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J. Manuf. Mater. Process., Volume 6, Issue 3 (June 2022) – 18 articles

Cover Story (view full-size image): The great interest of the transport industry in high-strength aluminium alloys and the advanced technology to locally improve the material formability has led to this research. In fact, this work investigated, by means of physical and numerical simulation, the effects of laser surface treatment on the softening and the fracture strain of the EN AW 6082 T6 alloy 1 mm thick. Compared to the state of the art, the novelty of this work is the use of the Gleeble 3180 physical simulator for reproducing, at lab scale and on small samples, laser thermal cycles, without exploiting a laser source. Results in agreement with the existing literature are obtained, reducing cost and material waste thanks to the physical simulation technique. View this paper
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Article
Carbonated 3D-Printable Polymer Composite for Thermo-Mechanically Stable Applications
J. Manuf. Mater. Process. 2022, 6(3), 66; https://doi.org/10.3390/jmmp6030066 - 15 Jun 2022
Cited by 2 | Viewed by 2091
Abstract
In this report, we investigate the infusion of carbon dioxide into a 3D-printable photosensitive polymer. The result is a carbonated polymer composite material. In use, polymer composite materials expect to succeed where ordinary polymers and metals fail. This is due to the tailorability [...] Read more.
In this report, we investigate the infusion of carbon dioxide into a 3D-printable photosensitive polymer. The result is a carbonated polymer composite material. In use, polymer composite materials expect to succeed where ordinary polymers and metals fail. This is due to the tailorability of composite materials for specific applications. Usually, micro/nano-particulates are embedded as fillers within a polymer matrix, enhancing the overall material properties. Here, carbon dioxide (CO2) microbubbles serve as the filler within a nylon-like polymer matrix. Additive manufacturing by stereolithography (SLA) of the carbonated polymer composite proved possible using the digital light projection (DLP) 3D printing technique. Post-heat treatment using thermogravimetric analysis of the samples at elevated temperatures resulted in a 33% mass reduction, indicative of nearly complete solvent removal and curing. An initial increase in polymer carbonation duration showed a 16% increase in porosity, more stable thermal profiles, and a 40% decrease in specific heat capacity. Thermo-mechanical compressive tests on an optimal carbonated sample revealed a 70% increase in compressive strength over its neat counterpart and a peak modulus at 50 °C of 60 MPa. Such 3D-printable carbonated polymer composites may find use in applications requiring high strength-to-weight ratio thermally stable polymers and applications requiring a versatile and convenient storage medium for on-demand CO2 deposition or supercritical fluid phase transformation. Full article
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Review
Additive Manufacturing: An Opportunity for the Fabrication of Near-Net-Shape NiTi Implants
J. Manuf. Mater. Process. 2022, 6(3), 65; https://doi.org/10.3390/jmmp6030065 - 14 Jun 2022
Cited by 24 | Viewed by 3099
Abstract
Nickel–titanium (NiTi) is a shape-memory alloy, a type of material whose name is derived from its ability to recover its original shape upon heating to a certain temperature. NiTi falls under the umbrella of metallic materials, offering high superelasticity, acceptable corrosion resistance, a [...] Read more.
Nickel–titanium (NiTi) is a shape-memory alloy, a type of material whose name is derived from its ability to recover its original shape upon heating to a certain temperature. NiTi falls under the umbrella of metallic materials, offering high superelasticity, acceptable corrosion resistance, a relatively low elastic modulus, and desirable biocompatibility. There are several challenges regarding the processing and machinability of NiTi, originating from its high ductility and reactivity. Additive manufacturing (AM), commonly known as 3D printing, is a promising candidate for solving problems in the fabrication of near-net-shape NiTi biomaterials with controlled porosity. Powder-bed fusion and directed energy deposition are AM approaches employed to produce synthetic NiTi implants. A short summary of the principles and the pros and cons of these approaches is provided. The influence of the operating parameters, which can change the microstructural features, including the porosity content and orientation of the crystals, on the mechanical properties is addressed. Surface-modification techniques are recommended for suppressing the Ni ion leaching from the surface of AM-fabricated NiTi, which is a technical challenge faced by the long-term in vivo application of NiTi. Full article
(This article belongs to the Special Issue Frontiers in Digital Manufacturing)
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Article
Physical Simulation of Laser Surface Treatment to Study Softening Effect on Age-Hardened Aluminium Alloys
J. Manuf. Mater. Process. 2022, 6(3), 64; https://doi.org/10.3390/jmmp6030064 - 10 Jun 2022
Cited by 2 | Viewed by 2031
Abstract
The automotive industry is interested in manufacturing components with tailored mechanical properties. To this end, advanced heating treatments can be exploited to obtain the so-called Tailored Heat-Treated Blanks (THTB). However, mechanical properties are strongly affected by the process parameters of heating treatments, which [...] Read more.
The automotive industry is interested in manufacturing components with tailored mechanical properties. To this end, advanced heating treatments can be exploited to obtain the so-called Tailored Heat-Treated Blanks (THTB). However, mechanical properties are strongly affected by the process parameters of heating treatments, which require a preliminary design. Physical simulation can be a decisive tool in this phase to obtain useful information at the laboratory scale, even when heat treatments such as those carried out with laser technologies impose high heating and cooling rates on the material. This work uses physical simulation to investigate the changes in strength and ductility caused by laser heat treatment (LHT) on aluminum alloys hardened by aging; the methodology was implemented on the EN AW 6082 T6 alloy. First, a finite-element (FE) transient thermal model was developed to simulate LHT by varying the process parameters (laser power/peak temperature and treatment speed). Second, the resulting thermal cycles were physically simulated by means of the Gleeble 3180 system. Third, the strength and the ductility of physically simulated specimens were evaluated through micro-hardness and tensile tests; to study aging effects, investigations were performed both (i) right after Gleeble tests (samples in the supersaturated solid state, i.e., as-physically simulated (APS) state) and (ii) after one week from Gleeble tests (aged specimens—T4 state). The obtained results show that there are peak temperatures that guarantee maximum softening levels for each investigated state (T4 and APS). The optimal peak temperature ranges are in agreement with the data in the literature, demonstrating that the proposed methodology is suitable for the study of softening phenomena on aging-hardened aluminum alloys. Full article
(This article belongs to the Special Issue Advances in Material Forming)
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Article
A Combination of Alloy Modification and Heat Treatment Strategies toward Enhancing the Properties of LPBF Processed Hot Working Tool Steels (HWTS)
J. Manuf. Mater. Process. 2022, 6(3), 63; https://doi.org/10.3390/jmmp6030063 - 10 Jun 2022
Cited by 2 | Viewed by 1785
Abstract
Hot working tool steels (HWTS) are popular for industrial applications such as injection molding tools, and casting dies because of their high wear resistance, fatigue, strength, and toughness properties, even at elevated temperatures. Conventionally, they go through multi-stage heat treatments in order to [...] Read more.
Hot working tool steels (HWTS) are popular for industrial applications such as injection molding tools, and casting dies because of their high wear resistance, fatigue, strength, and toughness properties, even at elevated temperatures. Conventionally, they go through multi-stage heat treatments in order to attain targeted microstructures. Achieving such microstructures with a laser powder bed fusion (LPBF) process will require tailor-made process parameters since it is characterized by non-equilibrium conditions, non-uniform temperature distribution, and metastable phase formation. Recent advances in the LPBF qualification of 1.2343/4 HWTS have shown commendable results but are still fraught with the limitations of poor ductility or extra post-heat treatment steps. For the industrial competitiveness of LPBF HWTS, the enhancement of strength and ductility and elimination of post processing is critical. Therefore, minimizing retained austenite in the as-built samples through pre-heat treatment or alloying to reduce post heat treatments without sacrificing strength will be economically important for industry. In this work, 1.2343 HWTS and its modified form were LPBF printed both in the as-built, pre- and post-heat-treated conditions. The results are discussed based on the correlations of the powder properties with LPBF—part density, microstructure, and mechanical properties. Full article
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Article
Tooling and Infusion Design Strategies to Reduce Trade-Offs in Forming and Infusion Quality of Multi-Textile CFRPs
J. Manuf. Mater. Process. 2022, 6(3), 62; https://doi.org/10.3390/jmmp6030062 - 09 Jun 2022
Viewed by 1407
Abstract
Achieving right-first-time-manufacture (RFTM) of co-infused textile assemblies is challenging, without improving the accessibility to design knowledge of trade-offs between different tooling and infusion strategies. As demonstrated in previous work, the choice between a flexible or rigid mould material can result in trade-offs between [...] Read more.
Achieving right-first-time-manufacture (RFTM) of co-infused textile assemblies is challenging, without improving the accessibility to design knowledge of trade-offs between different tooling and infusion strategies. As demonstrated in previous work, the choice between a flexible or rigid mould material can result in trade-offs between dimensional accuracy and geometrical precision. Similarly, the choice of an infusion strategy can result in trade-offs in infusion quality and time. Building on past work, an investigation into forming variability across the length of six co-infused multi-textile components, with three different tooling inserts and two infusions set-ups, was conducted. To quantitatively assess variation, a method adapting principles of statistical process control was employed to analyse the yarn crimp measured from high-resolution cross-sectional scans of the components. The results were compared to a geometrical and dimensional analysis of the manufactured parts presented in a previous work. The analysis represents a method for capturing forming differences in textile preforms, which can be used to inform designs for the manufacture of textile CFRPs. The results were used to improve a hybrid rigid-flexible tooling design for an infused multi-textile component. Full article
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Article
On the Accurate Prediction of Residual Stress in a Three-Pass Slot Nickel-Base Repair Weld by Numerical Simulations
J. Manuf. Mater. Process. 2022, 6(3), 61; https://doi.org/10.3390/jmmp6030061 - 01 Jun 2022
Cited by 1 | Viewed by 2059
Abstract
The activities within a European network to develop accurate experimental and numerical methods to assess residual stresses in structural weldments are reported. The NeT Task Group 6 or NeT-TG6 project examined an Alloy 600 plate containing a three-pass slot weld made with Alloy [...] Read more.
The activities within a European network to develop accurate experimental and numerical methods to assess residual stresses in structural weldments are reported. The NeT Task Group 6 or NeT-TG6 project examined an Alloy 600 plate containing a three-pass slot weld made with Alloy 82 consumables. A number of identical specimens were fabricated and detailed records of the manufacturing history were kept. Parallel measurement and simulation round robins were performed. Residual stresses were measured using neutron diffraction via five different instruments. The acquired database is large enough to generate reliable mean profiles, to identify clear outliers, and to establish the systematic uncertainty associated with this non-destructive technique. NeT-TG6 gives a valuable insight into the real-world variability of diffraction-based residual stress measurements, and forms a reliable foundation against which to benchmark other measurement methods. The mean measured profiles were used to validate the accuracy achieved by the network in the prediction of residual stresses. Full article
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Article
Powder Metallurgical Processing of Sn-Reinforced Al-Cu-Fe Quasicrystals: Structure, Microstructure and Toughening Behavior
J. Manuf. Mater. Process. 2022, 6(3), 60; https://doi.org/10.3390/jmmp6030060 - 31 May 2022
Cited by 9 | Viewed by 1991
Abstract
The present work deals with powder metallurgical processing of Sn-reinforced Al-Cu-Fe icosahedral quasicrystalline (IQC) composites processed through mechanical milling (MM) followed by hot pressing and pressureless sintering. The structure, microstructure and toughening behavior of the nanocomposite powders and bulk samples were investigated through [...] Read more.
The present work deals with powder metallurgical processing of Sn-reinforced Al-Cu-Fe icosahedral quasicrystalline (IQC) composites processed through mechanical milling (MM) followed by hot pressing and pressureless sintering. The structure, microstructure and toughening behavior of the nanocomposite powders and bulk samples were investigated through X-ray diffraction (XRD), optical metallography (OM), scanning electron microscopy (SEM) and indentation techniques. The XRD pattern suggested the coexistence of IQC and λ-Al13Fe4 (mC102; a = 1.549 nm, b = 0.808 nm, c = 1.248 nm) and B2-type Al (Cu, Fe) (cP2; a = 0.29 nm) crystalline phases in milled as well as sintered samples. The face-centered icosahedral (FCI) ordering was persistent even after 40 h of milling and sintering. The structural transformation during MM influences the indentation behavior of IQC-Sn nanocomposite powders, and the microhardness was found to be in the range of ~5.3 to 7.3 GPa. Further, efforts were made to study the indentation behavior of IQC-Sn composite prepared by pressureless sintering and hot pressing. The fracture toughness of the IQC-10Sn hot-pressed sample was found to be ~1.92 MPa.m, which is ~22% higher than that of the as-cast and annealed IQC. The enhancement in the fracture toughness resulted mainly from the inhibition of cracks by Sn reinforcement particles. This suggests that powder metallurgical processing can produce the IQC-Sn composite with an optimal combination of microhardness and fracture toughness. Full article
(This article belongs to the Special Issue Powder Metallurgy and Additive Manufacturing/3D Printing of Materials)
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Article
Assembly Line Overall Equipment Effectiveness (OEE) Prediction from Human Estimation to Supervised Machine Learning
J. Manuf. Mater. Process. 2022, 6(3), 59; https://doi.org/10.3390/jmmp6030059 - 27 May 2022
Cited by 3 | Viewed by 3337
Abstract
Nowadays, in the domain of production logistics, one of the most complex planning processes is the accurate forecasting of production and assembly efficiency. In industrial companies, Overall Equipment Effectiveness (OEE) is one of the most common used efficiency measures at semi-automatic assembly lines. [...] Read more.
Nowadays, in the domain of production logistics, one of the most complex planning processes is the accurate forecasting of production and assembly efficiency. In industrial companies, Overall Equipment Effectiveness (OEE) is one of the most common used efficiency measures at semi-automatic assembly lines. Proper estimation supports the right use of resources and more accurate and cost-effective delivery to the customers. This paper presents the prediction of OEE by comparing human prediction with one of the techniques of supervised machine learning through a real-life example. In addition to descriptive statistics, takt time-based decision trees are applied and the target-oriented OEE prediction model is presented. This concept takes into account recent data and assembly line targets with different weights. Using the model, the value of OEE can be predicted with an accuracy of within 1% on a weekly basis, four weeks in advance. Full article
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Article
Modelling and Optimization of Machining of Ti-6Al-4V Titanium Alloy Using Machine Learning and Design of Experiments Methods
J. Manuf. Mater. Process. 2022, 6(3), 58; https://doi.org/10.3390/jmmp6030058 - 27 May 2022
Cited by 9 | Viewed by 2395
Abstract
Ti-6Al-4V titanium is considered a difficult-to-cut material used in critical applications in the aerospace industry requiring high reliability levels. An appropriate selection of cutting conditions can improve the machinability of this alloy and the surface integrity of the machined surface, including the generation [...] Read more.
Ti-6Al-4V titanium is considered a difficult-to-cut material used in critical applications in the aerospace industry requiring high reliability levels. An appropriate selection of cutting conditions can improve the machinability of this alloy and the surface integrity of the machined surface, including the generation of compressive residual stresses. In this paper, orthogonal cutting tests of Ti-6Al-4V titanium were performed using coated and uncoated tungsten carbide tools. Suitable design of experiments (DOE) was used to investigate the influence of the cutting conditions (cutting speed Vc, uncut chip thickness h, tool rake angle γn, and the cutting edge radius rn) on the forces, chip compression ratio, and residual stresses. Due to the time consumed and the high cost of the residual stress measurements, they were only measured for selected cutting conditions of the DOE. Then, the machine learning method based on mathematical regression analysis was applied to predict the residual stresses for other cutting conditions of the DOE. Finally, the optimal cutting conditions that minimize the machining outcomes were determined. The results showed that when increasing the compressive residual stresses at the machined surface by 40%, the rake angle should be increased from negative (−6°) to positive (5°), the cutting edge radius should be doubled (from 16 µm to 30 µm), and the cutting speed should be reduced by 67% (from 60 to 20 m/min). Full article
(This article belongs to the Special Issue Advances in Modelling of Machining Operations)
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Article
Investigating the Influence of Material Extrusion Rates and Line Widths on FFF-Printed Graphene-Enhanced PLA
J. Manuf. Mater. Process. 2022, 6(3), 57; https://doi.org/10.3390/jmmp6030057 - 24 May 2022
Cited by 4 | Viewed by 2567
Abstract
Fused filament fabrication (FFF) is a widely used additive manufacturing process that can produce parts from thermoplastics. Its ease of operation and wide variety of materials make it a popular choice for manufacturing. To leverage such benefits, the commonly used thermoplastics (e.g., PLA [...] Read more.
Fused filament fabrication (FFF) is a widely used additive manufacturing process that can produce parts from thermoplastics. Its ease of operation and wide variety of materials make it a popular choice for manufacturing. To leverage such benefits, the commonly used thermoplastics (e.g., PLA and ABS) are impregnated with nanoparticles, short or continuous fibers, and other additives. The addition of graphene nanoplatelets to PLA makes for a high-quality filament possessing enhanced mechanical, electrical, and thermal properties. Even with the advancement in materials, the optimisation of the process parameter remains the most complex aspect for FFF. Therefore, this study investigates the influence of two under-researched and overlooked processing parameters (material extrusion rates and line widths) on commercially available graphene-enhanced PLA (GPLA). Nine different material extrusion rates (70% to 150%) and five different line widths (0.2 mm to 1 mm) were used to manufacture GPLA specimens using a low-cost, desktop-based 3D printer, as per British and international standards. The study analyses the influence of these two processing parameters on mass, dimensional accuracy, surface texture, and mechanical properties of GPLA specimens. A non-destructive test has also been conducted and correlated with three-point flexural test to establish its applicability in evaluating flexural properties of GPLA. The results how that small line widths provide more accuracy with longer print times whereas large line widths offer more strength with shorter printing times. Increase in material extrusion rates adversely affect the surface finish and hardness but positively influence the flexural strength of GPLA specimens. The study shows that the manipulation of material extrusion rates and line widths can help designers in understanding the limitations of the default printing settings (100% material extrusion rate and 0.4 mm line width) on most desktop 3D printers and identifying the optimal combination to achieve desired properties using the FFF process. Full article
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Article
Comparative Analysis of the Solid Conveying of Regrind, Virgin and Powdery Polyolefins in Single-Screw Extrusion
J. Manuf. Mater. Process. 2022, 6(3), 56; https://doi.org/10.3390/jmmp6030056 - 24 May 2022
Cited by 1 | Viewed by 2169
Abstract
The shape and size of processed materials play a crucial role in the solid conveying characteristics of single-screw extruders. Thus, the increasing amount of plastic regrind leads to new challenges in screw extrusion. This work investigates the conveying behavior of three distinctly different [...] Read more.
The shape and size of processed materials play a crucial role in the solid conveying characteristics of single-screw extruders. Thus, the increasing amount of plastic regrind leads to new challenges in screw extrusion. This work investigates the conveying behavior of three distinctly different material shapes in an axially as well as a helically grooved solid conveying zone. A uniform virgin polypropylene (PP) granule, an irregularly plate-shaped PP regrind and a powdery polyethylene (PE) are processed at screw speeds up to 1350 rpm. Thereby, frictionally engaged conveying in the grooves is visualized for the utilized powder. Similarly, the virgin granule is subject to forced conveying by interlocking in the grooves. The experimentally determined throughput is furthermore compared to analytical calculations which assume a so-called nut–screw conveying. It is found that these calculations perfectly predict the throughput when processing the virgin granule and the powder in a helically grooved barrel. In contrast, the analytical calculation significantly underestimates the throughput for the regrind. This underestimation is expected to be mainly caused by its plate shape and a difference in bulk density. The actual bulk density in the extruder is probably significantly higher due to both orientation and compaction effects compared to the measured bulk density that is used for the analytical calculation. Additionally, the regrind exhibits a fluctuating throughput due to the non-constant bulk density, which results from an irregular regrind shape and a broad size distribution. Full article
(This article belongs to the Special Issue Manufacturing and Processing of Recycled Plastics)
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Review
Insight into the Expected Impact of Sustainable Development in the Context of Industry 4.0: A Documentary Analysis Approach Based on Multiple Case Studies across the World
J. Manuf. Mater. Process. 2022, 6(3), 55; https://doi.org/10.3390/jmmp6030055 - 20 May 2022
Viewed by 2922
Abstract
Although industry 4.0 has gained increased attention in the industry, academic, and governmental fields, there is a lack of information about the relationship between this digital transformation and sustainable development. This work explores the concept of sustainability applied in industry 4.0 and the [...] Read more.
Although industry 4.0 has gained increased attention in the industry, academic, and governmental fields, there is a lack of information about the relationship between this digital transformation and sustainable development. This work explores the concept of sustainability applied in industry 4.0 and the main advantages that this revolution incorporates into society. To this end, a conscientiously documented investigation was conducted by reviewing actual case studies or scenarios where sustainability was applied in different manufacturing industries, enterprises, or research fields worldwide. A critical and descriptive analysis of the information was performed to identify the main tools and procedures that can be implemented in the industry to address the triple bottom line perspective of industry 4.0, and the results are presented in this document. From the analysis, it was observed that currently, I4.0 has been mainly adopted to improve efficiency and cost reduction in manufacturing companies. However, since only a few enterprises embrace the social paradigm of I4.0, a significant gap in understanding and unbalance is visualized. Therefore, we conclude that there is a lack of information on social benefits and the barriers that must be overcome from the social perspective. On the other hand, this work highlights the importance of adopting industry 4.0 as a positive way to improve the performance of emerging technologies, such as fuel cells, solar cells, and wind turbines, while producing products or services with high efficiency and profitability incomes. For practitioners, this work can provide insightful information about the real implications of I4.0 from a sustainability perspective in our daily life and the possible strategies to improve sustainable development. Full article
(This article belongs to the Special Issue Industry 4.0: Manufacturing and Materials Processing)
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Article
Additive Surface Graining in Prototype Tooling for Injection Molding
J. Manuf. Mater. Process. 2022, 6(3), 54; https://doi.org/10.3390/jmmp6030054 - 05 May 2022
Cited by 2 | Viewed by 2340
Abstract
Surface properties of injection molded parts have a strong effect on the visual and haptic perception of the parts by customers. Especially for injection molded automotive interior parts, grained surfaces can often be found. In conventional tooling, graining requires separate process steps. This [...] Read more.
Surface properties of injection molded parts have a strong effect on the visual and haptic perception of the parts by customers. Especially for injection molded automotive interior parts, grained surfaces can often be found. In conventional tooling, graining requires separate process steps. This makes the realization of grained injection molded prototype parts very complex. By additive manufacturing of injection molds in prototype tooling, it is possible to print micro structures into the mold surface in one printing operation. An injection mold with four different graining structures varying in depth and distance was designed and additively manufactured. The specification regarding the surface graining was analyzed by means of roughness measurements of the CAD model, injection mold and injection molded parts. Results show the feasibility of highly controllable additive surface graining. Full article
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Article
Influence of the Reaction Injection Moulding Process on the Thermomechanical Behaviour of Fast Curing Polyurethane
J. Manuf. Mater. Process. 2022, 6(3), 53; https://doi.org/10.3390/jmmp6030053 - 03 May 2022
Cited by 2 | Viewed by 2060
Abstract
In this contribution, the influence of the reaction injection moulding process on the thermomechanical material behaviour of aliphatic hexamethylene diisocyanate (HDI) based fast curing polyurethane is demonstrated. Uniaxial tensile tests, temperature-frequency dependent dynamic mechanical thermal analysis (DMTA) and Differential Scanning Calorimetry (DSC) are [...] Read more.
In this contribution, the influence of the reaction injection moulding process on the thermomechanical material behaviour of aliphatic hexamethylene diisocyanate (HDI) based fast curing polyurethane is demonstrated. Uniaxial tensile tests, temperature-frequency dependent dynamic mechanical thermal analysis (DMTA) and Differential Scanning Calorimetry (DSC) are used to show the differences in properties for ten different sets of process parameters. The mould and resin components temperature, the mass flow during the filling process and the residence time during the reaction process of the polyurethane are varied in several stages. Further experiments to determine the molar mass of the molecular chain between two crosslinking points of the polyurethane are used to explain the process influences on the thermomechanical properties. Thus, a direct correlation between manufacturing and material properties is shown. In addition, the mutual effect of the different parameters and their overall influence on the material behaviour is presented. Full article
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Article
Effects of Heat Treatment on Microstructure and Mechanical Properties of AlSi10Mg Fabricated by Selective Laser Melting Process
J. Manuf. Mater. Process. 2022, 6(3), 52; https://doi.org/10.3390/jmmp6030052 - 22 Apr 2022
Cited by 6 | Viewed by 3214
Abstract
AlSi10Mg is the most widely additively manufactured and commercialized aluminum alloy and has been used in this study to analyze the effect of heat treatment on its microstructure and mechanical properties. Although research indicates AlSi10Mg parts produced by selective laser melting have characteristically [...] Read more.
AlSi10Mg is the most widely additively manufactured and commercialized aluminum alloy and has been used in this study to analyze the effect of heat treatment on its microstructure and mechanical properties. Although research indicates AlSi10Mg parts produced by selective laser melting have characteristically very fine microstructures, there is a need for more intensive study to comprehend the effect of heat treatment on the mechanical properties of this alloy by analyzing its microstructure. In this study, AlSi10Mg specimens heat-treated at varying temperatures were analyzed by optical and electron microscopes. Micro-indentation hardness and tensile tests were performed to evaluate mechanical properties while considering the specimen build orientation. Observation shows that it is nearly impossible to completely dissolve the evolved second phase silicon-rich particles, which may have significant effects on the mechanical characteristics. Electron microscopy images show the evolution of iron-rich particles in the Al matrix, which may have a significant influence on the mechanical properties of the alloy. Full article
(This article belongs to the Special Issue Laser-Based Manufacturing II)
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Article
Characterization of the Interaction of Metalworking Fluids with Grinding Wheels
J. Manuf. Mater. Process. 2022, 6(3), 51; https://doi.org/10.3390/jmmp6030051 - 21 Apr 2022
Cited by 1 | Viewed by 2186
Abstract
The thermal load that occurs during grinding can be reduced with the aid of an optimized metalworking fluid (MWF) supply. In previous work, mainly the free jet was considered for the determination of the conditions required for an optimized MWF supply. An investigation [...] Read more.
The thermal load that occurs during grinding can be reduced with the aid of an optimized metalworking fluid (MWF) supply. In previous work, mainly the free jet was considered for the determination of the conditions required for an optimized MWF supply. An investigation of the interaction area between the MWF and the grinding wheel has not yet been carried out due to the lack of suitable measurement techniques. In the presented work, both the free jet and the interaction area are analyzed with the aid of new metrological analysis and evaluation methods based on high-speed records (shadowgraphy and shadogram imaging velocimetry) in order to assess the free jet geometry and velocities, as well as the velocity distribution and the MWF amount in the interaction area. Using this approach, the following main results were derived: (1) The free jet velocity remains approximately constant in a defined free jet cross-section even at high distances from the nozzle outlet. (2) The velocity distribution in the interaction area is mainly influenced by the flow rate. (3) A new image parameter (black pixel fraction) was derived for the evaluation of the MWF supply to the contact zone. Full article
(This article belongs to the Topic Modern Technologies and Manufacturing Systems)
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Article
Experimental and Numerical Investigations of the Deep Rolling Process to Analyze the Local Deformation Behavior of Welded Joints
J. Manuf. Mater. Process. 2022, 6(3), 50; https://doi.org/10.3390/jmmp6030050 - 20 Apr 2022
Cited by 3 | Viewed by 1701
Abstract
Welded joints show a comparably low fatigue strength compared to the base material. Thus, different post-weld treatment methods are used to enhance the fatigue strength of welded joints. A promising method to enhance the fatigue strength of metallic components is the deep rolling [...] Read more.
Welded joints show a comparably low fatigue strength compared to the base material. Thus, different post-weld treatment methods are used to enhance the fatigue strength of welded joints. A promising method to enhance the fatigue strength of metallic components is the deep rolling process, but this has rarely been applied to welds. For the qualification of the deep rolling process as an effective post-weld treatment method, knowledge about its influence on the surface and subsurface properties at the fatigue critical weld toe is necessary. Here, geometrical and metallurgical inhomogeneities lead to complex contact states between deep rolling tools and weld toes. Thus, for a first analysis of the local deformation behavior during deep rolling of welded joints, experimentally and numerically generated deep rolling single tracks are compared. Cyclic strain-controlled tests to determine the material behavior were carried out for the numerical analyses using finite element simulation. The presented study shows that it is possible to describe the local deformation of welded joints during deep rolling using finite element simulation. A correct depiction of material behavior is crucial for such an analysis. It was shown that certain irregularities in material behavior lead to lower coincidences between simulation and experiment, especially for the investigated welds, where only low differences in hardness between base material, heat-affected zone, and filler material were found. Full article
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Article
Fabrication of Punch and Die Using Plasma-Assisted 3D Printing Technology for Piercing Sheet Metals
J. Manuf. Mater. Process. 2022, 6(3), 49; https://doi.org/10.3390/jmmp6030049 - 20 Apr 2022
Viewed by 1980
Abstract
A pair of punch and die was often fabricated using subtractive manufacturing processes such as milling and other machining processes. However, additive manufacturing could be used to perform the same processes. This study explored this possibility. In particular, this study fabricated a pair [...] Read more.
A pair of punch and die was often fabricated using subtractive manufacturing processes such as milling and other machining processes. However, additive manufacturing could be used to perform the same processes. This study explored this possibility. In particular, this study fabricated a pair of T-shaped punch and die made of AISI316L austenitic stainless steel using an additive manufacturing process called plasma-assisted 3D printing. Accordingly, T-shaped negative and positive 2D patterns were screen-printed onto the mirror-polished surfaces of the substrates made of AISI316L austenitic stainless steel. The printed film worked like a mask to prevent the printed substrate surfaces from nitriding. In order to form a thick nitrided layer, the unprinted substrate surfaces were selectively nitrided at 673 K for 14.4 ks. The un-nitrided segments of the substrates were uniformly removed by sand-blasting that involved shooting silica particles on the substrate’s surfaces. As a result, the substrates printed with negative and positive T-shaped patterns were transformed into the punch head and die cavity. In order to see the efficacy of the fabricated punch and die pair, this pair was used for piercing the electrical steel sheets under a controlled clearance. Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX) was used to measure surface topography after piercing. In addition, SEM and a 3D profilometer were used to measure the punch and die profiles after piercing. The abovementioned measurement results showed that the fabricated punch and die exhibited highly accurate piercing behavior. Thus, the plasma-assisted 3D printing was useful for punch and die fabrication. Full article
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