Metal Mold Research Articles

Mechanical performances of composite orthogrid stiffened cylinder manufactured by an improved method

With high specific strength and stiffness, composite orthogrid stiffened cylinder (COSC) possesses excellent potential in the aerospace industry. However, the traditional silicone mold preparation methods have poor manufacturing accuracy and a low reuse rate of the mold. This work presents an improved COSC manufacturing method based on a combined metal mold and prepreg laying process. High-precision COSCs with intersection fillets were manufactured by the improved method. Axial compression was performed to reveal the strength and failure mode of the cylinder. Rib fracture and end delamination are the primary failure modes of the COSC under compression. Compared with relevant cylinders, the peak failure load, specific compression strength, and compression stiffness of the cylinder are significantly improved. Fillets wrapped around the intersection can effectively protect the fragile intersection roots. On this basis, an explicit dynamic simulation method simultaneously considering linear buckling mode and Hashin failure criterion is proposed to predict the peak failure load and fracture behavior of the cylinder.

Evaluation of Coconut Fibre Reinforced Low Density Polyethelene Composites

Physical, mechanical and dynamic properties of composites produced from coconut fibres using pure water sachet (LDPE) as matrix were evaluated in this study in order to assess its suitability for use as particleboards. The LDPE (waste water sachets) and coconut coir/fibre were collected, shredded and milled into pellets. Five compositions with coconut fibre loading 5, 10, 15, 20, and 25%, and corresponding LDPE of 95, 90, 85, 80 and 75%. A sixth sample with 100% LDPE was also produced as control. The LDPE samples were heated at 170°C for 30 minutes, and each melted solution was loaded with the corresponding coconut fibres and the mixture stirred and poured into a pre-designed metallic mould, pressed and cured in air for 24 hours. The results show that water absorption, swelling thickness and flaking concentration increased with, while the density decreased. The bending strength decreased with fibre loading, while the tensile strength, compressive strength and modulus of elasticity increased with increasing loading to a point before decreasing sharply. The results of dynamic mechanical analysis for the storage and loss modulus shows that as the temperature of the samples was increased these properties reduced except for the damping factor which increased. On the whole, the results showed that the sample with 15% coconut fibres loading and 85% LDPE exhibits more desirable properties compared with the others. These results imply that the composites produced from coconut fibres with LDPE as a matrix can be used as particleboards as well as in areas other areas of applications in the automobile industries. This will improve on savings in foreign exchange and mitigate environmental degradation as result of indiscriminate disposal of portable water sachets and coconut fibres.

A Novel Approach of Optimum Time Interval Estimation for Al-7.5Si/Al-18Si Liquid-Liquid Bimetal Casting in Sand and Metallic Moulds.

This work describes a novel approach for Al-7.5Si/Al-18Si liquid-liquid bimetal casting in sand and metallic moulds. The aim of the work is to facilitate and develop a simple procedure to produce an Al-7.5Si/Al-18Si bimetallic material with a smooth gradient interface structure. The procedure involves the theoretical calculation of total solidification time (TST) of the first liquid metal (M1), pouring the liquid metal (M1), and allowing it to solidify; then, before complete solidification, the second liquid metal (M2) is introduced into the mould. This novel approach has been proven to produce Al-7.5Si/Al-18Si bimetal materials using liquid-liquid casting. The optimum time interval of Al-7.5Si/Al-18Si bimetal casting with modulus of cast Mc ≤ 1 was estimated based on subtracting 5-15 s or 1-5 s from TST of M1 for sand and metallic moulds, respectively. Future work will involve determining the appropriate time interval range for castings having modulus ≥ 1 using the current approach.

Characterization and corrosion behavior of composites reinforced with ZK60, AlN, and SiC particles

In this paper, microstructure, mechanical, immersion and potentiodynamic corrosion behaviours of extruded ZK60 matrix composites reinforced with forty-five µm 15% silicon carbide (SiC) particles and aluminium nitride nanoparticle (AIN) (0.2–0.5% 760 nm) were investigated. The SiC and AlN mixtures, which are the reinforcing elements of the composites, were first mixed with magnesium powder as the main alloy, then pressed under a pressure of 450 MPa and sintered at 420 °C. Second, the sintered compacts are placed in the ZK60 alloy matrix at the semi-solid melting temperature, and the melt is mixed mechanically. After the melts are mixed for 30 min and a homogeneous mixture is obtained, the mixtures are poured into metal moulds and composite samples are produced. After homogenization for 24 h at 400 °C, the composite samples were extruded at 300 °C with an extrusion ratio of 16:1 and a piston speed of 0.3 mm/s. Then, microstructure characterization of all composite samples was performed and potentiodynamic and immersion corrosion behaviours were analyzed in 3.5% NaCl solution. It was seen that the corrosion resistance increased depending on the percentages of SiC and AlN reinforcement elements in the matrix. As a result, it was seen that the potentiodynamic corrosion resistance of reinforced ZK60 + 15% SiC (ZK60SiC15), ZK60 + 15% SiC + 02AIN (ZK60SiC15AlN0.2) and ZK60 + 15% SiC + 0.5% AIN (ZK60SiC15AlN0.5) compounds increased by 1.6, 1.8 and 3.5 times compared to the unreinforced ZK60 alloy. The immersion corrosion rates were calculated as 2090.73, 1748.19, 1479.84 and 1397.79 (mg/year) for the unreinforced ZK60, ZK60SiC15, ZK60SiC15AlN0.2 and ZK60SiC15AlN0.5 reinforcements, respectively. As a result of the SEM and elemental spectrum response analysis of the corrosion surfaces, the presence of a layer rich in Si-O elements on the surface of the AlN + SiC reinforced composites enhanced corrosion resistance. Additionally, the formation of the Mg2Si intermetallics in the structure of the SiC reinforced composites improved corrosion resistance, according to the XRD results.

Impact of metal mould vibration on the mechanical properties of aluminium 6082 t6 alloy

ABSTRACT Casting is a technique used to prepare machinery parts. Casting during vibration is one of the techniques used to improve the properties of material. In this paper, the effect of mould vibration on the properties of gravity die casting alloys is studied. This process decreases the porosity, holes and increase in the grain refinement of cast alloy. Aluminium 6082 T6 alloy is made by casting process, with and without vibration. The frequencies varied from 0 Hz to 45 Hz. The material is tested on electronic tensiometer and vickers hardness to check its tensile strength and hardness. The outcomes showed improvement in grain refinement and properties when vibration is applied during casting. With this improvement, it can be widely used in trusses, bridges, cranes and transport applications.

Performance evaluation of metal mould for casting aluminium alloy (AA6063) of scientific products in National agency for science and engineering infrastructure

The study investigated the major Causes of inconsistency in the cast results of the aluminium cast products from the metal moulds supplied by the then Hungarian Technical Partners to Scientific Equipment Development Institute, Minna. The metal moulds for different scientific products for Schools Scientific Laboratories were to achieve mass production of these products. The aluminium alloy A6063 ingot used were likewise imported. However, another consignment of the ingot used is produced in Nigeria by Nigerian Aluminium Extrusion Company, Lagos. Result of the products defects including shrinkage, blow holes, etc. remained the same, hence the need for this investigation work to ascertain the causes traceable to either moulds or the class or group of alloys.The outcome as shown could be that pouring speed or melting temperature etcetera are responsible for the inconsistency in obtaining acceptable cast products at different operations and with these moulds. A particular product mould gives inconsistent cast products and varying defects. This is applicable to all the available moulds supplied to the Institute at the same time.

The Different Polishing Systems Effect on Ormocer and Supranano Spherical Filler Composite Resin Surface Roughness

Background: The polishing procedure is an essential step in composite resin restoration. There are two types of polishing systems, which are one-step and multi-step polishing systems. Purpose: This study aimed to identify the effect of different polishing systems on the surface roughness of ormocer and supranano spherical filler composite resin. Material and Methods: This study was conducted in an experimental laboratory. The specimens were ormocer and supranano spherical filler composite resin filled in a cylindric metal mold. The total of specimens was thirty-two (n=32) of each composite resin. Each composite resin specimen was divided into four groups, then polished using PoGo (group 1 – one-step polishing system), Optrapol (group 2 – one-step polishing system), Sof-lex (group 3 – multistep polishing system), and Optidisc (group 4 – multistep polishing system). Specimens were incubated at 37℃ for 24 hours. Subsequently, specimens were assessed with a stylus profilometer surfcorder SE 1700. Data were analyzed using an independent t-test and one-way ANOVA. Result: There was a significant difference in surface roughness of the one-step and multistep groups (p ≤ 0.05). The lowest surface roughness value was in the Sof-Lex disc group (0.4026μm), and the highest surface roughness was in the PoGo group (1.1036μm). Conclusion: Based on composite resin, supranano spherical filler had less surface roughness than ormocer (p ≤ 0.05). Furthermore, both ormocer and supranano spherical filler polished using a multistep polishing system had lower surface roughness than those polished using a one-step polishing system.

Surface properties of molds for powder injection molding and their effect on feedstock moldability and mold adhesion

The surface energy of various mold materials for low-pressure powder injection molding was evaluated using values of contact angles (Owens–Wendt method), and correlated with the feedstock moldability and mold adhesion. The surface tension of the binder used to formulate a metallic-based feedstock was also measured in the molten state at a typical injection temperature using the pendant drop technique. Real-scale injection tests were performed into metallic and polymeric mold cavities to assess the feedstock moldability and its adhesion with the mold surfaces that were compared with theoretical predictions obtained from the surface energies values. The results confirmed that the adhesion was significantly affected by the interfacial energy between the mold and the binder—in this case, the metallic mold exhibited low adhesion as compared to the polymeric mold. It was finally demonstrated that the adhesion phenomenon is only related to the surface properties of the mold (i.e., they are not related to the solidification rate)—in this case, a gold-coated polymeric mold produced the moldability of a polymeric mold and the adhesion properties of a metallic mold, which translated into a high moldability potential, with no resulting adhesion of the feedstock with the mold.

Composite Mould Design with Multiphysics FEM Computations Guidance

Composite moulds constitute an attractive alternative to classical metallic moulds when used for components fabricated by processes such as Resin Transfer Moulding (RTM). However, there are many factors that have to be accounted for if a correct design of the moulds is sought after. In this paper, the Finite Element Method (FEM) is used to help in the design of the mould. To do so, a thermo-electrical simulation has been performed through MSC-Marc in the preheating phase in order to ensure that the mould is able to be heated, through the Joule’s effect, according to the thermal cycle specified under operating conditions. Mean temperatures of 120 °C and 100 °C are predicted for the lower and upper semi-mould parts, respectively. Additionally, a thermo-electrical-mechanical calculation has been completed with MSC-Marc to calculate the tensile state along the system during the preheating stage. For the filling phase, the filling process itself has been simulated through RTM-Worx. Both the uniform- and non-uniform temperature distribution approaches have been used to assess the resulting effect. It has been found that this piece of software cannot model the temperature dependency of the resin and a numerical trick must have been applied in the second case to overcome it. Results have been found to be very dependent on the approach, the filling time being 73% greater when modelling a non-uniform temperature distribution. The correct behaviour of the mould during the filling stage, as a consequence of the filling pressure, has been also proved with a specific mechanical analysis conducted with MSC-Marc. Finally, the thermo-elastic response of the mould during the curing stage has been numerically assessed. This analysis has been made through MSC-Marc, paying special attention to the curing of the resin and the exothermic reaction that takes place. For the sake of accuracy, a user subroutine to include specific curing laws has been used. Material properties employed are also described in detail following a modified version of the Scott model, with curing properties extracted from experiments. All these detailed calculations have been the cornerstone to designing the composite mould and have also unveiled some capabilities that were missed in the commercial codes employed. Future versions of these commercial codes will have to deal with these weak points but, as a whole, the Finite Element Method is shown to be an appropriate tool for helping in the design of composite moulds.

The Production of B4C Particle-Reinforced Composite Materials with the Powder Metallurgy Technique and Examination 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. B4C ceramic powders were added to the AA2024 matrix. Examinations were made to determine the effects of different reinforcement particle ratios and sintering temperatures on the mechanical properties of the composite materials that were produced. The powders were homogeneously mixed and 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 composite properties.

Thermoplastic composite connecting rods

Engineering carbon fiber thermoplastics have been used in the development and optimization of composite connecting rod(s) with design requirement of bearing 14,000 N and 1 mm maximum deflection. The studies featured engineering thermoplastics- 30 wt percent carbon fiber poly ether ether ketone (C-PEEK) long fiber thermoplastics (LFT) injection over molded in conjunction with 70 wt percent carbon/polyphenylene sulfide (C-PPS) and carbon/poly ether imide (C-PEI) tapes. Over molding of thermoplastic tapes has been investigated in terms of number of tape winding around the small and big end, and different winding patterns within the connecting rod geometry. The design was progressively optimized for the geometry of the connecting rod, i.e., increasing the wall thickness of the small end and width of the center section. The effect of over molded metal bushing with C/PEEK LFT at the bearing surfaces was also investigated. The material and geometry optimization successfully met 14,000 N while several design iterations were necessary to meet the 1 mm deflection limit constraint. Finite element analysis (FEA) was adopted to optimize the increase of the width of the center section width and wall thickness of the small end. The optimized composite connecting rod was estimated to be 78% lighter than the steel incumbent.

Analysis of Aluminium Filling in Cylindrical Pipe under High Pressure by Experiment and Mathematical Modelling

The preferred method for producing lightweight metal components, mainly from aluminum and magnesium alloys, is through high pressure die casting. This process involves rapidly and forcibly injecting liquid metal into a metal mold under high pressure. Our study aims to compare results obtained from the numerical modelling of the filling of aluminum under high pressure with the experimental results. Two different cylindrical pipes are used. The results indicate for imposed values of KE = 14 and KW = 60 for pipe 1(Dentry/Drp=40/40) and pipe 2 (Dentry/Drp=16/40) respectively, the mathematical model with the same initial conditions gives some results which are close to the experimental data. The results also indicate that pipe 2 is damped faster than pipe and this is due to the singular pressure loss at the entry.

Influence of the casting process on corrosion behaviour of 2024-T6 aluminium alloy in different conditions of pH and NaCl concentration

ABSTRACT Corrosion behaviour of 2024-T6 castings produced by sand mould and metallic mould has been studied in media with different sodium chloride concentrations and pH values, using electrochemical techniques and scanning electron microscope. Corrosion rates and anodic and cathodic reaction kinetics are detailed to provide a fundamental understanding of the electrochemical behaviour of 2024-T6 at different conditions. The study shows a different corrosion mechanism depending on the pH. At pH 12, the more negative values of E corr confirmed that the alkalinisation of aluminium incites the dissolution of the Al substrate. The effect of chloride concentration is reflected in shifts of E corr towards more negative values. The research on the effect of the used mould demonstrates that the impact of the casting process in the cooling rate affects the pitting corrosion resistance.

Comparative evaluation of the antibacterial efficacy of a bioactive material enhanced by phytosynthesized nanoparticles: An in vitro study

ABSTRACT Aim: To evaluate and compare the antibacterial efficacy of ACTIVA Bioactive base/liner (ABBL) enhanced with phytosynthesized titanium dioxide nano-particles (nTiO2) and nano-curcumin (nCur). Methods: nTiO2 (3%) was phytosynthesized from moringa leaves extract and characterized. nCur (7%) was synthesized from Curcumin taken in dichloromethane and sprayed into boiling water. Metal molds with a diameter of 5 mm were placed on a glass slab and filled with ABBL (Group 1) and cured. For Group 2 (ABBL + nTiO2), 3% phytosynthesized titanium dioxide (TiO2) was added to ABBL and cured. For Group 3 (ABBL + nCur), ABBL discs were fabricated and 7% nCur was surface-coated on these discs and cured. Seven samples for each group with a total sample size of 42 specimens were assessed for anti-biofilm efficacy against Streptococcus mutans at the end of 1 day and 7 days and expressed in colony forming units. Intergroup and intragroup comparison of colony counts was assessed using the one-way analysis of variance and paired t-test, respectively. Level of significance was set at 0.05. Results: Intergroup comparison on day 1 and 7 showed significant difference (P = 0.016/P = 0.002) amongst the test groups, where Groups 3 and 1 showed maximum increase in bacterial colonies, respectively, and Group 2 showed minimum. On intragroup comparison, all groups showed an increase in mean colony counts from day 1 to 7, with significant difference only in Group 1 (P = 0.004). Conclusion: ABBL + 3% TiO2 showed superior results. The antibacterial activity of ABBL decreased with time whereas, ABBL + 7% nCur showed sustained release during the tested time.

Uticaj termootporne obloge na parametre fazne transformacije tokom formiranja Al-8wt%Si-3wt%Cu strukture

Solidification of the aluminum alloys takes place in heat-resistant refractory materials made of either metal or oxides that are stable at high temperatures. The significantly different thermal conductivities between metals and heat-resistant oxides cause solidification with significantly different cooling rates. In this work, we formed a secondary Al-8wt%Si-3wt%Cu alloy in a stainless steel mould, a thin-walled stainless steel cup, and a thick-walled zirconium oxide cup. The course of the formation of the solidified structure was monitored by immersed thermocouples, which enabled the computer analysis of the cooling curves. The parameters on which the cooling rate had the most significant influence are the undercooling values of the formation of primary aluminum crystals, the time of the growth of primary aluminum crystals and the total solidification time from the formation of the first solid crystals to the formation of a fully solidified structure. The Al-8wt%Si-3wt%Cu aluminum alloy formed in metal mould has a smaller grain size and consequently higher tensile strength, lower macro-porosity and less rough surface than the alloy formed in refractory oxide coatings. The examined heat-resistant refractory material influenced the formation of three basic micro-constituents in the Al-8wt%Si-3wt%Cu alloy in different time intervals, which led to the formation of a different microstructure, where the decision on the choice of material for the heat-resistant refractory material depends on the profitability of the entire process, the required quality of the external surfaces and required minimum strength of the final product.

Characteristics of Plastic Block Wall Materials (PBWM) Using Waste Engine Oil, Crackle Plastic, Mineral Water Plastic Cups Cover and Label of Plastic Bottle Without and With Rice Husk Ash and Natural Aggregates Filling Materials

The increase of waste in Indonesia has reached 38 million tons per year and about 30% of this waste are plastic. One of the efforts is to overcome this issue is by using thin plastic waste from packaging which is rarely recycled to become plastic blocks wall material (PBWM), where the plastic was melted in hot waste engine oil (WEO). The main purpose of this study was to analyze the characteristics of the PBWM. Variation of material proportion was based on trials. The plastic waste was initially shredded to sizes about 5-10mm. On sample productions, the WEO was heated to 200°C then the shredded plastic gradually added and evenly mixed, and poured into a metal mould. The mixture was cooled down to ideal temperature for compaction of 110°C to 125°C, then left to reach room temperature. It was obtained that the Initial Rate of Suction (IRS) test results range from 0.0982-0.1012 kg/ 2.

Peat Soil Compaction Characteristic and Physicochemical Changes Treated with Eco-Processed Pozzolan (EPP)

Peat soil was defined as the highly organic surface layer derived primarily from plant remains. Peat, on the other hand, was the subsurface of wetland systems, consisting of unconsolidated superficial layers with a high non-crystalline colloid (humus) content. Peat soils have a low shear strength of 5 to 20 kPa, a high compressibility of 0.9 to 1.5, and a high moisture content of >100%. The purpose of the study was to prognosticate the potential of Eco-Processed Pozzolan (EPP) as peat soil stabilization material with improved technique and its consequence of the methods, which was the peat soils index properties and analyse the characteristics of the peat soil stabilization before and after treatment using Eco-Processed Pozzolan (EPP). The soil was mixed with 10, 20, and 30% Eco-Processed Pozzolan (EPP) and then compacted (compaction test) in a metal mould with an internal diameter of 105 mm using a 2.5 kg rammer of 50 mm diameter, freefalling from 300 mm above the top of the soil Three layers compaction of approximately equal depth and 27 blows spread evenly over the soil surface for each layer. The expected result to accomplish the main purpose was to prognosticate the potential Eco-Processed Pozzolan (EPP) as peat soil stabilization material with improved technique and its consequence of the methods. According to the findings, peat soil treated with EPP will transform its qualities from peat to usable soil. However, the presence of moisture will reduce the mixture's ability. According to the findings of this study, the optimum EPP for stabilizing peat soils was 30-40%. Correspondingly, the elemental composition of peat soil mixed with EPP improved regardless of Carbon, Ca composition. Comparatively, the amount of Silicon, Si increased from 6.5% (Peat + EPP 10%) to 12.9% (Peat + EPP 40%) due to the crystallization of EPP and peat. Doi: 10.28991/CEJ-2023-09-01-07 Full Text: PDF

INCREASING THE DURABILITY OF EXTERIOR PARTS OF AGRICULTURAL MACHINERY USING COMPOSITE MATERIALS

The problem of ensuring the durability of machines is currently extremely relevant, since the aging of the fleet of machines is outpacing the pace of the necessary technical re-equipment. The use of traditional metal materials and outdated technologies in the designs of agricultural machines leads to an increase in the cost of their production, a decrease in resource and durability. The use of corrosion-resistant materials, such as polymer composites, for exterior elements allows to increase the durability of agricultural machinery and reduce corrosion-related damage. (Research purpose) To perform an analytical review of production methods by which it is possible to manufacture exterior parts of agricultural machinery from composite materials. (Materials and methods) It was determined that the material of this study is open information sources; the research method consists in the collection, study and comparative analysis of information. (Results and discussion) It was noted that the following technologies are used for the production of exterior parts of agricultural machinery: vacuum molding, contact molding, pressure impregnation, injection molding. Vacuum forming consists in the production of materials in hot form by the method of exposure to vacuum or low air pressure. Contact molding is a manual layering of reinforcing material and impregnation of each layer with resin. When impregnated under pressure, the fibrous billet is placed in the inner mold, leaving a gap that allows the resin to be injected and the fibers to be impregnated. The essence of injection molding is the forced filling of the working cavity of the metal mold with melt and the formation of the casting, which occurs under the action of the press piston. (Conclusions) Distinctive features of the exterior elements of agricultural machinery are their large overall dimensions and low requirements for the accuracy of shapes and sizes, which determines the scope of technologies possible for their manufacture. The least labor-intensive and simply implemented in a single production method is contact molding. In mass production, the most suitable method is injection molding.

Rubber Mixing and Molding Processing Technology

Rubber processing technology including compound design, extruding, and metal mold cure are closely related each other. Especially mixing technology are most important for extruding metal mold cure to produce the high quality products. Because the processing index such as pressure losses of rubber compound are important for establish the most desireble producing condition to produce high quality products. In this report, the relation between mixing index and processing technology of rubber compounds will be discusse.

Mo-rich layer formation on maraging steel and surface modification by large-area electron beam irradiation

Maraging steels have been typically applied to precise metal mold and products in aerospace industry, since they have excellent properties such as high strength and toughness. However, the maraging steels are inferior to other steels in some surface functions such as corrosion resistance. Hence, it is necessary to improve surface functions of maraging steel. On the other hand, large-area electron beam (EB) of 60 mm in diameter can instantly melt metal surface. Our previous study clarified that the surface roughness of alloy tool steels such as SKD11 in JIS specification could be reduced efficiently by the EB irradiation. Furthermore, the surface characteristics were also improved by formation of thin re-solidified layer with a fine microstructure. In this study, formation of Mo-rich layer in re-solidified layer on maraging steel surface by large-area EB irradiation was investigated. Mechanism for formation of Mo-rich layer was discussed by unsteady heat conduction analysis. In addition, surface finishing and improvement of surface characteristics of maraging steels by the EB irradiation were also examined. The experimental results show that surface roughness decreases to approximately 1.0µm R z in a few minutes under low energy densities conditions, and Mo-rich layer with thickness of a few micrometers is self-formed in re-solidified layer of EB irradiated surface. Moreover, water repellency, corrosion resistance and wear performance are improved by the formation of Mo-rich layer in re-solidified layer. Therefore, maraging steel surface can be finished and modified simultaneously by large-area EB irradiation method.