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Purpose: Three-dimensional (3D) casting means using additive manufacturing (AM) techniques to print the mould for casting the cast tool. The printed mould, however, should be checked for its dimensional accuracy. 3D scanning can be used for the same. The purpose of this study is to combine the different AM techniques for 3D casting with 3D scanning to produce parts with close tolerance for preparing electrical discharge machining (EDM) electrodes. Design/methodology/approach: The four processes, namely, stereolithography, selective laser sintering, fused deposition modelling and vacuum casting, are used to print the casting mould. The mould is designed in two halves, assembled to form a complete mould. The mould is 3D scanned in two stages: before and after using it as a casting mould. The mould's average and maximum dimensional deviations are calculated using 3D-scanned results. The eutectic Sn-Bi alloy is cast in the mould. The surface roughness of the mould and the cast tool are measured. Findings: The cast tool is selected from the four processes in terms of dimensional accuracy and surface finish. The same is electroplated with copper. The microstructure of the cast tool (low-melting-point alloy) and deposited copper is analysed using a scanning electron microscope. Energy dispersive spectroscopy and X-ray diffraction techniques are used to verify the composition of the cast and coated alloy. The electroplated tool is finally tested on the EDM setup. The material removal rate and tool wear are measured. The performance is compared with a solid copper tool. The free-form customised EDM mould is also prepared, and the profile is cast out. The same is tested on the EDM. Thus, the developed path can be successfully used for rapid tooling applications. Originality/value: The eutectic composition of Sn-Bi is cast in the 3D-printed mould using different AM techniques combined with 3D scanning quality to check its feasibility as an EDM electrode, which is a novel work and has not been done previously. [ABSTRACT FROM AUTHOR]

AlFeCoCrNiTi0.2 Ugh entropy alloy was prepared by vacuum casting and annealed at 600,800 and 1 100 C respectively. The microstructure and mechanical properties of the alloy with different heat treatment temperatures were studied by means of Scanning Electron Microscopy (SEM), energy dispersive analysis(EDS), X- ray diffractometer(XRD), Nano indentation instrument and universal mechanical testing machine. The results show that the as-cast and heat-treated AlFeCoCrNiTi0.2 High-entropy alloys are body-centered cubic structure. After heat treatment,BCC1 predicates BCC2 phase to form a biphasic structure (primary phase BCC1 + precipitated phase BCC2). At 600 C,the hardness of the alloy is 672 HV,the plastic modulus is 655. 7 Gatha pressing depth is 283. 4 nm, the compression plasticity is 28%,and the breaking strength is 1. 75 GA. The hardness of 800 C and 1 100 C alloy decreases, manly due to the decomposition of BCC phase to form a biphasic BCC (BCC1 +BCC2) sold solution structure, which reduces the strength of the alloy. [ABSTRACT FROM AUTHOR]

Vacuum casting (VC) is a promising technique used for the production of functional plastic parts due to its fast production of high-quality prototypes. However, the mechanical properties of the fabricated products are affected by the composition of the molding materials. Additive manufacturing (AM) is also widely applied for low-volume prototyping applications. However, the mechanical properties of the fabricated products are affected by both build directions and printing angles. To investigate the difference in flexural strength of parts between vacuum casting and fused deposition modeling, glass fiber (GF) and carbon fiber (CF) are added to the matrix materials of polyurethane (PU) for improving the flexural strength of the molded products and three different printing angles and two build directions were applied in AM process. It was found that the flexure strength of the specimen fabricated by VC is generally greater than that of the specimen fabricated by AM. The highest flexure strength of the specimen fabricated by VC is 141 MPa, whereas the highest flexure strength of the specimen fabricated by FDM is only 102.7 MPa. The addition of short GF to the PU will increase the flexural strength. The flexural strength can be increased by about 41% when the PU is added with 4 wt.% short GF. The flexural strength can be increased by about 4.8% when the PU is added with 1 wt.% long GF. In contrast to above results, the flexural strength will be reduced when the PU is added with more than 2 wt.% long GF. On the contrary, the flexural strength can not be improved when the short CF or long CF is added to the PU. Finally, the flexural strength of the plastic prototype made by VC technology is superior to that of the plastic prototype made by FDM since the mechanical properties of the plastic prototype made by the FDM are affected by the build direction and printing angle. [ABSTRACT FROM AUTHOR]

Vacuum casting (VC) is a highly versatile manufacturing technique capable of producing parts in a wide range of polymers for end use plastic parts or prototypes. VC technology is ideally suited to low volume batch production compared with plastic injection molding since a silicone rubber mold (SRM) can be used to produce up to fifty to eighty parts. The main challenge of this method is that the both dimensional and form accuracies of the VC parts were affected by the fastening force of the SRM using tape due to the fastening force is inconsistent for different operators. In this study, an intelligent SRM clamping mechanism comprising a pressure sensor and Arduino pressure sensing module was developed for reducing the variations in both dimensional and form accuracies of the VC parts. It was found that the 14 kPa is the optimal clamping pressure. The angular deviation of the cuboid VC parts produced by the intelligent clamping mechanism falls within the range of one standard deviation (SD) to the average. The minimum zone circle deviation of the cylinder VC parts produced by the intelligent clamping mechanism falls within the range of − 1 to 2 SDs. In addition, the production cost of the SRM can further be reduced by about 23% using an intelligent clamping mechanism compared with that using the conventional method. [ABSTRACT FROM AUTHOR]

The article deals with vacuum casting technology and especially with the assessment of the influence of the tempering temperature of silicone molds on the dimensions of future castings. The aim was to evaluate the actual size of the castings, using different tempering temperatures of the molds and different casting materials. After examining the resulting dimensions of the individual castings, a procedure was established by which these effects could be minimized. In the end, a test of the proposed procedure is performed, which confirmed its correctness. [ABSTRACT FROM AUTHOR]

Solar interfacial water evaporation is an environmentally friendly and potential approach to producing fresh water. Herein, a PAN/CNTs-foam (PCF) evaporator with high porosity, hierarchical pore structure, and excellent solar absorption was successfully prepared by the vacuum casting method. The PCF prepared with a CNTs content of 17 % and NaCl particle size of 150–300 μm possessed an evaporation rate of 2.04 kg m−2 h−1 for pure water under 1 sun illumination. The PCF-2 showed a maximum evaporation rate of 5.60 kg m−2 h−1 for real seawater in outdoor experiments, and the quality of the produced clean water was also demonstrated. The purification ability of PCF for organic dyes further confirmed the potential usage in wastewater treatment. Particularly, the PCF-2 exhibited efficient and stable desalination performance for hypersaline water even in 25 wt% simulated brine due to the hierarchical interconnected channels. Our work offers a robust method for the construction of a 3D foam evaporator with hierarchical interconnected channels for efficient and sustainable hypersaline water desalination. [Display omitted] • A 3D PCF evaporator with hierarchical pore structure and controllable pore size was successfully prepared by the vacuum casting method. • The prepared PCF-2 evaporator showed a high evaporation rate and evaporation efficiency. • The PCF-2 evaporator possesses excellent salt resistance and can be for the treatment of hypersaline water. [ABSTRACT FROM AUTHOR]

Hybrid moulds are an increasingly considered alternative for prototype series or short production runs. This type of tools resorts on the use of Rapid Prototyping and Tooling (RPT) to produce the moulding elements (blocks or other inserts). This study was developed using a hybrid injection mould with exchangeable moulding elements that were produced by additive manufacturing (AM), namely vacuum epoxy casting, stereolithography and ProMetal. A full steel tool was also used as a reference. The processing conditions for the polypropylene moulded parts using the hybrid mould were monitored for pressure, temperature and ejection force. The hybrid mould performance was assessed in terms of pressure and temperature evolution during the injection cycle and the AM moulding elements for physical integrity. The data from the polypropylene moulded parts and the moulding inserts are compared with structural and rheological simulations using ANSYS Workbench and MOLDEX 3D. The results show that the hybrid mould performance and the structural integrity of the moulding elements depend on the properties of the materials used. The moulding shrinkage, when resin cores are used, is also affected by the core deformation caused by the injection pressure. [ABSTRACT FROM AUTHOR]

Vacuum casting of polyurethane (PUR) in silicone molds is used industrially for the production of prototypes and small series as well as in various noncommercial research areas. This includes the reproduction of archeological findings, biological samples or electronic devices. In this study, the authors investigate the molding accuracy of different commercial silicones and PUR casting resins both on microscopic and macroscopic scales. For this, they used a variety of master models to generate silicone rubber casting molds. The resulting PUR castings are investigated by helium ion microscopy, confocal laser scanning microscopy, and optical 3D‐scanning. [ABSTRACT FROM AUTHOR]

Vacuum casting is one of the widely used methods for small-volume production of plastic parts. The main challenge of this method is to choose the optimal working parameters to manufacture plastic parts with better mechanical properties. The conventional vacuum casting (CVC) technology uses gravity to make the casing material to fill the mold cavity, resulting in the yield of the molded components with high tensile strength is relatively low. Vacuum differential pressure casting (VDPC) can overcome this disadvantage since the filling mechanism of the casting material is different from CVC process. In this study, integration of design of experiments approach and the VDPC technique was employed to enhance tensile strength of molded components. It was found that the most important control factor affecting the tensile strength of the fabricated component is the mold cavity temperature, followed by the material mixing time, the differential pressure time, and the mixing chamber inlet valve angle. The optimal process parameters for producing components with better tensile strength are the mold cavity temperature of 35 °C, the material mixing time of 40 s, the differential pressure time of 8 s, and the mixing chamber inlet valve angle of 60 °. [ABSTRACT FROM AUTHOR]

Vacuum casting of polyurethane in silicone molds is a widely used method for prototype replication and holds great potential for application in small batch production. Products produced in this way offer extremely good shape accuracy even in the nanometer range and high surface quality, as well as flexible material properties that are convenient for serial production. In this work, we present a new method for increasing the feasible output of silicone casting molds in vacuum casting processes. By supplementation of polyamide 12 powder, which is a waste product of the selective laser sintering process, to the silicone rubber the maximum output of the casting molds could be increased by up to 38.5% while the amount of new silicone used has been substituted by up to 20%. Both generic silicone samples and representative silicone molds have shown that with increasing polyamide content, aging characteristics decrease as the output increases. The improvement was quantified by comparative weight, hardness and thermogravimetric measurements. As surface energy and roughness measurements as well as extensive casting experiments have shown, the silicone surface and thus the product surface remains unimpaired. [ABSTRACT FROM AUTHOR]

Vacuum casting (VC) is the most economical production process for producing small numbers of prototype parts under vacuum conditions. The filling of the casting material in the conventional VC process only depends on the gravity. Thus, some defects of the cast part are observed. In this study, differential pressure (DP) VC was proposed to reduce the filling time and improve the quality of cast parts. In this study, the filling mechanisms in both horizontal and vertical directions were investigated theoretically and experimentally. The actual filling situations of the acrylonitrile butadiene styrene resin in both the horizontal and vertical directions are similar to the simulation results. The relationship of the filling time for DP time, sprue diameters, and mold cavity capacities was investigated. The filling time can be estimated in terms of DP time, sprue diameter, and mold cavity capacity. [ABSTRACT FROM AUTHOR]

Vacuum casting is a widely employed method for small batch production of plastic prototype parts by the use of silicone rubber mold. However, some undesired defects of the cast part such as micro-bubbles, voids, weld lines, shrink mark, sink marks, warpage, blister, or short shot are observed in the conventional vacuum casting process. Vacuum differential pressure casting (VDPC) can overcome these drawbacks because of the filling mechanism of the casting material is different from conventional vacuum casting process. In this study, the VDPC was proposed to enhance the quality of casting parts. The process parameters related to the VDPC are investigated theoretically. Fabrication of components with microstructures using VDPC was investigated experimentally. It was found that the quality of VC parts with microstructures can be improved significantly using the VDPC. The transcription rate of the depth of the Fresnel lens can be increased from 41.9 to 99%. [ABSTRACT FROM AUTHOR]

We present an in-depth investigation of the aging effects in silicone molds for vacuum casting processes. Their lifetime is limited to a few production cycles due to contamination with the diisocyanate component of polyurethane casting materials. Using thermogravimetric analysis measurements, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and helium-ion-microscopy the chemical and physical mechanisms of the aging process have been identified. It has been shown that a diffusion process of diisocyanate into the cavity surface leads to the formation of interpenetrating polymer networks of polyurea derivatives in silicone rubber. This has been proven by extracting and analyzing polyurea of low molecular weights from the silicone. [ABSTRACT FROM AUTHOR]

Highlights • Magnesium foam provides better physical properties. • The optimum parameter combination of casting process has been found. • Particle size can provide higher significant nature on nature of metallic foam. Abstract In the present study, an endeavour has been made to investigate the mechanical properties of hollow glass microspheres reinforced die cast magnesium alloy under vacuum die casting process. The particle size, mass fraction, stirring speed has been considered as input process parameters to analyze the mechanical properties such as hardness, compressive strength, porosity and density of the syntactic foams. Taguchi-Grey relational based multi response optimization has been utilized to compute the optimal process parameters and find the influence of those parameters on performance measures of casting process. From the experimental investigation, the optimal process parameters have been found as particle size (45 microns), mass fraction (20%) and stirring speed (600 rpm) among the chosen process parameters. The highest max–min indicates the particle size has higher influence on determining the mechanical properties of the syntactic foam owing to its importance on determining the porosity. It has been also observed that the density of syntactic foam decreases with increases in the mass percentage of hollow glass microspheres. [ABSTRACT FROM AUTHOR]

It is very meaningful to open the rapid tooling course for improving level of advanced manufacturing practice courses in the engineering training. Based on the problem analysis of existing vacuum casting equipment, considering teaching openness for teachers and convenience and security of operation, numerical controlling vacuum casting laboratory equipment was developed. It has a high automation degree, simple operation and security. The hardware and software structure and features of the device were introduced in detail. The typical practice case was also introduced. The reform injects a new element for the practice of engineering training course, and plays a certain role in promoting teaching reform of the course. [ABSTRACT FROM AUTHOR]

In conditions of dynamic market environment there is an increasing requirement for rapid development and production of complex and functional parts from different materials. In this paper, we present the process of development and production of small batches of functional parts in the integrated system of additive and vacuum casting technology. All advantages of this integrated approach were used during the research. Data obtained from the manufacturer were used for the proper selection of materials and they relate to the value of mechanical characteristics. [ABSTRACT FROM AUTHOR]

An Abdominal Aortic Aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta at least 1.5 times its normal diameter. The criterion of maximum diameter is still used in clinical practice, although numerical studies have demonstrated the importance of other biomechanical factors. Numerical studies, however, must be validated experimentally before they can be clinically implemented. We have developed a methodology for manufacturing anisotropic AAA replicas with non-uniform wall thickness. Different composites were fabricated and tested, and one was selected in order to manufacture a phantom with the same properties. The composites and the phantom were characterized by biaxial tensile tests and a material model was fit to the experimental data. The experimental results were compared with data from the literature, and similar responses were obtained. The anisotropic AAA replicas with non-uniform wall thickness can be used in benchtop experiments to validate deformations obtained with numerical simulations or for pre-intervention testing of endovascular grafts. This is a significant step forward considering the importance of anisotropy in numerical simulations. [ABSTRACT FROM AUTHOR]

Warpage is the most common quality defect in parts produced by vacuum casting (VC). In this paper, the VC process and mold filling mechanism are analyzed, and a mathematical model of the filling process is constructed, incorporating fluid dynamical relationships. The filling process is simulated using a numerical simulation algorithm. A warpage optimization strategy combining response surface methodology (RSM) with the artificial fish-swarm algorithm (AFSA) is then proposed, in which the main function of the RSM is to fit the relationship between process parameters and warpage, while that of the ASFA is to obtain the optimized process parameters. Finally, the implementation of the optimization strategy is presented in detail, together with a specific example, and simulations and a real experiment are carried out. The experimental results verify the accuracy of the model and the reliability of the algorithm. In conclusion, the optimization method can reduce the warpage of VC parts and improve product quality, providing a reliable new low-cost method for optimizing the process parameters in VC technology. [ABSTRACT FROM AUTHOR]

Numerous facts have validated that sharkskin possesses the obvious drag reduction effect in certain turbulent flowing stations, and it has huge potential and important applications in the fields of agriculture, aerospace, industry, transportation, daily life and so on, which have attracted increased attention throughout the world. To meet the increasing requirements of practical applications, it has been progressively developing into an urgent problem to manufacture sharkskin surfaces with perfect forming quality and high drag-reducing effect. In this paper, the vacuum casting method is put forward to fabricate the drag-reducing surface with the real sharkskin morphology by eliminating the air bubbles from the bottom of sophisticated morphology in the pouring process. Meanwhile, a novel and facile 'marking key point' method is explored and adopted to search for the corresponding biological sharkskin and negative template, a more convincing way to evaluate the replicating precision is systematically illustrated and the hydrodynamic experiment is carried out in the water tunnel. The results indicate that wall resistance over sharkskin surface replicated by the vacuum casting method can be decreased by about 12.5% compared with the smooth skin. In addition, the drag reduction mechanism hypotheses of sharkskin are generalized from different respects. This paper will improve the comprehension of the sharkskin fabrication method and expand biomimetic sharkskin technology into more applications in the fluid engineering. [ABSTRACT FROM AUTHOR]

The goal of this work is to develop a framework for manufacturing nonuniform wall thickness replicas of abdominal aortic aneurysms (AAAs). The methodology was based on the use of computed tomography (CT) images for virtual modeling, additive manufacturing for the initial physical replica, and a vacuum casting process and range of polyurethane resins for the final rubberlike phantom. The average wall thickness of the resulting AAA phantom was compared with the average thickness of the corresponding patient-specific virtual model, obtaining an average dimensional mismatch of 180 μm (11.14%). The material characterization of the artery was determined from uniaxial tensile tests as various combinations of polyurethane resins were chosen due to their similarity with ex vivo AAA mechanical behavior in the physiological stress configuration. The proposed methodology yields AAA phantoms with nonuniform wall thickness using a fast and low-cost process. These replicas may be used in benchtop experiments to validate deformations obtained with numerical simulations using finite element analysis, or to validate optical methods developed to image ex vivo arterial deformations during pressure-inflation testing. [ABSTRACT FROM AUTHOR]

This study presents a cost-effective approach for rapid fabricating modeling platforms utilized in fused deposition modeling three-dimensional printing system. A small-batch production of modeling platforms about 20 pieces can be obtained economically through silicone rubber mold using vacuum casting without applying the plastic injection molding. The air venting systems is crucial for fabricating modeling platform using vacuum casting. Modeling platforms fabricated can be used for building rapid prototyping model after sandblasting. This study offers industrial value because it has both time-effectiveness and cost-effectiveness. [ABSTRACT FROM AUTHOR]

The article offers information on the marginal misfit and microleakage of cement-retained implant-supported crown copings. It mentions that the crown copings have achieved by laser sintering and casting techniques. It also informs that single crown structures have developed with the help of laser-sintered Cobalt-Chromium (Co-Cr), vacuum-cast Co-Cr (CC) and vacuum-cast Nickel-Cr-Titanium.

The need to develop products with special characteristics and high mechanical properties led to the introduction of plastic deformation of semifinished materials. Special purpose products are produced from slabs, blooms, billets or from different size ingots. One of the critical conditions to meet quality expectations after plastic deformation is that the material must be as high quality as possible. For refining steels, a range of methods have been developed that can remove harmful elements from the physical and mechanical product properties. For these products, the chosen casting method is one of the most important factors that can ensure product quality because casting can easily remove the beneficial effects of the refining process conducted during the development of the steel melt by contamination with refractory material from the casting assembly, re-oxidation of the metal bath and others. Depending on the complexity of the casting product and to obtain a superior quality product, several methods of casting have been developed. The usual method of casting high quality large ingots is in vacuum, the advantage is that the steel stream is protected from the surrounding atmosphere, this paper aims to highlight the benefits of vacuum casting with wide stream on the improvement of ingot quality by increasing purity and decreasing gas content. [ABSTRACT FROM AUTHOR]

Abstract: A vacuum casting method to replicate shark skin surface accurately in large area was investigated to overcome some difficulties in the replication process. The fresh shark skin was pretreated as a replication sample, and the replication mold of shark skin was manufactured by casting the unsaturated polyester resin under vacuum and laying the multilayer glass fibers. Under vacuum condition, silicone rubber was poured into the resin mold to obtain the replication film of the shark skin with micro-riblets. The contour of the micro-riblet was measured by a Talysurf CLI2000 machine to evaluate the replication accuracy. Based on the contacting angle measurement, the hydrophobic property of the micro-riblet''s surface was investigated. It was found that the vacuum casting method was an effective replication technology which was suitable to form large-area and highly accurate micro-riblets on the surface of the shark skin. The experiment of drag reduction was conducted in a water tank. Based on the experimental results, the replicated film of shark skin played a significant role in reducing drag. The maximum and minimum of drag reduction rate were 18.6% and 9.7%, respectively. [Copyright &y& Elsevier]

Hybrid moulds with mouldings blocks made with epoxy composites are being used in injection mouldings of precision parts. In the last decade developments were made in view of applying these production series of thermoplastics injection mouldings. This paper reviews some of the outcomes of research activity on specific issues of manufacturing and utilisation of these tools. Most of the results refer to moulding blocks produced in epoxy composites that were manufactured using the vacuum casting technique. Some references are also made to rapid tooling techniques based on laser sintering. [ABSTRACT FROM AUTHOR]

A rapid fabrication process was developed by combining stereolithography prototype, silicone rubber mould and vacuum casting process for zinc alloy moulds. Transfer coating mould was introduced as casting moulds reproduced from silicone rubber moulds. Vacuum casting process was applied to improve filling ability of complicated mould with fine pattern surface. Vacuum reduces the gas counterpressure in the casting mould cavity and then improves the filling ability. [ABSTRACT FROM AUTHOR]

Abstract: An innovative dry electroencephalography (EEG) electrode has been successfully designed and tested, in which multiple micro-spike electrodes, each of them consisting of a micro-pillar with a micro-tip on top of it, were designed to pass through the hairs and establish electrical conduction at the skin-electrode interface by penetrate into the stratum corneum of the skin. For hygiene reasons, such electrodes should be made disposable, at the same time, should be cost effective. Therefore, a mass production technology, including the processing methods, such as casting, has to be designed and developed. In this project, the micro-spike dry electrodes were fabricated by a vacuum casting method using a master pattern piece made by CNC micro-machining, in which silicone rubber moulds are created and then used to vacuum cast polyurethane (PU), epoxy or epoxy-carbon micro-spike electrodes. In order to obtain a harder polymeric material, varying amount of carbon fillers were added to the epoxy resin, and the hardness of the resulting material were measured and compared. It was found that a higher concentration of added carbon fillers resulted in a harder cast polymer composite. Further to the vacuum casting, to create an electrically conductive layer on the vacuum-casted electrode, an Ag/AgCl electroless deposition method has been developed. The sputtering of the conductive layer was also carried out for comparison. The developed micro-spike electrodes showed better performance in terms of the impedance level and stability as well as a much higher efficiency in EEG measurement. [Copyright &y& Elsevier]

Micromoulds are generally produced by lithography methods that often use glass and silicon wafer as substrates, with the exception of the Lithographie Galvanoformung Abformung (LIGA) method, which uses metal substrate. These fabricated moulds are then integrated into the injection moulding machine for mass production. This paper presents the use of vacuum casting methods to produce micromoulds instead of lithography. Silicone rubber is used as the mould material, which is capable of achieving nanometre surface finish. The master pattern of 1-mm diameter microgear of 60-μm teeth width and 38-μm thickness was created by standard ultraviolet (UV) lithography using SU8 photoresist. Using the vacuum casting method, ten polyurethane microgear specimens of 1-mm diameter and 38-μm thickness using the silicone rubber micromoulds have been successfully cast under vacuum conditions as a demonstration. Measurement from white-light interferometry (WLI) showed that all of the microgear cavities in the micromoulds were dimensionally accurate and consistent to the master microgear, proving that its repeatability is possible. [ABSTRACT FROM AUTHOR]

Utilisation of functional prototypes during the upstream design stage is able to shorten the product development cycle of a medical device and quicken the transfer process to mass manufacturing. Innovative synergy of conventional manufacturing techniques and rapid prototyping techniques is thus needed to fabricate functional prototypes successfully. This case study reports on the development of an automatically activated safety needle using different prototyping approaches for the fabrication of functional prototypes. The approaches include rapid prototyping, computer numerical control (CNC) machining and vacuum casting. The challenges of each technique are discussed and solutions are presented. A hybrid technique involving CNC machining and vacuum casting is adopted to fabricate the prototypes. This hybrid prototyping approach was able to expand the choices for materials to fabricate the prototypes and thus enabling the validation of the design mechanism in a shorter time. [ABSTRACT FROM AUTHOR]

Abstract: A micro-mould fabrication method based on vacuum casting was developed and its functionality and reproducibility were demonstrated. The micro-components used in this study were SU-8 photoresist micro-gears fabricated by UV photolithography. These micro-gears served as the master patterns from which silicone rubber micro-mould cavities were fabricated with the use of the vacuum casting technology. The process parameters that had an influence on the quality of the micro-mould cavities were identified and optimised. Using the optimised process parameters resulted in high fidelity silicone rubber micro-mould cavities at high resolutions. Dimensional analysis was carried out using white light interferometry. It was found that all the micro-gear cavities in the micro-moulds were dimensionally accurate and consistent to the master gear, with a dimension deviation less than 3% of the respective dimensions. Micro-casting was also carried out using the silicone rubber moulds. Micro-gears were successfully transferred from the silicone rubber moulds into PU resin and wax pieces under vacuum conditions, thereby demonstrating that the micro-mould fabricated was capable of producing functional micro-parts that were able to replicate micro-features. [Copyright &y& Elsevier]

Abstract: The present work concerns the hardware development of a mid-size humanoid robot, Bonobo, focusing on the use of an integrated application of CAD/CAM/CAE and rapid prototyping (RP) for the rapid development of the robot''s outer body parts. Most parts were three-dimensionally designed with 3D CAD, which enables effective connection with CAE analyses, the basis of which lays in kinematic simulation and structural analysis. To reduce the lead time and investment cost of developing parts, RP and CAM are selectively used to manufacture master parts for the body. These master parts are then replicated by using a vacuum casting process, from which we can repeatedly obtain plastic parts. Through this integrated approach, we successfully developed a prototype of Bonobo with a relatively low time and investment cost. [Copyright &y& Elsevier]

Stereolithography and vacuum casting are two well-established techniques for producing complex parts for rapid prototyping purposes. Although they have been used across a wide range of industrial sectors, parts fabricated by those techniques exhibit weak mechanical properties hindering thus their further application as functional prototypes under loading conditions. This paper investigates the effects of the addition of nonwoven glass fibre mats, and of various thicknesses, on the mechanical properties of laser solidified and vacuum moulded specimens. The test specimens were fabricated using an epoxy-based photopolymer for the stereolithography and a polyurethane resin for the vacuum casting process, correspondingly. Embedment/bonding issues of the reinforcing mats are discussed, while comparisons of the mechanical properties between nonreinforced and their fibre mat reinforced counterparts are also presented. Experimental results show that fibre mat addition yields higher measured tensile properties, with the most pronounced improvements obtained for the reinforced polyurethane specimens. [Copyright &y& Elsevier]

Porous materials are widely employed in a wide variety of industrial applications due to their advanced functional performance. Porous aluminum is among the most attractive metallic materials. It can be produced using repeatable methods involving a replicated Al foam that also provides porosity control. In this work, a highly porous replicated Al foam was fabricated. First, the model of multifunctional packing density was used and corrected to select the appropriate space holders. Then, Al foam was produced using a double-granular sodium chloride space holder. The obtained results showed a maximum porosity of 65% that was achieved using a mix of coarse, irregular granules with spherical granules of intermediate size. [ABSTRACT FROM AUTHOR]

Sample preparation is an important step when testing the mechanical properties of materials. Especially, when carbon nanotubes (CNT) are added to epoxy resin, the increase in viscosity complicates the casting of testing specimens. We present a vacuum casting approach for different geometries in order to produce specimens from functional nanocomposites that consist of epoxy matrix and oxidized multi-walled carbon nanotubes (MWCNTs). The nanocomposites were characterized with various mechanical tests that showed improved fracture toughness, bending and tensile properties performance by addition of oxidized MWCNTs. Strengthening mechanisms were analyzed by SEM images of fracture surfaces and in-situ imaging by digital image correlation (DIC). [ABSTRACT FROM AUTHOR]