Metal Mold Research Articles

An Experiment on Surface Fluctuation of Ga-In-Sn Alloy with a Permanent Magnet Flow Control Mold

To control well the surface fluctuation of liquid metal in a slab mold, a new type of combined permanent magnets braking system, namely a permanent magnet flow control mold (PMFC-Mold) is proposed by our research group, of which its main feature is that the device can control the flow of molten steel in the mold without additional energy. To observe the fluctuation state of the alloy with the PMFC-Mold, instantaneous surface fluctuations were recorded by a laser level meter and camera. To study the effect of various casting speeds and permanent magnet placement on surface fluctuations, the three measurement points, which were 7, 18, and 36 mm away from the narrow surface of the mold, were selected to record the trend of level fluctuation. Three types of permanent magnet placement were designed by setting the differences between the height center of the permanent magnet and the free surface in the slab mold, which were H1 = 0 mm, H2 = −25 mm, and H3 = −75 mm. The experimental results indicated that with the acceleration of the casting speed, the average height and standard deviation of surface fluctuation at the measurement point increased, but the surface fluctuation pattern remained. When the permanent magnets were arranged at H1 = 0 mm and H2 = −25 mm, the position of the magnetic field was reasonable and the surface fluctuation could be effectively suppressed. In contrast, when the permanent magnets were arranged at H3 = −75 mm, the level fluctuation was intensified.

Meta‐analysis of thermal contact resistance in injection molding: A comprehensive literature review and multivariate modeling

AbstractThis article provides the first multivariate analysis of reported thermal contact resistance (TCR) values from different characterization approaches (injection and compression molding) having missing data. The missing data are estimated by principal components analysis (PCA) with alternating least squares (ALS), and then the main effects are modeled using multiple regressions. Three models of increasing complexity are presented, each of which provides reasonable model fidelity relative to the TCR values reported in the literature. The primary cause of differences between reported TCR values as characterized by injection molding and compression molding can be explained by the melting of the polymer to make intimate contact with the metal mold during processing. Typical values of TCR are on the order of 0.0002 m2K/W, corresponding to heat transfer coefficients of 5000 W/(m2K). The analyses suggest that the TCR decreases significantly with increasing processing temperature and pressure but increases most significantly during cooling with the development of an air gap between the polymer and mold. Accordingly, it is strongly recommended that injection molding simulations incorporate modeling of the TCR as a function of the processing states for accurate prediction of the air gap, residual stresses, shrinkage, and warpage.Highlights Multivariate analysis of thermal contact resistance data from the literature. Sparse data handled by principal component analysis and alternating least square. Comparison of injection molding and compression molding measurements. Results suggest thermal contact resistance should be modeled as a function of the processing states.

In vitro comparative assessment of the denture cleansers effectiveness on the surface hardness of permanent silicone denture line

The purpose of the current research was to evaluate the impact of various denture cleaners on the surface hardness of permanent silicone denture lines. In the present study, 124 specimens were included comprising of soft liners made of permanent silicone, which were made from the 15 mm x 10 mm custom metal mold dimensions, where 62 samples were made of Molossil™ and 62 other of Voco™ which are commercially available liners for permanent dentures. These samples were then divided into 4 groups of equal specimen numbers (n=32) depending on the cleansing treatments. Group I specimens were cleaned with water daily, and Group II Polident™ Group III was given SecureTM denture cleaning solution, while Group IV was given PeriogardTM denture cleaning solution. The samples were assessed at 1st week, 1st month, and 6th month after cleanser use. The study results showed that at the 6th-month follow-up after the use of denture cleansers, all of the samples had considerably increased surface hardness compared to the baseline. Statistically significant results were seen with Periogard™, Secure™, and Polident™ compared to Group I controls. In Voco™ denture liners, minor changes were seen compared to Molossil™ soft liners with time in all the groups. The results of this investigation are significantly well cleansing action is seen with Voco™ soft denture lining material compared to Mollosil™ soft denture lining material, and surface hardness is least affected by Polident™ denture cleanser compared to Secure™ and Periogard™ denture cleansing agents.

Microstructural and mechanical characteristics of AlSi5Cu3 aluminum alloy cast in metal mold and sand mold

In this effort, the impact of mold material on the microscopic behavior and mechanical performance of AlSi5Cu3 alloy was investigated. The AlSi5Cu3 alloy was cast in the metal and sand molds with equal cavity size and the characteristics of castings were evaluated. The metallographic analysis revealed that, due to the rapid solidification, the number of grains is 2.17% higher and the grain area is 3.71% less compared to sand mold casting. Moreover, due to the formation of more refined grain structures, metal mold casting has greater mechanical properties compared to sand mold casting. The findings revealed that the hardness, ultimate tensile strength (UTS), and impact strength of metal mold casting samples were improved by 8.82%, 10.74%, and 12.5% compared to sand mold casting samples.

Influence of melt temperature on microstructural characteristics and mechanical properties of AlSi5Cu3 aluminum alloy

In this work, the impact of melt temperature on the microscopic and mechanical characteristics of AlSi5Cu3 alloy was studied. The AlSi5Cu3 alloy was individually melted at 750 °C, 800 °C, and 850 °C followed by pouring into the metal mold, and the characteristics of castings were evaluated. The results revealed that, due to a higher cooling rate in 750 °C melt temperature, the secondary dendrite arm spacing (SDAS) was reduced by 8.58% and 20.40% while the grain size was decreased by 5.35% and 9.18% compared to 800 °C and 850 °C respectively, indicating formation refined grain structure. Moreover, due to grain refinement, the castings developed at 750 °C melt temperature possessed maximum mechanical properties followed by 800 °C and 850 °C. For 750 °C melt temperature, the ultimate tensile strength (UTS) was improved by 3.78% and 7.03%, whereas, the hardness was increased by 5.40% and 14.70% compared to 800 °C and 850 °C respectively. Overall, the grain refinement and mechanical performance were improved by lowering the melt temperature.

High-Resolution Nanotransfer Printing of Porous Crossbar Array Using Patterned Metal Molds by Extreme-Pressure Imprint Lithography.

High-resolution nanotransfer printing (nTP) technologies have attracted a tremendous amount of attention due to their excellent patternability, high productivity, and cost-effectiveness. However, there is still a need to develop low-cost mold manufacturing methods, because most nTP techniques generally require the use of patterned molds fabricated by high-cost lithography technology. Here, we introduce a novel nTP strategy that uses imprinted metal molds to serve as an alternative to a Si stamp in the transfer printing process. We present a method by which to fabricate rigid surface-patterned metallic molds (Zn, Al, and Ni) based on the process of direct extreme-pressure imprint lithography (EPIL). We also demonstrate the nanoscale pattern formation of functional materials, in this case Au, TiO2, and GST, onto diverse surfaces of SiO2/Si, polished metal, and slippery glass by the versatile nTP method using the imprinted metallic molds with nanopatterns. Furthermore, we show the patterning results of nanoporous crossbar arrays on colorless polyimide (CPI) by a repeated nTP process. We expect that this combined nanopatterning method of EPIL and nTP processes will be extendable to the fabrication of various nanodevices with complex circuits based on micro/nanostructures.

Application of the NSGA-II Algorithm and Kriging Model to Optimise the Process Parameters for the Improvement of the Quality of Fresnel Lenses.

The Fresnel lens is an optical system consisting of a series of concentric diamond grooves. One surface of the lens is smooth, while the other is engraved with concentric circles of increasing size. Optical interference, diffraction, and sensitivity to the angle of incidence are used to design the microstructure on the lens surface. The imaging of the optical surface depends on its curvature. By reducing the thickness of the lens, light can still be focused at the same focal point as with a thicker lens. Previously, lenses, including Fresnel lenses, were made of glass due to material limitations. However, the traditional grinding and polishing methods for making Fresnel lenses were not only time-consuming, but also labour-intensive. As a result, costs were high. Later, a thermal pressing process using metal moulds was invented. However, the high surface tension of glass caused some detailed parts to be deformed during the pressing process, resulting in unsatisfactory Fresnel lens performance. In addition, the complex manufacturing process and unstable processing accuracy hindered mass production. This resulted in high prices and limited applications for Fresnel lenses. These factors prevented the widespread use of early Fresnel lenses. In contrast, polymer materials offer advantages, such as low density, light weight, high strength-to-weight ratios, and corrosion resistance. They are also cost effective and available in a wide range of grades. Polymer materials have gradually replaced optical glass and other materials in the manufacture of micro-optical lenses and other miniaturised devices. Therefore, this study focuses on investigating the manufacturing parameters of Fresnel lenses in the injection moulding process. We compare the quality of products obtained by two-stage injection moulding, injection compression moulding, and IMD (in-mould decoration) techniques. The results show that the optimal method is IMD, which reduces the nodal displacement on the Fresnel lens surface and improves the transmission performance. To achieve this, we first establish a Kriging model to correlate the process parameters with optimisation objectives, mapping the design parameters and optimisation objectives. Based on the Kriging model, we integrate the NSGA-II algorithm with the predictive model to obtain the Pareto optimal solutions. By analysing the Pareto frontier, we identify the best process parameters. Finally, it is determined that the average nodal displacement on the Fresnel surface is 0.393 mm, at a holding pressure of 320.35 MPa and a melt temperature of 251.40 °C. Combined with IMD technology, product testing shows a transmittance of 95.43% and an optimisation rate of 59.64%.

Thick film MEMS process using reverse lift-off

The lift-off process is a microfabrication technique that has the capability of forming thin film structures. However, several issues, such as structural shape and burr formation, arise when applying this method to the formation of thick film structures. Thick film structures formed through the lift-off process exhibit a mountainous cross-sectional shape and non-uniform film thickness due to variations in the width of the structure. These challenges make it difficult to apply the method to MEMS. While the reverse lift-off process addresses some of the structural shape problems, its initial development using metal molds makes it challenging to directly apply to MEMS without modification. Therefore, this paper proposes an adaptation to the Si process and presents a method to reduce burrs. The microfabrication characteristics are evaluated by comparing the cross-sectional shapes of thick metallic glass structures formed through both the lift-off and reverse lift-off processes. The structures formed through the reverse lift-off process exhibit a rectangular cross-sectional shape, and the film thickness remains consistent regardless of the structure's width. However, burrs persist on the backside edge of the structure, which hinders its application to MEMS. This paper confirms that pre-etching the underlying Si substrate into an inverse tapered shape effectively reduces burrs. As an illustration of the improved reverse lift-off process applied to MEMS, MEMS mirror structures are fabricated, and their resonance frequency closely aligns with the design value.

RESTORATION OF METAL MOLDS FOR CENTRIFUGAL CASTING OF PIPE FROM HIGH-STRENGTH IRON BY ARC WELDING

Currently, metal molds for casting cast-iron pipes operate under severe temperature and deformation conditions, as a result of which they fail due to wear of their inner surface and the formation of cracks and a mesh of heat in the same place. (Research purpose) The research purpose is studying the possibility of defect-free restorative surfacing of the inner surface of metal molds without preheating in the environment of protective gases. (Materials and methods) All work on the development of the metalform surfacing technology was carried out on samples cut from the original metalforms. The method of arc surfacing in the environment of protective gases was taken as a basis. Various welding wires and protective media were tested for surfacing. Assessment of the surfacing quality for the presence of pores and cracks before and after mechanical treatment was carried out visually, followed by determination of the chemical composition and hardness of the deposited layer. (Results and discussion) Surfacing was carried out on the inner surfaces of the samples without preheating them. Various wires were tested for surfacing: Sv-18XGS, Sv-18XM and Np-30XGSA based on obtaining a composition close to the composition of the base metal in the deposited layer. As a result, Sv-18XMA welding wire with a diameter of 2.0 millimeters was chosen for the restorative surfacing, and a welding mixture was used as a protective medium, ensuring satisfactory formation of the deposited layer without pores and cracks with minimal splashing in the selected modes. Studies were carried out to determine the hardness and chemical composition of the deposited layer and the base metal of metal forms. (Conclusions) Proposed a technology for reducing the surfacing of the inner surface of metal molds without preheating. A comparative analysis of the hardness and chemical composition of the deposited layer and the base metal of the metal forms showed a comparable level of hardness and alloying elements in them, which will ensure the necessary wear and heat resistance of the restored metal forms

Surface Analysis of a Universal Resin Composite and Effect of Preheating on its Physicochemical Properties.

This study was aimed at analyzing the surface properties of a universal resin composite and evaluating the effect of preheating on its physicochemical properties. Two commercial resin composites were used under two conditions: Filtek Universal Restorative (UR); UR preheated (URH); Filtek Supreme (FS) and FS preheated (FSH). The film thickness (FT) test (n = 10) was done using two glass slabs under compression. Flexural strength (FLS) and modulus (FLM) were evaluated using a three-point flexion test (n = 10). Polymerization shrinkage stress (PSS) was evaluated in a universal testing machine (n = 5). Gap width (GW) between composite and mold was measured in internally polished metallic molds (n = 10). The degree of conversion (DC) was evaluated by Fourier Transform Infrared spectroscopy (n = 3). The morphology of the filler particles was checked by scanning electron microscope (SEM) and EDX analysis. Surface gloss (SG) and surface roughness (SR) were evaluated before and after mechanical brushing (n = 10). The outcomes were submitted to 2-way ANOVA and Tukey's test (α = 0.05). Lower mean values of FT were observed for the preheated groups when compared to the non-preheated groups. URH and FSH showed higher mean values of FLS and FLM when compared with UR and FS. No differences were observed between groups in the PSS test. The GW was higher for the UR and FS groups when compared with URH and FSH. The DC was higher for preheated resin composites when compared to the non-preheated groups. The SR of the UR composite was higher than the FS after mechanical brushing, while the SG was higher for the FS groups. In conclusion, the universal resin composite tested generally presented similar physicochemical properties compared with the nanofilled resin composite and either similar or slightly inferior surface properties. The preheating improved or maintained all properties evaluated.

The characteristics of the mechanical and acoustic bronze cu20sn as traditional bell material

This study is aimed to find out the mechanical and acoustic characteristics of casting traditional bell's result using metal mold and sand mold. The mechanical and acoustic characteristics of casting traditional bell's result are compared between metal molded and sand molded casting. The bronze alloy was smelted in a crucible furnace at the casting temperatures of 1000, 1050, and 1100 °C. The melted alloy is poured into a sand mold and a preheated metal mold at a temperature of 200 °C. Specimens were formed into bell and billet. The bell form was for acoustic testing. The Billet casted was cut into a few parts and were manufactured as a specimen for hardness test. This study has showed that mechanical characteristic specifically the hardness of metal molded casting is better than sand molded casting. The Acoustic properties of particular damping characteristicsis depended on the porosity of casting’s result. The bell’s tone isn’t produced by the mono frequency but it’s generated by more than one frequency domain. Similarly, the subjective test of acoustic characteristic didn’t show a significant obvious difference.

Evaluation of Compressive and Flexural Strengths of Two Resin-based Core Materials with an Alkasite Material: An In Vitro Study.

To compare and evaluate the compressive and flexural strengths of two resin-based core build-up materials with an alkasite material. ParaCore, Tetric N ceram Bulk-fill composite, and Cention N were used. A total of 90 specimens were prepared. Customized cylindrical split molds of dimension 6 ± 1 mm (height) × 4 ± 1 mm (diameter) were used to fabricate 15 samples of each core material for testing the compressive strength and rectangular split metal molds of dimensions 25 ± 1 mm (length) × 2 ± 1 mm (width) × 2 ± 1 mm (height) were used to fabricate 15 samples of each core material for testing the flexural strength. Then the samples were tested using a Universal testing machine (UTM). The compressive and flexural strengths of Cention N were significantly less than ParaCore® but higher than Tetric® N-CeramTM Bulk-fill core build-up material. Within the limitations of this study, it was concluded that Cention N may be used as an alternative to other core build-up materials after further in-vitro and in-vivo studies. Cention N had the added advantage that self-cure polymerization alone was sufficient to achieve good physical properties when compared to the other two resin-based core build-up materials.

Comparative Study on Metallography and Mechanical Properties of Al–Cu–Ni/FeNb Composites Fabricated by Electromagnetic Stir Casting Processes via Sand and Metal Mold System

Comparative Study on Metallography and Mechanical Properties of Al–Cu–Ni/FeNb Composites Fabricated by Electromagnetic Stir Casting Processes via Sand and Metal Mold System

Research on the Heating Process of CFRP Circular Tubes Based on Electromagnetic Induction Heating Method.

Based on the electromagnetic induction heating method, heating and curing of Carbon Fiber Reinforced Polymer (CFRP) have the advantages of high energy utilization and no pollution. However, in the heating process, both the material weaving structure and mold material can affect the temperature field. Therefore, in this study, an electromagnetic heating finite element analysis model for CFRP circular tubes was established based on the equivalent electromagnetic thermal characteristics of CFRP. The study investigated the temperature rise mechanism of the material weaving structure under the magnetic field, and explored in-depth the influence of molds made of 45# steel and glass fiber-reinforced plastic (FRP) on the heating process of CFRP. The CFRP circular tubes with weaving structures of 89-degree winding angle, 45-degree winding angle, and plain weave were studied. The study found that when the metal mold was heated, the CFRP structure had almost no effect on the temperature distribution. However, when the glass fiber-reinforced plastic mold was heated, the temperature field changed with the CFRP structure, and the more fiber cross points, the more uniform the temperature field. The accuracy of the finite element model was verified through experiments. The aim of this research is to provide theoretical guidance for actual industrial production.

Evaluation of the Effect of Two Surface Treatment Methods on Shear Bond Strength between Porcelain Veneer and Two Different Zirconia Blocks

Introduction: The aim of the study was to test the effect of two surface treatment methods on shear bond strength between a porcelain veneer and two different zirconia blocks. Materials and Methods: Sixty disk-shaped zirconia samples (30 samples of Novi brand and 30 samples of Rainbow brand) were used (diameter of 10 mm and thickness of 4 mm). Based on surface treatment, the samples were randomly divided into 3 groups: control, air-particle abrasion, and Zircos-E Etching Solution. Using the metal mold, the porcelain was veneered on the zirconia surface and then fired. Then, all samples were subjected to shear bond strength testing using a universal testing machine at a speed of 1 mm/min until breaking. Results: There was a statistically significant difference between the mean variable shear bond strength of the control group and two other groups, so the shear bond strength in the control group was less than in both groups. And there was no statistically significant difference between the mean variable of shear bond strength in the two groups of “airborne particle abrasion” and “Etching”. There was a statistically significant difference between the mean shear bond strength of the two types of zirconia samples and this amount was lower in Novi than in Rainbow. There was also no interaction between the type of surface preparation and the type of zirconia. Conclusion: It can be concluded that surface preparation with air particle abrasion and etching increases the shear bond strength of zirconia to porcelain veneer and the shear bond strength of zirconia and porcelain veneer is affected by the type of zirconia.

Effect of Mg Content and Cooling Rate After Solidification on the Mechanical Properties of T5-treated Al-Si-Mg Alloy

The effects of Mg content and cooling rate on the T5 treatment of Al-Si-Mg alloys have been investigated using Avrami kinetics and transmission electron microscopy. The alloys were super-heated at 800 oC for 1 hr followed by degassing treatment at 720 oC for 15 min, and poured into a metallic mold preheated to 250 oC. The as-cast alloys were then T5-treated at a temperature of 190 oC. As the Mg content and/or cooling rate increased, the strength of the T5-treated alloys increased while the elongation decreased over the entire aging time. However, some T5 treatment conditions were effective to at enhancinge elongation as well as strength. The alloy with low Mg content showed excellent elongation in the early stage of aging. B, but as the aging time increased, h. However, the elongation decreased rapidly so that there was showed no significant difference from with the alloy with high Mg content in the over-aging stage. This was due to a coarse and agglomerated precipitate structure, which were likely to be formed by the rapid precipitation and agglomeration of the β′ phase. The alloy with a high cooling rate exhibited superior strength with similar elongation over the entire aging time compared to the slowly cooled alloy. The reason for the decrease in strength for in the slowly cooled alloy was attributed to the coarsening of precipitates and suppression of the formation of fine precipitates during cooling.

Production of B4C Reinforced Composite Materials and Investigation of Their Bending Strength

In this study, AA2024 aluminum alloy was selected as the matrix material, while B4C was selected as the reinforcement material, and particle-reinforced Al-matrix composite materials were produced using the powder metallurgy method. Examinations were made to determine the effects of different reinforcement particle ratios and sintering temperatures on the mechanical properties of the AA2024 matrix composite materials that were produced. The powders were compressed in a metal mold at room temperature and a pressure of 525 MPa under a uniaxial press. The raw specimens that were obtained were sintered for 45 minutes at different temperatures. The produced composite materials were subjected to three-point bending tests and hardness measurements. Optical microscopy analysis was carried out for characterization. The results allowed us to draw a conclusion on how the reinforcement material in the produced specimens affected Al-matrix composite properties. It was determined that the B4C reinforcement added to the matrix increased the hardness values of the composites at all sintering temperatures, the highest bending strength was obtained in the composite with 10% B4C particle reinforcement, and in general, the B4C reinforcement was homogeneously dispersed in the matrix. Increased B4C reinforcement ratios resulted in higher hardness values in the composite materials.

Producing Metal Powder from Machining Chips Using Ball Milling Process: A Review.

In the pursuit of achieving zero emissions, exploring the concept of recycling metal waste from industries and workshops (i.e., waste-free) is essential. This is because metal recycling not only helps conserve natural resources but also requires less energy as compared to the production of new products from virgin raw materials. The use of metal scrap in rapid tooling (RT) for injection molding is an interesting and viable approach. Recycling methods enable the recovery of valuable metal powders from various sources, such as electronic, industrial, and automobile scrap. Mechanical alloying is a potential opportunity for sustainable powder production as it has the capability to convert various starting materials with different initial sizes into powder particles through the ball milling process. Nevertheless, parameter factors, such as the type of ball milling, ball-to-powder ratio (BPR), rotation speed, grinding period, size and shape of the milling media, and process control agent (PCA), can influence the quality and characteristics of the metal powders produced. Despite potential drawbacks and environmental impacts, this process can still be a valuable method for recycling metals into powders. Further research is required to optimize the process. Furthermore, ball milling has been widely used in various industries, including recycling and metal mold production, to improve product properties in an environmentally friendly way. This review found that ball milling is the best tool for reducing the particle size of recycled metal chips and creating new metal powders to enhance mechanical properties and novelty for mold additive manufacturing (MAM) applications. Therefore, it is necessary to conduct further research on various parameters associated with ball milling to optimize the process of converting recycled copper chips into powder. This research will assist in attaining the highest level of efficiency and effectiveness in particle size reduction and powder quality. Lastly, this review also presents potential avenues for future research by exploring the application of RT in the ball milling technique.

Methodology for Creating a Software for Structuring the Reconstruction Technologies by Laser Welding of Metal Moulds

Abstract Metal and plastic parts are made in moulds, in production processes such as plastic injection, metal alloy die casting and metal deformation. During operations, moulds are exposed to severe conditions: wear, impact, corrosion, thermal cycling and high mechanical stresses. Moulds reconstruction has advanced, precisely because to new technologies, such as laser welding. Laser technologies offers several benefits, including increase of work speeds, reduced thermally influenced zones and material losses and decreased additional working times for mechanical machining processes.

CHARACTERIZATION OF PRODUCED BIODEGRADABLE BRAKE-PAD FROM WASTE COCONUT FRUIT FIBER AND OYSTER SEA SHELLS AS REINFORCEMENT MATERIALS

In the present research, organic materials (coconut fruit fibres CFF and oyster sea shells OSS) were used as a substitute for asbestos materials. The waste CFF and OSS were washed, crushed, grounded, and sieved to different sizes. The sieved CFF and OSS as reinforcement materials were prepared in three different levels, K1, K2, and K3, with addictive such as phenolic resin, graphite, copper, and hardener. Level K1 has 50% of OSS and 0% of CFF, K2 has 50% of CFF and 50% of OSS, while K3 has 50% of CFF and 0% of OSS. The prepared levels were moulded in clean metal moulding plates up to twenty-seven (27) runs using the Box Behnken Design technic of four factors and three levels. The 27 produced brake pads and commercial brake pad CBP were tested in a laboratory to determine their characterization, such as; thermal conductivity, thermos gravimetric analysis (TGA) and wear rate. The characterization of the produced brake pad has a related standard brake pad coefficient of friction of 0.3 – 0.45 while that of produced brake pad PBP has the lowest TGA of S3232 - 25.44% than CBP 41.90% and PBP of S3122 has the lowest wear rate of 3.17 than CBP 3.92g. From the evaluation, the PBP were superior and performed best in braking application.