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A 1D model describing the dynamics of an injection moulding machine and the injection process is presented. The model describes an injection cylinder actuated by a dual-pump electro–hydraulic speed-variable drive and the filling, holding and cooling phases of the injection moulding process utilising amorphous polymers. The model is suggested as the foundation for the design of model-based pressure controllers of, e.g., the nozzle pressure. The focus is on using material, mould and machine properties to construct the model, making it possible to analyse and design the dynamic system prior to manufacturing hardware or conducting experiments. Both the presented model and the developed controller show good agreement with experimental results. The proposed method is general in nature and enables the design, analysis and evaluation of the machine, material and mould dynamics for controller design based solely on the physical properties of the system. [ABSTRACT FROM AUTHOR]

The filling efficiency during the hot embossing process at micro scale is essential for micro-component replication. The presence of the unfilled area is often due to the inadequate behavior law applied to the embossed materials. This research consists of the identification of viscoplastic law (two-layer viscoplastic model) of polymers and the optimization of processing parameters. Mechanical tests have been performed for two polymers at 20 °C and 30 °C above their glass transition temperature. The viscoplastic parameters are characterized based on stress–strain curves from the compression tests. The influences of imposed displacement, temperature, and friction on mold filling are investigated. The processing parameters are optimized to achieving the complete filling of micro cavities. The replication of a micro-structured cavity has been effectuated using this process and the experimental observations validate the results in the simulation, which confirms the efficiency of the proposed numerical approach. [ABSTRACT FROM AUTHOR]

Producing sustainable microfluidic devices on a large scale has become a trend in the biomedical field. However, the transition from laboratory prototyping to large-scale industrial production poses several challenges due to the gap between academia and industry. In this context, prototyping with a mass production approach could be the novel strategy necessary to bridge academic research to the market. Here, the performance of polymer inserts to produce PMMA microfluidic devices using the microinjection moulding process is presented. Inserts were fabricated with an additive manufacturing process: material jetting technology. The importance of the inserts' orientation on the printing plate in order to produce samples with more uniform thickness and lower roughness has been demonstrated using a flat cavity insert. In addition, preliminary tests were carried out on microstructured inserts with inverted channels of various cross-section shapes (semi-circular or trapezoidal) and widths (200 or 300 µm) in order to investigate the microstructures' resistance during the moulding cycles. The best geometry was found in the channel with the trapezoidal cross-section with a width equal to 300 µm. Finally, a preliminary microfluidic test was performed to demonstrate the devices' workability. [ABSTRACT FROM AUTHOR]

During the process of forming carbon fiber reinforced plastics (CFRP) in an autoclave, deeply understanding the global sensitivity of factors influencing mold surface temperature is of paramount importance for optimizing large frame-type mold thermally and enhancing curing quality. In this study, the convective heat transfer coefficient (CHTC), the thickness of composite laminates (TCL), the thickness of mold facesheet (TMF), the mold material type (MMT), and the thickness of the auxiliary materials layer (TAL) have been quantitatively assessed for the effects on the mold surface temperature. This assessment was conducted by building the thermal–chemical curing model of composite laminates and utilizing the Sobol global sensitivity analysis (GSA) method. Additionally, the interactions among these factors were investigated to gain a comprehensive understanding of their combined effects. The results show that the sensitivity order of these factors is as follows: CHTC > MMT > TMF > TCL > TAL. Moreover, CHTC, MMT, and TMF are the main factors influencing mold surface temperature, as the sum of their first-order sensitivity indices accounts for over 97.3%. The influence of a single factor is more significant than that of the interaction between factors since the sum of the first-order sensitivity indices of the factors is more than 78.1%. This study will support the development of science-based guidelines for the thermal design of molds and associated heating equipment design. [ABSTRACT FROM AUTHOR]

The article presents the results of modeling various modes of vacuum infusion molding of thin-walled polymer-composite structures of arbitrary geometry. The small thickness of the manufactured structures and the fixation of their back surface on the rigid surface of the mold made it possible to significantly simplify the process model, which takes into account the propagation of a thermosetting resin with changing rheology in a compressible porous preform of complex 3D geometry, as well as changes in boundary conditions at the injection and vacuum ports during the post-infusion molding stage. In the four modes of vacuum-infusion molding studied at the post-infusion stage, the start time, duration and magnitude of additional pressure on the open surface of the preform and in its vacuum port, as well as the state of the injection gates, were controlled (open–closed). The target parameters of the processes were the magnitude and uniformity of the distribution of the fiber volume fraction, wall thickness, filling of the preform with resin and the duration of the process. A comparative analysis of the results obtained made it possible to identify the most promising process modes and determine ways to eliminate undesirable situations that worsen the quality of manufactured composite structures. The abilities of the developed simulation tool, demonstrated by its application to the molding process of a thin-walled aircraft structure, allow one to reasonably select a process control strategy to obtain the best achievable quality objectives. [ABSTRACT FROM AUTHOR]

While the filling stage has the least time during the metal casting process, its influence on the casting quality can be remarkable. In gravity casting, the design and dimensions of the filling system determine the filling rate, metal velocity, and the possibility of surface turbulence, where the reliability of casting is mainly impressed by these parameters. In this study, finding an appropriate filling system for a hollow cylinder is examined by investigating the effect of the ingate size, shape, and geometry on the flow characteristics of the molten metal. Simulations are performed investigating the initial filling stages and their repercussions. Three different bottom-gating filling systems are proposed with rectangular, fan, and ring ingate shapes. To compare the filling pattern, metal velocity, and air entrainment of three different filling systems, ProCAST, a CFD simulation software, is used. Results indicated that fan ingate shape successfully introduced less turbulent flow than rectangular ingate shape, causing a reduction in air entrainment. Moreover, results showed that using ring ingate, with sufficient total ingate cross section and taking advantage of the uphill metal flow, can reduce metal velocity entering the cavity as well as eliminate air entrainment. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a solvent‐free polylactic acid (PLA) open‐cell porous scaffold for bone tissue engineering using compression molding and a new chemical foaming compound, that we named CFCO. The latter is composed of a blend of PLA and azodicarbonamide (ADA) as a chemical foaming agent, with the addition of chitosan‐grafted PLA (CS‐g‐PLA) copolymer at various concentrations. The novelty of this approach is that during the foaming, that is, during the decomposition of the ADA foaming agent, the CS‐g‐PLA copolymer is projected toward the surface of the pores and strongly adhere there, which was confirmed by scanning electron microscopy and confocal microscopy. The results showed that at 6.90 wt% of CS‐g‐PLA copolymer, the immobilization of the latter on the surface of the pores led to a 52% increase in cell proliferation compared to the pure PLA control sample and a 26% increase compared to scaffolds that had 10 wt% of CS‐g‐PLA copolymer dispersed throughout the entire PLA matrix. [ABSTRACT FROM AUTHOR]

In this investigation, the method of minimum quantity lubrication (MQL) is utilized in the procedure of finishing milling of AISI H11 steel instead of the conventional lubrication method. The variants are three three-level experimental cutting parameters, including V c -cutting speed, f z -feed per tooth, and a p -depth of cut. The responses are production rate (MRR, in mm3/min), cutting force ( F c , in N), and surface roughness ( R a , in μ m). The purpose of this study is to generate the mathematical regression models for the responses ( R a , F c , and MRR), and solve the multi-objective optimization problem to estimate the appropriate input parameters respecting the defined criteria for F c , R a , and MRR. Experimental research was conducted with an experimental matrix designed by Box–Behnken Design (BBD). The experimental runs were executed on a 5-axis CNC machine tool, model DMU50. The desirability function (DF) method is used to resolve the problem of multi-attribute optimization. The results show that the optimum process variables include V c = 2 1 0 m/min, f z = 0. 0 5 9 mm/tooth, a p = 0. 1 9 6 mm, corresponding to R a = 1. 8 1 9 μ m, F c = 1 5 2 , 3 2 6 N, and MRR = 1 2 9 9. 1 7 7 mm3/min. [ABSTRACT FROM AUTHOR]

The surface quality of plastic parts produced by the conventional extrusion blow molding (EBM) process is usually poor, especially for those made of engineering thermoplastics. To achieve a high-gloss appearance, some costly and pollutive post-treatments (e.g., painting, polishing, etc.) have to be employed to hide or eliminate surface defects. Herein, a variable mold temperature EBM (i.e., variotherm EBM) technology with electric heating and water cooling, which has the potential to directly yield high-gloss parts, was developed. First, the process principle was designed and presented. Then, an complex industrial plastic part, i.e., automotive spoiler, was selected as a molding case to be studied, in which the variotherm blow mold of the spoiler was designed and especially the design rationality of the mold electric-heating and cooling systems was then examined by numerically evaluating the mold thermal response in the respect of cavity surface heating/cooling efficiencies and uniformity. Finally, the variotherm EBM experiments based on the manufactured prototype spoiler mold were conducted. The results showed that the developed technology can realize high-temperature blow molding with both the molding cycle time and energy consumption in an acceptable range compared with the conventional EBM. Moreover, the surface quality of the molded spoilers is largely improved and the surface defects that are generally appearing in the conventional EBM process can be fully eliminated. Thus, the feasibility and effectiveness of developed technology in yielding high-gloss blow-molded parts are demonstrated. [ABSTRACT FROM AUTHOR]

The present investigation was focused on designing and developing Narmada riverbed sand (NRS) as an alternative to commercial-grade silica sand (CGSS) for the green sand mold casting process. The green NRS mold constituents were modeled and optimized through response surface methodology (RSM) to achieve the mold's desired physical and mechanical properties. The RSM model predicted the optimum constituents of NRS mold and found it to be 4.4 wt% moisture, 11.7 wt% bentonite, and 3.9 wt% coal dust to achieve the desired mold properties. The properties of NRS mold, such as mold hardness, permeability number, compressive strength, and shear strength, were found to be 88, 209, 1.6 kg/cm2 (0.156 MPa), and 0.38 kg/cm2 (0.037 MPa), respectively. A laboratory trial of aluminum-silicon alloy (A356) cuboid casting was conducted using green NRS and CGSS mold. The as-cast dimensions, surface roughness, hardness, and microstructure were evaluated and compared. It is observed that the NRS mold is suitable for A356 alloy casting. However, the recyclability of Narmada riverbed sand may be studied further to understand its commercial use as an alternative material to CGSS for non-ferrous alloy casting in Indian foundries. [ABSTRACT FROM AUTHOR]

Introduction: Steel foundries are significant pollution sites with manual molding and demolding processes, therefore technology has moved on to molding using self-fragrance resins. In this paper, the Life Cycle Analysis (LCA) methodology is applied to evaluate the environmental impacts in a foundry process subject to this technological investment. Objetive: To evaluate the environmental impact of a technological proposal in the molding stage in a steel foundry. Materials and Methods: The input and output flows of the mixtures of sand, gases and solid waste in the traditional molding and chemical molding processes for the production of one ton of steel, as a functional unit, were evaluated and inventoried. SimaPro 8.0 software was used to obtain LCA results. Results and discussion: The results demonstrate the economic and environmental feasibility of chemical molding. In the analysis, it was verified that the return sand is the raw material with the greatest benefit to the impact categories, favoring from climate change to human health and limiting the formation of particles that affect health, ecosystems and natural resources. Conclusions: The LCA methodology quantifies the environmental impacts of steel production and justifies the economic-environmental feasibility of chemical molding, verifying that the return sand is the raw material with the greatest contribution to the impact categories and, as an avoided product that is recycled, favors in the new technology the environmental and damage categories. [ABSTRACT FROM AUTHOR]

Rubber tires, as an important part of automobiles, are produced by molding operation under molten temperature and high pressure. However, mold fouling during the vulcanization process is a rock-ribbed problem that not only leads to the loss in productivity and degradation of product quality but also results in severe accidents and enormous economic losses. In this work, a promising Co-Mo/CeO2 composite coating was electroplated and investigated to solve the mold fouling problem. The effect of CeO2 content on the surface morphology, microstructure, hardness, tribological and electrochemical behavior is systematically studied. With an addition of 10 g/L CeO2, the Co-Mo/CeO2 composite coating not only possesses the highest microhardness, the best wear and corrosion resistance but also features hydrophobicity and remarkable mold antifouling performance. This study offers a new strategy for producing composite coatings with excellent performance to reduce mold fouling in practical tire industry applications. Co-Mo/CeO2 composite coatings with excellent corrosion and wear resistance as well as low surface energy were simply electrodeposited and applicated for antifouling in tire mold for the first time. [ABSTRACT FROM AUTHOR]

Injection moulding process stability is a key issue in ensuring suitable quality of plastic parts. External factors such as processing equipment malfunctions, environmental variations, or tool misuse require qualified professionals to handle the issue or diagnosing systems to detect them at an early stage to avoid production in unsuitable processing conditions. The process control system was developed to provide a solution to these problems, whether by introducing automatic self-corrections to processing conditions or providing key performance indicators (KPI) for operation, maintenance, production, and quality control, with a local or remote interface. The system gathers processing and operating data from the mould and from the processing equipment to provide an overall process view. The data collected are obtained from several sensors located on the mould, placed at strategic locations, and real-time information is provided by the injection equipment or its peripherals. These data are processed in near real-time by the process control system and corrections for processing parameters, if required, are transferred to the injection equipment to be implemented in the subsequent injection cycles. Preliminary results from this case study proved that this solution provided suitable responses to the imposed processing variations, resulting in optimized plastic parts. [ABSTRACT FROM AUTHOR]

The temperature distribution of the mold is directly linked to the manufacturing quality of the composite component. In this paper, a bionic mold based on the analysis of a manta ray in swimming is developed to improve the thermal performance of the mold during the autoclave curing process. The bionic mold has fewer frames and better air permeability, and the mold weight is decreased by 42.95% while the stiffness is proved to satisfy the requirement. The model of the autoclave curing process which is verified by experiments is established to carry out the thermal analysis of the mold. Results show that the air velocity in the mold is increased with the bionic design, which can reduce not only the maximum temperature difference of the mold plate (−30.35%) but also the percentage of low-temperature areas. Besides, the heating rate and the heat preservation time of the mold are also improved. [ABSTRACT FROM AUTHOR]

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In this paper, a mold electromagnetic stirring (M-EMS) model was established to investigate the behavior of M-EMS for round bloom castings under different conditions, and an electromagnetic-flow-heat transfer-solidification coupling model was established to explore the problem of eccentric stirring for various formats of round blooms. The results show that the magnetic flux density decreased with the increase in the current frequency, but the electromagnetic torque increases first and then decreases with it, and the same structure of M-EMS for round blooms has the same optimal current frequency at any current intensity. The electromagnetic torque and electromagnetic force both increase as a quadratic function of the current intensity, and the electromagnetic torque, which drives the steel flow, can directly characterize the real M-EMS performance. The mold copper tube has a significant magnetic shielding effect on M-EMS, the stirring intensity decreases rapidly as the tube thickness increases, and the optimal stirring frequency decreases as well. In fact, the deviation between the stirrer center and the geometric center of the strand can result in the eccentric stirring phenomenon. When blooms with a section size of Φ350 mm are produced by Φ650 mm SMS-Concast casting machine, the upper region of the inner arc side and the lower region of the outer arc side are subject to a stronger washing effect, which makes the temperature of the inner and outer arcs show alternating differences. The jet flow from the five-port nozzle can suppress the difference in initial solidification symmetry between the inner and outer arcs of round blooms caused by eccentric stirring. This paper reveals the magnetic shielding effect of the mold copper tube and the magnetic field loss of the air between the stirrer and the inner and outer arcs of the copper, which lead to the stirring intensity and the eccentric stirring phenomenon. [ABSTRACT FROM AUTHOR]

To solve the problem of shaping nonspecialized polymers, new generation micro- and nanoelectronic technologies are used, for example, nanoimprint lithography. A special case of nanoimprint lithography is soft lithography, which involves the formation of a topology using a soft master mold fabricated by a hard mold imprint. Therefore, the study of hard molds self-manufacturing possibility is an urgent task to fabricate a new generation printed circuit boards with optoelectronic buses made of nonspecialized polymer materials. In order to rationalize the cost of purchasing an expensive soft lithography hard mold, an original technological process for hard mold fabrication based on an SU-8 photoresist is developed and implemented. During the development of the proposed technological process, the reason for the formation of a negative slope (T-topping) of the walls of the soft lithography hard mold is determined. In order to eliminate the negative slope, a series of UV cutoff filters for optical radiation wavelengths less than 350 nm is developed and manufactured. According to the experimental measurements data of the i-line mercury lamp UV radiation intensity of the EVG620 NIL automated alignment and exposure unit, the dependences of the UV radiation intensity attenuation on the developed UV light filter functional layer thickness are plotted for 365 and 400 nm optical wavelengths. The effectiveness of the use of the developed UV filters is proved by eliminating the negative slope during the technological process of manufacturing a test topology of the soft lithography hard mold. Soft lithography will make it possible in the future to create printed circuit boards with a built-in optoelectronic data bus in the form of an array of polymer planar optical waveguides and optical input-output elements. [ABSTRACT FROM AUTHOR]

The structure of mold flux glasses in the system CaO-(Na,Li)2O-SiO2-CaF2 with unusually high modifier contents, stabilized by the addition of ∼4 mol% B2O3, is studied using 7Li, 23Na, 19F, 11B, and 29Si magic-angle-spinning (MAS), and 7Li{19F} and 23Na{19F} rotational echo double-resonance (REDOR) nuclear magnetic resonance (NMR) spectroscopy. When taken together, the spectroscopic results indicate that the structure of these glasses consists primarily of dimeric [Si2O7] −6 units that are linked to the (Ca,Na,Li)-O coordination polyhedra, and are interspersed with chains of corner-shared BO3 units. The F atoms in the structure are exclusively bonded to Ca atoms, forming Ca(O,F)n coordination polyhedra. This structural scenario is shown to be consistent with the crystallization of cuspidine (3CaO⋅2SiO2⋅CaF2) from the parent melts on slow supercooling. The progressive addition of Li to a Na-containing base composition results in a corresponding increase in the undercooling required for the nucleation of cuspidine in the melt, which is attributed to the frustrated local structure caused by the mixing of alkali ions. [ABSTRACT FROM AUTHOR]

Mobile millimeter and centimeter scale robots often use smart composite manufacturing (SCM) for the construction of body components and mechanisms. The fabrication of SCM mechanisms requires laser machining and laminating flexible, adhesive, and structural materials into small-scale hinges, transmissions, and, ultimately, wings or legs. However, a fundamental limitation of SCM components is the plastic deformation and failure of flexures. In this work, we demonstrate that encasing SCM components in a soft silicone mold dramatically improves the durability of SCM flexure hinges and provides robustness to SCM components. We demonstrate this advance in the design of a flapping-wing robot that uses an underactuated compliant transmission fabricated with an inner SCM skeleton and exterior silicone mold. The transmission design is optimized to achieve desired wingstroke requirements and to allow for independent motion of each wing. We validate these design choices in bench-top tests, measuring transmission compliance, kinematics, and fatigue. We integrate the transmission with laminate wings and two types of actuation, demonstrating elastic energy exchange and limited lift-off capabilities. Lastly, we tested collision mitigation through flapping-wing experiments that obstructed the motion of a wing. These experiments demonstrate that an underactuated compliant transmission can provide resilience and robustness to flapping-wing robots. [ABSTRACT FROM AUTHOR]

Microchannels are the essential elements in animals, plants, and various artificial devices such as soft robotics, wearable sensors, and organs-on-a-chip. However, three-dimensional (3D) microchannels with complex geometry and a high aspect ratio remain challenging to generate by conventional methods such as soft lithography, template dissolution, and matrix swollen processes, although they are widespread in nature. Here, we propose a simple and solvent-free fabrication method capable of producing monolithic microchannels with complex 3D structures, long length, and small diameter. A soft template and a peeling-dominant template removal process are introduced to the demoulding process, which is referred to as soft demoulding here. In combination with thermal drawing technology, microchannels with a small diameter (10 µm), a high aspect ratio (6000, length-to-diameter), and intricate 3D geometries are generated. We demonstrate the vast applicability and significant impact of this technology in multiple scenarios, including soft robotics, wearable sensors, soft antennas, and artificial vessels. Microchannels are the essential elements for the design of artificial devices but the fabrication of three dimensional (3D) microchannels with complex geometry and a high aspect ratio remains challenging. Here, the authors demonstrate a simple and solvent-free fabrication method capable of producing monolithic microchannels with complex 3D structures, long length, and small diameter. [ABSTRACT FROM AUTHOR]

Polymer surfaces are increasingly being functionalized with micro- and nano- surface features using mass replication methods such as injection moulding. An example of these are microneedle arrays, which contain needle-like microscopic structures, which facilitate drug or vaccine delivery in a minimally invasive way. In this study, the replication fidelity of two types of solid polycarbonate microneedles was investigated using injection compression moulding and conventional injection moulding. Using a full factorial design of experiments for the injection moulding process, it was found that the volumetric injection rate had the largest positive effect on the replication fidelity. The mould temperature and holding pressure were also found to have a positive effect, while the effect of the melt temperature was found to be insignificant for the considered temperature range. For the injection compression moulding process, it was found that a larger compression stroke resulted in a better replication fidelity. A comparison between the replication fidelity for the injection moulding and injection compression moulding indicated that the injection compression moulding process resulted in a higher and more uniform replication fidelity. Using finite element flow simulations, a higher and more evenly distributed cavity pressure was observed compared to the conventional injection moulding process. [ABSTRACT FROM AUTHOR]

The contact interface friction between the specimen and the mold during the stretch-bend is a complex interactive process. Friction causes the uneven distribution of tensile stress on the specimen, which affects the plastic flow of the forming material and the spring-back after forming. In this paper, the analytical model of frictional shear stress and tensile stress distribution in the contact mold segment of the stretch and bend synchronous loading stage was established. The influence law of friction coefficient and contact mold angle on the stress–strain distribution of the specimen contact mold segment was discussed. The effect of key factors affecting the friction state of the contact interface (mold surface roughness and contact mold angle) on the shrinkage deformation of the cross-section and the tensile deformation gradient of the specimen was analyzed by equivalent stretch-bend forming experiments. The results showed that the smaller the surface roughness of the mold was, the better the friction state of the contact interface was, the plastic deformation of the specimen was more uniform, and the difference between the section shrinkage and elongation of the contact mold segment and the suspension segment was smaller. Reducing the contact mold angle of the stretch-bend can bring down the tensile stress difference at both ends of the contact mold segment of the specimen so that the section shrinkage and tensile elongation of the contact mold segment and the suspension segment tend to be consistent. [ABSTRACT FROM AUTHOR]

The build-up welding repair belongs to the typical wire arc additive manufacturing technology, and can effectively repair the mold, significantly extend the life of the mold, is widely used in the field of mold repair. In this study, Cr12MoV cold work mold steel was repaired using wire arc additive manufacturing. Three build-up welding layers Ni625 (Inconel 625) layer, D322 (CrWMoV steel) layer, and Ni625/D322 double-layer composite build-up layer were designed on the Cr12MoV surface. Temperature field simulation and thermodynamic simulation calculations were used to provide the theoretical basis for microstructural analysis of the build-up welding specimens. The practicality of D322 build-up joint is best. The microstructure of D322 build-up joint is D322 layer (acicular martensite)/PHZ (the fusion zone)/HAZ (the heat-affected zone) Ⅰ (Ld + carbides)/HAZ Ⅱ (martensite + residual austenite + carbides (primary + spherical)/HAZ Ⅲ (martensite + lower bainite)/HAZ Ⅳ (tempered sorbite)/BMZ (the base material). The gradient of hardness distribution in different zones of the D322 build-up joint is the smallest, and the hardness of martensite D322 layer is the highest (702 HV), with the best wear resistance (the friction coefficient and the mass loss are lowest). Moreover, D322 build-up joints in the D322 layer and HAZ Ⅱ brittle fracture, shear strength of 464 MPa. The application of this technology can effectively repair Cr12MoV cold work mold steel and provide guidance for the mold repair industry. • Build-up welding layer D322 can effectively repair Cr12MoV cold work mold steel. • The hardness of D322 layer is 702 HV and the gradient of hardness distribution in the D322 build-up joint is the smallest. • D322 build-up joint in the D322 layer and HAZ Ⅱ brittle fracture, shear strength of 464 MPa. [ABSTRACT FROM AUTHOR]

The design and manufacturing of concrete elements need to be reconsidered in light of current trends in architectural geometry. Today, there is a movement toward greater customization and adaptability of concrete elements using "reconfigurable formworks" and "additive manufacturing." Our study approached the issue of fabricating non-standardized concrete elements from the perspective of a "reconfigurable fabrication platform." Specifically, we developed a method of fabricating geometrically diverse concrete joints by combining flexible pressure-enduring tubes with a rigid mechanism, resulting in an adaptive concrete-casting machine. This platform, which we named "Flexi-node," can be used in conjunction with a relevant fabrication-aware digital design tool. Users can computationally design and fabricate a great variety of concrete joints using just one mold, with a minimum of material waste and with no distortion from hydrostatic pressure as would typically occur in a fully flexible formwork. [ABSTRACT FROM AUTHOR]

Injection molding (IM) is a versatile manufacturing process capable of rapid prototyping and mass-producing high-quality polymer parts. The present study mainly investigates the challenge of designing multiple molding gates on the complex arbitrary part surface in 3D. Currently, this problem is a challenge in mold design and engineering experience still plays an important role in designing the molding gates. To reduce the human intervention in the design process, the present study proposed a novel methodology with the following major steps: 1) using Poisson disk sampling (PDS) to preselect candidate gate locations automatically within the suitable gating region specified by designers; 2) using a space-filling initialization strategy and efficient global optimization to find the optimal gate locations. In the present setting, the molding gate design problem is formalized as a discrete optimization problem. The PDS is employed to construct the discrete solution space and EGO is used to efficiently search through a large solution space for the best design. To further promote optimization efficiency, a parallel implementation of EGO is also proposed. The effectiveness of the proposed methods is validated in two design cases. The results demonstrate the proposed EGO and Parallel EGO method is superior that the Genetic Algorithm (GA) and Surrogate Optimization (SO). Moreover, the proposed Parallel EGO converges faster than all other alternatives. [ABSTRACT FROM AUTHOR]

Hot stamping uses boron (B) steel to simultaneously form parts at high temperatures while cooling the parts in a mold, which is advantageous because of the ability to freeze the forms. However, compared to conventional cold forming, this technique requires additional facilities that include heating devices and additional time for cooling after forming at high temperatures. Additionally, because of the high strengths of hot stamping parts, shear process operations after molding tend to be difficult to perform as a continuous operation via press processing; thus, most operations depend on separate laser processing, which results in lower productivity and increased manufacturing costs. This limitation continues to be the most significant problem with this technology, therefore, restricting its commercialization because of increased mold manufacturing costs and durability problems. This study investigated a low-cost, high-functionality shear mold manufacturing method for 1.5 GPa grade hot-stamped components using heterogeneous metal additive manufacturing. After the concentrated stress in steel during the shearing processes was analyzed using a multi-physical analysis, metal additive manufacturing was used to fabricate the shear mold. Its life was evaluated through trial molding and compared with that for conventional technology. Finally, the commercialization potential of the newly developed method was assessed. [ABSTRACT FROM AUTHOR]

The bulk Fe-B-M (M = Si, Cu) ternary eutectic alloys with nano-lamellar structure and excellent soft magnetic properties were successfully prepared by undercooling combined with Cu-mold casting. Different effects of Si and Cu elements on the structural refinement and soft magnetic properties were studied. The results show that the lamellar spacing can be decreased to less than 50 nm with addition of Si or Cu of 1 at. % into the Fe-B eutectic alloy. Based on the classical random anisotropy model, a quantitative correlation between the intrinsic coercivity (HC) and the lamellar spacing (λ) was also obtained. [ABSTRACT FROM AUTHOR]

The article focuses on challenge of equipping devices and components with more functions while at the same time makes them more compact, smaller and lighter has increased rapidly in recent years. Topics include examines more and more assemblies consist of lightweight plastic housings that are produced by injection molding and considered metal parts stabilize these assemblies and systems and ensure the overall function.

The production of rapid tools for plastic molding, sheet metal forming, and blanking has always been a critical and important goal for applied research, and a very large number of alternative methods have been proposed over the decades for their production. Among these methods, the use of extrusion-based additive manufacturing (EAM), such as fused filament fabrication (FFF) or similar technologies, has not been frequently considered and needs to be explored extensively. EAM is generally considered a low-cost, low-quality, low-performance class of AM and not suited to produce real functional parts, but only for aesthetical prototypes. However, the capabilities of EAM technologies have greatly evolved and now it is possible to extrude a wide range of materials such as polymeric materials including both the low strength polymeric materials (such as nylon or PLA) and the high strength polymeric materials (such as PEI and PEEK), metals (such as tool steel), and even ceramics (such as zirconia). Starting from an extensive literature review, the purpose of the present paper is to further demonstrate the potential applicability and versatility of EAM as a rapid tool manufacturing technology for different applications in shearing, bending, deep drawing, and injection molding. [ABSTRACT FROM AUTHOR]

In this work, polypropylene (PP) was foamed via rotational molding using a chemical blowing agent (CBA) based on azodicarbonamide over a range of concentration (0 to 0.5% wt.). The samples were then analyzed in terms of morphological, thermal and mechanical properties. The morphological analysis showed a continuous increase in the average cell size and cell density with increasing CBA content. Increasing the CBA content also led to lower foam density and thermal conductivity. Similarly, all the mechanical properties (tension, flexion and impact) were found to decrease with increasing CBA content. Finally, the efficiency of the rotomolding process was assessed by producing neat PP samples via compression molding. The results showed negligible differences between the rotomolded and compression molded properties at low deformation and rate of deformation indicating that optimal rotomolding conditions were selected. [ABSTRACT FROM AUTHOR]

Microneedles are able to penetrate into the skin and offer great chances in various biomedical applications including transdermal drug delivery, stable bio-signal monitoring, sampling and bio-sensing. Owing to the micro-scale feature size, microneedles have advantages of minimal invasiveness, pain, high biosafety and simple operation. However, it is still challenging to fabricate solid microneedles on a flexible substrate. This review primarily introduces recent studies about microneedles on the flexible substrate, various fabrication methods of microneedles on the flexible substrate, including micromolding, silicon dry/wet etching, electrochemical etching, drawing-lithography, electro-drawing lithography, magnetorheological drawing lithography, three-dimensional printing, vapor–liquid–solid grown, hot embossing, and assembly, and corresponding materials have been summarized and discussed in details. In the end, regular biomedical applications of microneedle on the flexible substrate are categorized into drug delivery, vaccine delivery, electrophysiological interaction, sampling and bio-sensing. Recent advances of each application have been discussed. [ABSTRACT FROM AUTHOR]

Conformal cooling channels (CCCs) are a cooling passageway which follows the profile of the mold cavity or core to perform uniform cooling process effectively in the injection molding process. The production cost is closely related to productivity. To further improve productivity, the injection mold was equipped with CCCs to shorten the cooling time of the injection molded part. To investigate the relationship between the cooling channel layout and cooling efficiency of the CCCs, silicone rubber molds (SRMs) with different layouts of cooling systems were designed and constructed in this study. Simulation software was utilized to study the cooling performance. To verify the results of the simulation, SRM with different cooling systems were fabricated for low-pressure wax injection molding. It was found that the cooling time of the injection molded part is indeed affected by the total surface area of the heat exchange between the coolant and the SRM. The cooling system with four inlets and four outlets seems to be the optimum layout of the SRM in the case study in terms of the difficulty of mold making, total surface area of the heat exchange between the coolant and the SRM, and total cooling flow length of each segment. The saving in the cooling time about 2796 s and improvement of cooling efficiency about 76% can be obtained when the SRM with four inlets and four outlets was used for injection molding. The findings in this study can be used as a reference to design CCCs of injection mold built with AM technology. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Traditional studies of archaeological ceramics in Colombia have been largely based on visual and stylistic analyses. Here we introduce frameworks and concepts of reverse engineering as a complementary strategy to develop hypotheses about ceramic manufacture, as a first step to the address possible cross-craft relationships and broader sociocultural parameters affecting technical traditions. Our case study is focused on ceramic figurines recovered from two archaeological sites in southwest Colombia (Inguapí and La Cocotera), both dated to the period of greatest cultural and technological development of the Tumaco tradition (350 BC–AD 350). The results of the analyses including microscopy, XRF, SEM-EDS and XRD revealed two manufacturing pathways within the broader tradition, developed locally and adapted to the natural resources available to each site. These are shown through chemical and mineralogical differences in the raw materials, as well as differences in their preparation and shaping, molding, and modeling processes as observed at the microstructural level. Estimated firing temperatures are under 600°C for La Cocotera, and under 800°C for those of Inguapí, with an inhomogeneous, oxidizing atmosphere probably related to firing in a pit. The superficial characterization shows that all the figurines were painted, with those from Inguapí externally smoothed and polished, and those from La Cocotera covered with a slip. Notwithstanding differences between sites, the ceramic figurines illustrate a particular technical style that undoubtedly conveyed a shared ideological message of cultural affiliation. These results contribute in an innovative way to archaeological ceramic studies in Colombia from a different perspective that is complementary to the more common typological studies. [ABSTRACT FROM AUTHOR]

The solidification structure and macrosegregation are investigated in different current intensities of mold electromagnetic stirring (M‐EMS) and final electromagnetic stirring (F‐EMS) by a series of industrial trials during the 20CrMnTi bloom continuous casting (CC) process. With the current intensity of M‐EMS increasing from 100 to 390 A, the deflection angle of columnar dendrites increases from 25.0 to 32.49 deg. With the current intensity of M‐EMS increasing from 0 to 390 A, the equiaxed crystal ratio increases from 20.4% to 25.7% and center porosity varies little. With the increasing current intensity of M‐EMS, the negative segregation in the subsurface and positive segregation in the columnar‐to‐equiaxed transition (CET) zone deteriorate gradually. The M‐EMS has little effect on the center‐positive segregation, and the center‐positive segregation is maintained at 1.37–1.40. With the current intensity of F‐EMS increasing from 0 to 500 A, the equiaxed crystal ratio is within 25.3–25.8%, and the large center porosities disappear instead of numerous fine spots in the equiaxed zone. The degree of center‐positive segregation decreases from 1.48 to 1.30. For the CC process, to obtain a better internal quality of 20CrMnTi bloom, the optimal current intensities of M‐EMS and F‐EMS are 0 and 500 A, respectively. [ABSTRACT FROM AUTHOR]

This long‐term study explores the development and application of a polymeric composite product with end goal to represent a light‐weight and eco‐friendly alternative to an existing car part, with current paper focusing on product development. Selecting the right constituents for an advanced polymeric composite product, having its end functional role in mind, is the foundation for a good development process. As modelling and simulation are key for predicting, defining and controlling the manufacturing process, the paper includes mathematical modelling and numerical simulations of how the structure performs during the technological process; thus, refining the concept and optimizing the process before producing industrial applications. A few samples of the polymeric composite product are manufactured where glass fibers are used as reinforcement material, due to their reduced specific weight, affordable price and widespread availability. Concrete results consequently include designing, building and testing multiple variations of the polymeric composite product manufactured in semi‐cylindrically shaped samples using a research demonstration mold. Considering obtained results, large‐scale industrial application is envisaged for automotive polymeric composite parts that would be brought to market at competitive prices. [ABSTRACT FROM AUTHOR]

Confinement can modify the dynamics, the thermodynamics, and the structural properties of liquid water, the prototypical anomalous liquid. By considering a generic model for anomalous liquids, suitable for describing solutions of globular proteins, colloids, or liquid metals, we study by molecu-lar dynamics simulations the effect that an attractive wall with structure and a repulsive wall without structure have on the phases, the crystal nucleation, and the dynamics of the fluid. We find that at low temperatures the large density of the attractive wall induces a high-density, high-energy structure in the first layer ("templating" effect). In turn, the first layer induces a "molding" effect on the second layer determining a structure with reduced energy and density, closer to the average density of the system. This low-density, low-energy structure propagates further through the layers by templating effect and can involve all the existing layers at the lowest temperatures investigated. Therefore, al-though the high-density, high-energy structure does not self-reproduce further than the first layer, the structured wall can have a long-range influence thanks to a sequence of templating, molding, and templating effects through the layers. We find that the walls also have an influence on the dynamics of the liquid, with a stronger effect near the attractive wall. In particular, we observe that the dy-namics is largely heterogeneous (i) among the layers, as a consequence of the sequence of structures caused by the walls presence, and (ii) within the same layer, due to superdiffusive liquid veins within a frozen matrix of particles near the walls at low temperature and high density. Hence, the partial freezing of the first layer does not correspond necessarily to an effective reduction of the channel's section in terms of transport properties, as suggested by other authors. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An instrumented hot compression molding apparatus was fabricated to allow real‐time monitoring and precise temperature control during the compaction and consolidation of large polyether ether ketone (PEEK) products. The objective was to determine the impact of controlled variables on the properties of the molded article. Four different strategies were designed to control the mold thermal profiles. The average crystallinity in a commercial molding process is restricted due to large thermal masses with low thermal conductivity. In contrast, this research was able to reduce the crystallinity range from 33% to 6% by developing a special controlled apparatus and implementing new processing methodologies. In this study, PEEK showed a significant increase in the modulus compared to typical values measured on commercially produced analogs, and a higher degree of property uniformity. In a single commercially molded PEEK billet, compressive modulus variability was 13% at room temperature, and 21% at 225°C. Properties of billets produced using the laboratory apparatus showed a reduction in variability to 2%. [ABSTRACT FROM AUTHOR]

In 2019, the ice restaurant at the 21st Harbin Ice and Snow World is one of the representative works of contemporary Chinese ice shell architecture. Through the summary of practical experience of the ice restaurant. The design thinking and practice method of coordination between architecture and structure of large complex ice shell are elaborated in detail. The logic and advantages of air-ribbed inflatable mold construction method, numerical simulation optimization process based on Grasshopper platform and structural performance calculation of ABAQUS platform are included. The feasibility of collaborative design method in the design of ice shell building is proved. It promotes the development of ice shell construction. On the basis, the future development direction is prospected. [ABSTRACT FROM AUTHOR]

If the process‐induced distortions (PIDs) of asymmetrical laminates can be predicted accurately and tailored at the early design stage, the production of curved panels from flat molds could be an attractive technique in a cost‐driven production environment. A data‐driven computational methodology which integrates the finite element method (FEM) and artificial neural network (ANN) is presented to rapidly predict the maximum PID and to perform high‐throughput screening of thermosetting‐matrix composites of an asymmetrical laminate for a targeted maximum PID. We performed a grid search on ANN architectures and hyper‐parameters using cross‐validation and obtained a well‐trained ANN model with high generalization performance. For the forward problem, the ANN model was adopted to predict the maximum PIDs of CYCOM X850 and CYCOM 977‐2 prepregs, which were subsequently verified experimentally. For inverse design, a large‐scale screening method based on the ANN model was utilized to determine the candidates for a targeted maximum PID, with an experimental demonstration using one of these candidates. The well‐trained ANN model provides an alternative approach to faster computation with high accuracy for the maximum PID prediction and further guides the discovery of materials with desired distortion behaviors. [ABSTRACT FROM AUTHOR]

In compression molding using glass-fiber-mat-reinforced thermoplastic (GMT) sheets, a slightly longer compression waiting time from sheet placement on a lower mold to the start of sheet compression by an upper mold can cause incomplete filling due to a decrease in the sheet temperature. However, precise measurement techniques for compression waiting time have not been sufficiently established. A monitoring system was produced that includes pressure—temperature sensors mounted in a compression mold that can simultaneously measure the pressure and temperature of one local surface. Two types of distance sensors were also used to measure upper mold motion widely and precisely. Determination of compression waiting time was attempted by measuring the moment when the lower mold temperature slightly increases in response to contact with the melted GMT sheet and the moment when the melt pressure increases in response to compression by an upper mold. The results showed that compression waiting time could be precisely calculated using the profile data obtained. Moreover, it was also possible to observe the melt pressure overshoot that occurs depending on sheet stacking patterns and mold cavity shape, although in some cases, the overshoot was not observed. In conclusion, this study has demonstrated that the system is effective in monitoring the compression molding process widely and precisely. [ABSTRACT FROM AUTHOR]

This paper introduces a method of replicating electrical circuits through a series of specific requirements as part of a design methodology referred to as Intrinsically Patterned Electrical Systems (IPES) processing methodology. IPESs are unique in that they allow for replication of a circuit directly using the circuit as a pattern for molding, without the use of an intermediate mold. In this study, the IPES processing methodology requirements have been met by using a set of specific mechanical manipulations and a combination of paraffin wax as a substrate and liquid gallium to form a conductive layer. The intent of the IPES methodology is twofold; it could be used for rapid, lower-cost manufacturing or in the repair of damaged printed circuit boards since the damaged circuit can be replicated through the mechanical manipulations detailed by IPES processing methodology requirements. Specifically, this paper investigates the possibility of IPES methodology to meet manufacturing requirements, which is demonstrated through the conducted computational fluid dynamics (CFD) studies. This paper also includes a short physical example of a simplistic circuit which is replicated using the IPES processing methodology. [ABSTRACT FROM AUTHOR]

The paper deals with the proposal of a new solution for monitoring the mold temperature. The mold is used for the production of thermosetting products by pressing technology. At present, the mold temperature is measured separately at sixteen locations of the mold. This measurement is lengthy and laborious, causing production downtime. At the same time, measurement is physically problematic since the mold has a temperature in the range of 130 to 150 °C. The controller must manually record all measured data in the record and re-write the record to the computer. The new solution is to measure four control points at once. The controller will measure these points and the measured data will be sent online to the system. This method will clearly speed up the measurement process. [ABSTRACT FROM AUTHOR]