Coated Press-Hardened Steels under Plane-Strain Bending

by Zeran Hou, Wei Song, Hongliang Yi, Jianfeng Wang and Junying Min

Materials 2022, 15(20), 7345; https://doi.org/10.3390/ma15207345 - 20 Oct 2022

Cited by 3 | Viewed by 1574

Abstract

Press-hardened steel (PHS) is widely applied to fabricate vehicle body structures for attaining mass reduction and fuel economy without sacrificing occupant safety. The VDA bendability test is often used to characterize the fracture resistance of PHS under plane-strain bending conditions. As lightweighting continues [...] Read more.

Press-hardened steel (PHS) is widely applied to fabricate vehicle body structures for attaining mass reduction and fuel economy without sacrificing occupant safety. The VDA bendability test is often used to characterize the fracture resistance of PHS under plane-strain bending conditions. As lightweighting continues to be a design imperative in the automotive industry, it is desirable to develop and adopt more press-hardened components with higher fracture resistance. In this work, four Al–Si-coated 22MnB5 steels with various initial thicknesses and coating weights were studied. A newly developed methodology was used to calculate the fracture limit strain under plane-strain bending. The results indicate that although the four investigated 22MnB5 steels exhibit similar tensile properties under uniaxial tension, their bending performance per the VDA 238-100 standard differs significantly. The PHS with a low coating weight possesses a higher bending angle and, hence, a larger fracture limit strain. Meanwhile, the peak bending force can be 10% higher than the PHS with a standard coating weight at the same sheet thickness. Therefore, it is expected that PHS with higher fracture strain will have the potential for lightweighting due to its enhanced resistance to fracture and higher energy absorption capability. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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14 pages, 17047 KiB  

Open AccessArticle

Reveal the Viscoplastic Behaviour and Microstructure Evolution of Stainless Steel 316L

by Qiong Lu, Chi Zhang, Wei Wang, Shuai Jiang, Lee Aucott, Tabassam Yasmeen and Jun Jiang

Materials 2022, 15(20), 7064; https://doi.org/10.3390/ma15207064 - 11 Oct 2022

Cited by 2 | Viewed by 1266

Abstract

Stainless steel 316L is a widely used structural material in the nuclear industry because of its excellent corrosion resistance and mechanical properties. However, very little research can be found on its viscoplastic behaviour and microstructure evolution at warm and hot deformation conditions, which [...] Read more.

Stainless steel 316L is a widely used structural material in the nuclear industry because of its excellent corrosion resistance and mechanical properties. However, very little research can be found on its viscoplastic behaviour and microstructure evolution at warm and hot deformation conditions, which hinder the possible application of advanced manufacturing technologies for producing complex parts, such as superplastic forming or hydroforming. The aims of this study are to explore stainless steel 316L’s viscoplastic behaviour, to determine its strain rate sensitivities, and to reveal its underlying microstructure evolution; this will allow appropriate manufacturing (forming) technologies and the optimal forming condition to be determined. Hence, isothermal tensile tests at 700 °C, 800 °C, 900 °C, and 1000 °C at strain rates of 0.01 s⁻¹ and 0.001 s⁻¹ have been conducted. Moreover, the corresponding microstructure evolution, including the grain orientation and geometrically necessary dislocation density, has been revealed by the electron backscatter diffraction method. The data show the viscoplastic behaviour of stainless steel 316L under various thermomechanical deformation conditions and how microstructure evolution influences the viscoplastic flow stress. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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17 pages, 8549 KiB  

Open AccessArticle

Optimisation on the Performance of Bubble-Bursting Atomisation for Minimum Quantity Lubrication with Vegetable Oil Using Computational Fluid Dynamics Simulation

by Pin Han Yap, Jaharah A. Ghani and Wan Mohd. Faizal Wan Mahmood

Materials 2022, 15(12), 4355; https://doi.org/10.3390/ma15124355 - 20 Jun 2022

Cited by 1 | Viewed by 1258

Abstract

Sustainable and green machining technologies have become a welcomed topic in the manufacturing industries. One of the emerging sustainable technologies is minimum quantity lubrication (MQL). In this study, the optimisation and study of the bubble-bursting atomisation system applied to MQL machining is carried [...] Read more.

Sustainable and green machining technologies have become a welcomed topic in the manufacturing industries. One of the emerging sustainable technologies is minimum quantity lubrication (MQL). In this study, the optimisation and study of the bubble-bursting atomisation system applied to MQL machining is carried out through the computational fluid dynamics (CFD) simulation approach. Vegetable oil is selected as the cooling lubricant in this study. The performance of the bubble-bursting atomisation system is improved by alternating air inlet velocity and the gap distance between the inlets of bubble production. A velocity of 0.1 ms⁻¹ is suitable for the air at the inlets for the bubble production, whereas 10 ms⁻¹ is suitable for the velocity of the air at the inlet, where the droplets of vegetable oil are guided to the nozzle. Besides that, a 50 mm gap distance between the air inlets for the production of bubbles is able to avoid the occurrence of bubble coalescence. Under these conditions, optimal bubble sizes of 2–3 mm can be achieved, with a higher probability of nano-sized droplets being present in these ranges. Furthermore, a higher rate and smaller size of vegetable oil droplets escaping the atomisation chamber and reaching the machining zone will be generated. Thus, the performance of the MQL machining can be improved. Full article

(This article belongs to the Topic Efficient Manufacturing: Materials, Processes, and Systems)

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