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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]

Background/aims: Mouthguards can reduce the risk of sports-related injuries but the sheet material and thickness have a large effect on their efficacy and safety. The aim of this study was to investigate the effect of the thermoforming technique that moves the model position just before vacuum formation.Materials and Methods: Ethylene vinyl acetate sheets of 4.0-mm thickness and a vacuum forming machine were used. The working model was placed with its anterior rim positioned 40 mm from the front of the forming table. Three forming conditions were compared: (a) The sheet was formed when it sagged 15 mm at the top of the post under normal conditions (control); (b) the sheet frame was lowered to and heated at 50 mm from the level of ordinary use, and the sheet was formed when it sagged 15 mm (LH); and (c) the sheet frame at the top of the post was lowered and covered on the model when it sagged 15 mm. Subsequently, the rear side of the model was pushed to move it forward 20 mm, and it was then formed (MP). Sheet thickness after fabrication was determined for the incisal edge, labial surface, and buccal surface using a specialized caliper accurate to 0.1 mm. Thickness differences among forming conditions were analyzed by one-way ANOVA and Bonferroni's multiple comparison tests.Results: A significant difference was observed for all measurement points, and the thickness after formation increased in the order of control, LH, and MP. Particularly on the labial surface, MP was able to yield about 1.7 times the thickness (about 3.1 mm) of the control.Conclusion: The forming method of moving the model forward just before vacuum formation was effective for suppressing the mouthguard thickness reduction, which is capable of securing the labial thickness at 3 mm or more with a single layer. [ABSTRACT FROM AUTHOR]

A modified vacuum infusion (VI) process, which we refer to as the progressive compression method (PCM), has been proposed to reduce the filling process. In PCM, the bag is divided into several segments. During infusion, all segmented bags are pulled upward by the vacuum. Resin is easily infused into the loose preform. Once enough volume of resin is infused, the vacuum on the segmented bags is released in a step-wise manner. The atmospheric pressure is progressively applied on the segmented bags that are inflated to squeeze the surplus resin from the wetted preform through the dry preform. The flow enhancement is achieved since the dry preform remains loose during the filling process. Once the preform is fully saturated, the post-filling stage is performed for achieving the uniform thickness of the part. In the present study, seven cases is utilized to investigate the effect of three key process variables, including the number of the compression segment, initiating timing of the next segmented compression and volume of infused resin, on the complete filling process. Numerical results show that the multi-segment compression and appropriately premature initiation of the next segmented compression can reduce the filling process; whereas, the excess infused resin can significantly increase the total filling time due to the very slow post-filling stage. Compared with the traditional VI process, PCM at the optimal case reduces the filling time by 10.15% with the same resin consumption as VI. [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]

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]

Cu9Al4Fe/1Cr18Ni9Ti stainless steel bimetallic composite was prepared by the method of vacuum casting. The microstructure morphology, mechanism bonding and mechanical property of Cu9Al4Fe/1Cr18Ni9Ti bimetallic composite were observed by scanning electron microscope, energy disperse spectroscopy, X-ray diffraction, transmission electron microscope and nano-indentation analysis techniques respectively. The research results are as follows: The interface transition layer of Cu9Al4Fe/1Cr18Ni9Ti bimetallic composite maintains straight and a certain thickness and no obvious defects are observed. The phase on the transition zone is consisted of α-Fe based solid solution, γ-Fe based solid solution, NiAl phase and AlCr 2 phase. The micro-hardness and elastic modulus of the interface transition layer are higher than the two matrix alloys. The fracture of Cu9Al4Fe/1Cr18Ni9Ti bimetallic composite prefers to occur between 1Cr18Ni9Ti and the interface transition layer, and the fracture mode is cleavage fracture. [ABSTRACT FROM AUTHOR]

Shortening the time-to-market is an important issue in the manufacturing industry. Indirect tooling technology was regarded as a promising approach of reducing time and cost to the market in a new product development phase. Silicone rubber mold was frequently employed in the indirect tooling. In this study, the service life of silicone rubber molds was investigated using both wax injection molding and vacuum casting. The experimental results revealed that the average roughness of the inner surface of silicone rubber mold were increased with increasing the number of test runs and saturated after 25 test runs. The degassing time needs to be increased with increasing the number of test runs in the vacuum casting process. The criteria for judging the service life of silicone rubber molds include surface quality of the parts fabricated, whitening regions in the inner wall surfaces of silicone rubber molds, and the overall elasticity of silicone rubber molds. [ABSTRACT FROM AUTHOR]

In the low cost application of vacuum casting in rapid prototyping, a mould cavity with high modulus is necessary for producing plastics parts in small quantity. In this work, a silicone matrix was reinforced with natural fibers to improve the modulus of composites to mould and to reduce the cost of silicone materials. Sisal fiber with different compositions was reinforced with silicone in a compression moulding process. Mechanical properties were studied. An increase in tensile strength, tear strength, and better hardness was observed in sisal fiber composites. The silane-treated fiber improved the adhesion between fiber and matrix and enhanced the mechanical properties of the composites. The swelling method was adopted to determine the crosslinking density of composites through the Flory-Rehner equation. The flexibility of silicone composites decreased for higher fiber loading and there was an increase in cross-linking of the fiber network to improve modulus of the composites. A morphological study was conducted using X-ray tomography and scanning electron microscopy (SEM) to predict the defects, orientation, debonding, fractography, and interfacial adhesion of fiber/matrix composites. [ABSTRACT FROM AUTHOR]

QAl9-4 aluminum bronze and 304 stainless steel composites were fabricated by vacuum smelting-casting at 1150 °C, in a vacuum of 4.0 × 10 −2 Pa. Microstructure and chemical composition were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). Properties of interface were studied by shear tests and hardness measurement. Between the QAl9-4 aluminum bronze and 304 stainless steel, a transition zone that the width is about 133 μm and the maximum micro-hardness value is 467 HV was observed. It is much higher than that of QAl9-4 aluminum bronze and 304 stainless steel, the main reason is considered to the formation of the brittle intermetallic compounds such as AlCrFe 2 , Al 4 Cu 9 and AlNi 3 , but these intermetallic compounds are very easy to cause the interfacial fracture. The interfacial shape close to 304 stainless steel is flat, but to QAl9-4 aluminum bronze is zigzag. The shear strength of the composite is 278 MPa. Microstructure formation mechanism of interfacial layer can be mainly considered as Fe, Cr atoms of steel substrate are given a priority in molten copper liquid compared with impurity elements (Mn, Si), eventually forming a good metallurgical bonding state on both sides of the substrate through inter-diffusion of interfacial atoms. [ABSTRACT FROM AUTHOR]

Copyright of FME Transactions is the property of University of Belgrade, Faculty of Mechanical Engineering 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.)

Background: Unevenness in softening of the plastic sheet leads to a decrease in the mouthguard thickness during thermoforming. In this study, we examined the heating methods for reducing unevenness when softening mouthguard sheets during vacuum-pressure formation.Materials and Methods: Ethylene vinyl acetate mouthguard sheets and olefin copolymer sheets (thickness: 4.0 mm) were used. The following three heating conditions were compared: condition A-the sheet was molded when it sagged 15 mm from the sheet frame (under normal condition); condition B-the heater was turned off when the sheet sagged by 10 mm from the frame, followed by the sheet molding when the sagging reached 15 mm below the frame; and condition C-the sheet was inverted after heating when the sheet sagged 10 mm and was molded when the sagging reached 15 mm below the frame. The sheet was heated and pressed over the model using a vacuum-pressure machine; then, 10 s of vacuum forming and 2 min of pressure molding were applied. The sheet temperatures were measured using a radiation thermometer. Thickness of the fabricated sheets was determined for the incisal and the molar portion using a measuring device. Thickness data for each condition were analyzed by one-way anova followed by Bonferroni's multiple comparison tests.Results: On both sheets, condition B was smallest for temperature difference between the heated and the non-heated surface, and thicknesses after molding were greatest at all measuring portions.Conclusion: By comparing changes in sheet temperatures at molding and variation in thicknesses when applying the heating method using a vacuum-pressure molding machine, we found that reduced unevenness in sheet softening occurred when the heater was turned off when the sag distance of the sheet was 5 mm less than the conventional molding, and then, the sheet was pressed when the conventional sag distance was reached. [ABSTRACT FROM AUTHOR]

Aim: The purpose of this study was to examine the differences of the vacuum-formed mouthguard thickness by the timing of vacuum application.Materials and Methods: The material used in this study was a mouthguard sheet of 3.8-mm ethylene vinyl acetate. Three conditions of the timing of vacuum application were examined: the vacuum was applied immediately, 5 s after, and 10 s after the sheet holder was lowered over the vacuum-forming stand. We measured mouthguard thickness at the labial surface of the central incisor, buccal surface of the first molar, and occlusal surface of the first molar. Differences in thickness in different regions of mouthguards formed under different timing of vacuum application were analyzed by two-way analysis of variance and Bonferroni method.Results: We found that mouthguard thickness differed in different regions of the central incisors and the first molars (P < 0.01). The mouthguard thickness at the labial surface of the central incisor and buccal surface of the first molar became thinner when the vacuum was applied immediately after the sheet holder was lowered over the forming stand. The thickness at the occlusal surface of the first molar did not vary with the timing of vacuum application.Conclusions: Our results suggest that the thicknesses of the labial surface of the central incisor and buccal surface of the first molar became larger when the vacuum was applied several seconds after the sheet holder was lowered over the forming stand. This finding is necessary knowledge when forming a mouthguard sheet. [ABSTRACT FROM AUTHOR]

Background: The goal of the present study was to examine the thickness of mouthguards molded under a variety of heating conditions to clarify suitable conditions during vacuum-pressure forming of ethylene vinyl acetate sheets.Materials and Methods: Mouthguards were fabricated using ethylene vinyl acetate (EVA) sheets (thickness: 4.0 mm) using a vacuum-pressure forming machine. The sheet was pressed against the working model, followed by vacuum forming for 10 s and compression molding for 2 min. Three heating conditions were investigated in which the sheet was molded when the center of the softened sheet sagged 10 mm, 15 mm, or 20 mm below the clamp (H-10, H-15, or H-20 respectively). The temperature of the sheet surface was measured using a radiation thermometer under each heating condition. The thickness of the mouthguard sheets after fabrication was determined for the incisal portion (incisal edge and labial surface) and molar portion (cusp and buccal surface), and dimensional measurements were obtained using a measuring device. Differences in thickness due to the heating condition of the sheets were analyzed by one-way analysis of variance and Bonferroni's multiple comparison tests.Results: The temperature difference between the heated and non-heated surfaces was lowest under H-15. The thickness differences at incisal edge, labial surface, and cusp were determined. The thicknesses for H-10 and H-15 were greater than that for H-20, and the thicknesses for H-10 and H-15 were equivalent at all measurement points. No differences in thickness at the buccal surface were observed for the various heating conditions.Conclusion: The present study demonstrated that a sagging distance of 15 mm provided the most suitable forming process. The results of the present study provide a standard heating condition for EVA sheet forming. [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]

This paper has described an indirect method of rapid tooling technique, using for made the mould to manufacturing a representative part with complex geometry shape, by injection. The different changes in the market requirements entail the necessity of a flexible and efficient manufacturing process. The flexible moulds are made of low - hardness materials, such as silicone rubber, epoxy resin, low - melting point alloys etc., using new techniques like Vacuum Casting and Metal Spraying. The metal spraying techniques is one of the most common procedures used in flexible tools manufacturing. The mould manufacturing by metal spraying was made in the laboratory of Innovative Technologies, at Technical University of Cluj-Napoca, as result of the theoretical and experimental research work of the author, in the framework of doctoral studies in the field of industrial engineering. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate vacuum forming techniques for reduction of loss in mouthguard thickness effects of sheet grooving and thermal shrinkage of extruded sheets on molded mouthguard thickness. Mouthguards were fabricated with ethylene vinyl acetate ( EVA) sheets (4.0 mm thick) using a vacuum forming machine. Sheet form was a convexing v-shaped groove toward the back, 10-40 mm from the anterior end. The sheets were placed in the forming machine with the sheet extrusion direction either vertical or parallel to the model's centerline of right and left. Molding was performed by crimping the sheet using suction when the most descending portion of the sheet sagged downwards from the clamp, 15 mm below the basal surface. Postmolding thickness was determined using a measuring device. Measurement points were the incisal portion (incisal edge and labial surface) and molar portion (cusp and buccal surface). Differences in molded mouthguard thickness with the sheet orientation of extruded EVA sheets were analyzed by student's t-test. The sheet in parallel axis orientation with the model's centerline yielded higher thickness than vertical orientation at the labial surface and the buccal surface. The present results suggested that addition of a groove to the sheet in conjunction with placement of the sheet with its axis of orientation parallel the centerline of the working model can effectively reduce thickness loss in the molded mouthguard with the equipment and materials used in this study. [ABSTRACT FROM AUTHOR]

Purpose - The purpose of this paper is to report on the use of a combination of selective laser sintering (SLS) and vacuum casting to create plastic composites made by additive manufacturing. Design/methodology/approach - The research has been carried out by approaching a new concept of the final part consistent in a plastic component, where the main body is made by SLS and the internal long fibres for reinforcing are made by vacuum casting of high-resistance epoxy resin. The part is designed for optimal number and distribution of the internal fibres taking into account the target relative stiffness (N/mm*kg). The methodology is applied to a pedal clutch of a car which has been tested in an equipment for fatigue and durability, being compared to the correspondent design for injection moulding. Findings - Research has proven that the approach introduces relevant improvement in mechanical properties of the base resin consistent in PA 3200GF (EOS), reinforced by internal long fibres of resin VG SP5. Experiments showed significant increase of stiffness in the pedal clutch made under this procedure, where the stiffness was 77 per cent higher than the conventional SLS part and only 11.7 per cent lower than the one made by injection moulding of PA 66 with 50 per cent fibreglass. Originality/value - The developed method introduces an alternative procedure for increasing the mechanical properties of plastic parts developed in SLS. Optimal orientation and distribution of long fibres clearly achieves better mechanical properties at low cost. [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]

We present an in-depth investigation of contaminated silicone molds by use of scanning electron microscopy, that provides additional insight into the aging process of the molds. The molds lifetime in vacuum casting processes of polyurethane is limited due to contamination with the diisocyanate compound of the PUR resin. SEM investigations, combined with FIB cross-sections and EDX measurements show that three different types of particles are distributed in the contaminated silicone matrix. The particles differ in shape and size, with a range from 50 nm to 50 µm. This explains the loss in transparency and the hardened haptics of contaminated molds. [ABSTRACT FROM AUTHOR]

Casting process is not a common method in producing oxide dispersion strengthened (ODS) alloys due to its difficulty in distributing the oxides in matrix, especially for nano-scale oxide particles. In this paper, 9Cr steel strengthened by micro-scale 0.4 wt% Y 2 O 3 was fabricated through vacuum casting technology containing electromagnetic stirring. Microstructural observation and energy dispersive spectrometry (EDS) analysis of the particles from tensile fracture dimples and extraction by dissolving metal elements, demonstrated that complicated oxides, several microns in diameter, containing elemental Y and O formed and evenly distributed in the steel matrix. The tensile strength was also improved after Y 2 O 3 addition for the steels in both forged and heat treated states, the alloy matrix strengthened was due to the complicated oxides with Y element played a role as obstacles to dislocation gliding. The research confirmed that micro-scale Y 2 O 3 was effectively added to the steel matrix during casting, which provided an alternative method for ODS alloy fabrication. [ABSTRACT FROM AUTHOR]

In this work we present a new method to enhance the durability of silicone molds, which are used in industrial processes for small batch production. The goal is to reduce the aging effects of the molds that occur after a minor number of casting processes and therefore get a higher output of these molds. First the source of the aging effects is identified. It is shown that the molds are nourished with the low molecular components of the polyurethane mixtures during the casting process, and that the diisocyanate component is responsible for the aging effects. For the removal of these components, several solvents are used. Acetone is shown to be most effective; the regeneration leads to a 30% higher output. Because acetone also removed free silicone oil from the molds, a mixture of the solvent with new silicone oil as regenerating agent was applied, which led to an overall improvement of lifetime of 60%. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute 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.)

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 paper provides an analysis of experimental research and results of investment casting process. Temperature field in a ceramic mold is one of the problems during numerical simulation. Reducing the costs of production in precision casting involves the reduction of scraps, which is one of the fundamental problems of the foundry industry. Reducing these costs is associated with optimization of precision casting technology of aircraft engines critical parts, including control of the solidification front in thin-walled castings of nickel super alloys cast in a vacuum. It is achieved by changing the geometrical characteristics of the ceramic mold. The results of the tests were used to optimize the industrial production of aircraft components in Precision Foundry of WSK Rzeszów. Temperature distribution gained in the conducted tests allowed verification and optimization of computer simulations. [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]

In this study, damping ratios of 3 samples made of aluminum foam material, which have different-density pores, were calculated, the effects pore density on damping were examined. Experimental modal analysis method was used for examining of the effects of the pore density on damping. In experimental modal analysis method, frequency charts were obtained by driving to the sample with a hammer. Through these frequency charts, damping ratios of each 3 samples were calculated with ME'scope VES program. It was observed in calculated damping ratios that pore density has influences on damping; thus, damping accordingly increases as the number of pores increases. It is seen that critical damping constant decreases as the material structure changes in terms of volume and density. [ABSTRACT FROM AUTHOR]

To manufacture metal parts with complex shapes through Investment Casting (IC) process using wax models, it is necessary to have a complete control over the entire process. A very important aspect is to know the shrinkage value of the wax models. If the master model has a very small scratch or imperfection, this will appear also on the metal part surface. The structure and the mechanical properties of the metal part can be influenced by material porosity which can appear during the casting process. A given set of parameters such as preheating temperature, casting temperature, turbo pressure applied to finish the casting and also the wall thickness contributes to obtain a good surface quality and to material density which influences the part functionality. The objective of this research is to understand the utility of Vacuum Casting (VC) technology comparing with other casting technologies regarding the part surfaces quality. [ABSTRACT FROM AUTHOR]

The purpose of this article is to present theoretical and experimental researches for optimizing the vacuum casting (VC) process. Due to the phenomenon's that occur during the entire technology, investment casting (IC) proves to be a difficult process to model and analyze. Metal vacuum casting compared to other casting technologies, is considered to be one of the most precise casting processes, regarding the shape and dimensions of the cast parts. Determining the wax pattern dimensions is the first and most important in the investment casting process; it is critical for obtaining metal cast parts with accurate dimensions. To obtain accurate parts it is necessary to increase the dimensions of the master model by adjusting the nominal casting dimensions by the shrinkage factor and also adjusting the feeding system according to the part geometry. [ABSTRACT FROM AUTHOR]

The paper presents the needs and importance to develop new software tools, in order to guide the engineers and assist them for a quick design of the gating system and to estimate the required quantities of materials, within the investment casting process. The existing software packages are discussed and new dedicated software called P-Cast was developed, in order to bring new important features, which are useful to sort out some tasks in rapid metal casting. Some important parameters which are automated calculated by the P-Cast software are: dimensions of the master model and wax parts, envelope size and materials quantities for SRP, was, plaster and metal, solidification time, etc. All these are depending onto the respective part, which is going to be made by vacuum casting. The structure of the new P-Cast software tool is presented and a case study application is presented, illustrated and discussed. [ABSTRACT FROM AUTHOR]

In this paper an innovative method has been proposed of mathematical modeling of aluminum vacuum casting (VC) process. The vacuum casting process use wax patterns with with complex surfaces and fine details In the first part a method is proposed to solve one of the most important problems encountered in the wax casting process and that is the mathematical modeling of the process. Starting from the mathematical modeling for prediction of the wax patterns shrinkage and taking into account the aluminum shrinkage coefficient, a mathematical model has been developed to predict the shrinkage coefficient of the aluminum parts obtained through vacuum casting process. It is necessary to increase the dimensions of the master model by adjusting the nominal casting dimensions with the shrinkage factor. In this way we can manufacture parts at a good dimensional accuracy and surface quality. [ABSTRACT FROM AUTHOR]

The loss of all or part of a finger following traumatic amputation may have a negative impact on physical and psychological well being. An esthetic prosthesis can offer psychological, functional, and rehabilitative advantages. The success of a prosthetic restoration primarily depends on its retention. This clinical report describes an alternative method of retention by scoring the master cast of a partially amputated finger, thus enhancing the vacuum effect for the retention of the prosthesis. The methodology of treatment is also explained. Silicone material was used to provide function and esthetics. [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]