Properties Of Mold Research Articles

Influence of Slurry Composition on Mould Properties and Shrinkage of Investment Casting

Ceramic shell mould plays a key role in achieving dimensional accuracy and quality of casting. This work investigates the effect of mould parameters such as silica concentration, filler to binder ratio and the number of secondary coats on mould properties, namely modulus of rupture, adjusted fracture load, and permeability. Experimental results report that enrichment in silica results in drastic growth in adjusted fracture load with a small increase in modulus of rupture and no change in permeability. Improvement in filler to binder ratio causes a significant increase in the adjusted fracture load and modulus of rupture with moderate decrease in permeability. An increase in number of ceramic coats increases the adjusted fracture load significantly and reduces permeability moderately. Impact of the adjusted fracture load on casting shrinkage has been studied by conducting various casting trials. Adjusted fracture load above 315 N is preferred which corresponds to 25–30% silica, filler to binder ratio of 1.25 and number of secondary coats as six to eight for reduced shrinkage variation.

Investigation on the Influence of Different Additives on Properties of Green Sand Mould

Green sand mixtures which are used for moulding purposes in foundry industries should possess sufficient green compression strength, flowability, toughness and air-permeability. Usually, the aforementioned properties for a particular casting differ due to variation in composition of the moulding sand mixtures, sand grain shape and size, bonding capacity of the binder, type and quantity of additives used, etc. The present work focuses on the effect of various additives namely, camphor powder, coconut shell ash, mixture of camphor powder and coconut shell ash at diverse proportions on permeability and green compression strength of the sand moulds. The quantity of the aforementioned additives for experimentation was varied from 0.5 to 3.5 wt. %. It was found that the mould’s permeability increased on addition of 1 wt. % additives for all cases. Similarly, the optimum quantity of additives that needs to be added to the sand mixtures for enhancing green compression strength was found to be 2 wt. %. Among all the additives used for improving the mould’s permeability, substitution of camphor exhibited best results. The green compression strength was found to be highest for the coconut shell ash containing sand mould. The moulding sand containing a combination of camphor powder and coconut shell ash between 1 to 2 wt. % exhibited fine mould permeability along with sufficient green strength.

Towards Functionally Graded Sand Molds for Metal Casting: Engineering Thermo-mechanical Properties Using 3D Sand Printing

Growing applications of additive manufacturing (AM) have now been adopted for metal castings via indirect hybrid AM, i.e., 3D sand printing (3DSP). A comprehensive study on the thermo-physical properties of 3DSP molds based on 3DSP processing conditions and their effects on materials and mechanical properties of resulting aluminum castings is presented. The effect of furan binder content (i.e., 1–3%) on as-printed 3DSP molds is evaluated to determine changes in dimensional accuracy, density (helium pycnometry), actual binder content (loss on ignition) and mechanical strength (three-point bending and tensile testing) and thermal properties (transient plane source technique and casting runs). Pore network characterization via mercury intrusion porosimetry does not reveal any significant differences in the morphology of pore structures due to varying binder concentrations. However, bulk permeability is reduced with increasing binder content. Thermal analysis shows a reduction in conductivity and heat capacity due to binder degradation. Findings from this study will enable the optimum selection of binder content for functional grading of 3DSP molds/cores for adequate degassing and mechanical strength, which is ready for adoption by both foundries and 3DSP service providers.

Modeling and Simulation of Heat Transfer Phenomenon Related to Mold Heating during Investment Casting

Cast shape during investment casting process dictates properties and service life of the casting. These properties are the function of cast part parameters (both static and dynamic), part geometry and hence mold geometry, nature and type of metal being cast, properties (extrinsic and intrinsic) and processing parameters (rate of heating, rate of cooling, rate of pouring). Improper and inadequate manipulation and modification of mold properties degrade the properties and life of casting altogether. A mathematical model is developed using standard transport equations incorporating all heat transfer coefficients (HTCs) to determine the effect of external mold heating on the properties of the final casting and a simulation is performed in C++ to validate it against experimental results. Pure iron is casted in investment molds of silica sand with zircon coating. Airflow near the mold surfaces was partially restricted due to geometry of the molds and arrangement of the pieces around a tree. The variations in heat transfer coefficient contribute towards total heat transfer out of mold surface. External heating is found to be very effective for improved casting properties. The mold heat transfer profile is found to be in good agreement with experimental values validating the effectiveness of mold heating.

Performance of kaolin and cassava starch as replacements for bentonite in moulding sand used in thin wall ductile iron castings

Thin Wall Ductile Iron (TWDI) casting presents macroscopic and microscopic challenges using bentonite bonded moulding sand. In this study, moulding properties of bentonite, cassava starch and kaolin bonded silica sand were evaluated using various binder/sand formulations (6%, 9%, and 12%). TWDI samples of 3 mm thickness were cast using dry compression strength as criteria for each binder type. Cast samples were subjected to macroscopic, microscopic and Vickers hardness analysis. Kaolin bonded sand gave superior dry strength property of 650 KN/m 2 at 6 % addition. Samples showed nodularity and nodule counts of 96.2%, 587 nodules/mm 2 , 76.2%, 61 nodules/mm 2 and 96.5%, 985 nodules/mm 2 using kaolin, cassava starch and bentonite bonded sand respectively. Thickness deviations were observed in all samples, bentonite bonded samples being most significant. This study has shown that adopting kaolin as alternative binder for production of TWDI casting should be encouraged as properties of cast TWDIs samples were greatly improved. Keywords: Thin wall ductile iron (TWDI), binder/sand formulations, moulding sand properties, macroscopic and microscopic properties

Development of shrinkage model of micro structured vitreous carbon mold for glass molding

Carbonization of replicated furan precursors has been proposed as a low-cost large-area method for fabricating microstructured vitreous carbon (VC) molds to glass micromolding. During the carbonization of furan precursors, large anisotropic shrinkage occurs inherently owing to thermal decomposition of the material, and this anisotropic shrinkage should be compensated to obtain the designed profiles of microcavities on the VC mold. In this study, a linear gradual shrinkage ratio model (LGSRM) was developed to predict the anisotropic shrinkage characteristics associated with the fabrication of microstructured VC molds. To verify the shrinkage model, the shape change of the VC mold according to the LGSRM was simulated with ANSYS and compared with the experimental results. To determine the coefficients of LGSRM, a finite element analysis code, in which a gradual shrinkage ratio can be assigned to each individual mesh, was developed, and the coefficients of LGSRM were selected to minimize the errors between the simulated and measured geometrical properties of the VC mold.

Mycelium bio-composites in industrial design and architecture: Comparative review and experimental analysis

Recent convergence of biotechnological and design tools has stimulated an emergence of new design practices utilizing natural mechanisms to program matter in a bottom-up approach. In this paper, the fibrous network of mycelium—the vegetative part of fungi—is employed to produce sustainable alternatives for synthetic foams. Current research on mycelium-based materials lacks essential details regarding material compositions, incubation conditions, and fabrication methods . The paper presents the results of ongoing research on employing mycelium to provide cleaner architecture and design products with sustainable lifecycles. The paper opens with a critical review of current projects, products, and scientific literature using mycelium in design and architecture. In the second section, material properties of varied fungi-substrate compositions and fabrication methods are evaluated and compared through changes in essential chemical parameters during fermentation, visual impression, water absorbency , and compression strength tests. Then, potential architecture and design implications related to the material properties are discussed. Results indicate a clear correlation between fungi, substrate, mold properties, and incubation conditions on final material characteristics, depicting a clear effect on material density, water absorbency, and the compressive strength of the final bio-composite. Finally, two primary case studies demonstrate implications for mycelium-based composites for circular design and architectural applications. The study shows that in order to produce desirable designs and performance within an inclusive circular approach, parameters such as material composition and fabrication conditions should be considered according to the target function of the final product throughout the design process. • Mycelium employed to upcycle regional tree-pruning waste into cleaner products. • Materials and methods for fabricating mycelium composites are discussed. • Clear correlation is shown between material composition and material properties. • Implications for sustainable architecture and design products are presented.

Performance analysis of cow dung as an eco-friendly additive material for sustainable moulding and casting

In the present work, an attempt is made to partially replace high cost silica sand with sustainable eco-friendly cow-dung. The practical utility of cow dung as an additive material that facilitates binding in sand moulds has been tested. The Taguchi method is used to plan and conduct nine experiments with three replicates each. Pareto analysis of variance study is performed to understand the practical significance of moulding sand variables, that is, percentage of cow dung, clay, water, and degree of ramming on sand mould properties. The conflicting multiple objective functions (maximize mould hardness, and minimize collapsibility and gas evolution) are optimized by utilizing the Data Envelopment Analysis Ranking (DEAR) method. The optimal parameters i.e. 6% of clay, 4% of water, 5% of cow-dung and 4 numbers of ramming strokes are obtained by applying a hybrid Taguchi-DEAR method. These parameters show the best moulding properties are: mould hardness 55, gas evolution 5.9 ml·g−1, and collapsibility 470 g·cm−2. Thereafter, a Lovejoy coupling made of aluminium is cast in the sand mould prepared with cow dung and without cow dung, with the optimum set of parameters. The mechanical properties, surface finish, and microstructure of the casting cast with cow-dung are better than that without cow-dung.

Mathematical Modelling of Process of Shaping of Sand-Pitch Mixes

This article considers mathematical dependences of properties of a casting mold on various parameters of her shaping. The competitiveness in production of castings depends on durability, reliability of the made details, ability to meet requirements and expectations of the consumer of production. Technological process of receiving castings most widespread now in the sandyargillaceous forms (SAF) not completely meets the modern requirements as it is characterized by different types of marriage: gas porosity, scorch, shrinkable sinks, blockages, hot and cold cracks, and others. The bigger quality of castings gives casting in the sand-pitch forms (SPF) in which the high gas permeability and durability are combined, they don’t resist shrinkage, don’t absorb moisture the stiffening alloy and aren’t inclined to an fallibility. However, one of shortcomings of this way of casting is rather high cost binding. One of the directions of decrease in an expense binding is use along with heating of mix for shaping of a cover and static loading. Other direction of decrease in a consumption of mix in general, and binding in particular, is determination of dependence of properties of a shell form on technological parameters that will promote management of properties of a form, decrease in marriage, etc. Formulas of the intense deformed state, density, amounts of heat of the sand-pitch form made at the same time in the conditions of heating and static loading are presented

Multi Response Optimization of Green Sand Moulding Parameters Using Taguchi-DEAR Method

Green sand casting is treated as the most versatile casting process due to their excellent design flexibility that offer complex shapes and ability to reclaim silica sand. The modern foundries are looking for alternate moulding materials to partially replace the high cost silica sand. Cow dung is a naturally available eco-friendly binding as well as additive material and is used to partially replace the silica sand. Improper choice of the combination of moulding sand variables, such as degree of ramming, percentage of cow dung, percentage of clay, and percent of water will affect the moulding sand properties and thereby quality of casting. In the present work, Taguchi method is employed to plan and conduct experiments. Pareto analysis of variance is performed to know the contribution of variables on the moulding sand properties (i.e. compression strength, permeability, loss-on-ignition). Taguchi DEAR method is used to determine the single optimal levels of input factors that enhances the performances of all the sand mould properties. Percent of clay and cow-dung found to be the most dominating factor towards all the sand mould properties.

Slime Mold Quarantine: An Engineering-Design-Integrated Biology Unit

Students often find it challenging to learn about complex and abstract biological processes. Using the engineering design process, which involves designing, building, and testing prototypes, can help students visualize the processes and anchor ideas from lab activities. We describe an engineering-design-integrated biology unit designed for high school students in which they learn about the properties of slime molds, the difference between eukaryotes and prokaryotes, and the iterative nature of the engineering design process. Using the engineering design process, students were successful in quarantining the slime mold from the non-inoculated oats. A t-test revealed statistically significant differences in students' understanding of slime mold characteristics, the difference between eukaryotes and prokaryotes, and the engineering design process before and after the unit. Overall, students demonstrated sound understanding of the biology core ideas and engineering design skills inherent in this unit.

Tribological Performance of PVD Film Systems Against Plastic Counterparts for Adhesion-Reducing Application in Injection Molds

The deposition of physical vapor deposition (PVD) hard films is a promising approach to enhance the tribological properties of injection molds in plastic processing. However, the adhesion is influenced by the pairing of PVD film and processed plastic. For this reason, the friction behavior of different PVD films against polyamide, polypropylene, and polystyrene was investigated in tribometer tests by correlating the relation between the roughness and the adhesion. It was shown that the dispersive and polar surface energy have an impact on the work of adhesion. In particular, Cr-based nitrides with a low polar component exhibit the lowest values ranging from 65.5 to 69.4 mN/m when paired with the polar polyamide. An increased roughness leads to a lower friction due to a reduction of the adhesive friction component, whereas a higher work of adhesion results in higher friction for polyamide and polypropylene. Within this context, most Cr-based nitrides exhibited coefficients of friction below 0.4. In contrast, polystyrene leads to a friction-reducing material transfer. Therefore, a customized deposition of the injection molds with an appropriated PVD film system should be carried out according to the processed plastic.

CONTACT INTERACTION OF MOLDS ELEMENTS AND PROJECT-TECHNOLOGICAL PROVISION OF THEIR TECHNICAL

To analyze the functional properties of molds, it is necessary to determine the stress-strain state of their elements. This is due to the fact that the molds are a set of many parts that are in contact with each other in a power and interaction relationship. To do this, a mathematical model of stress-strain state of molds elements has been developed. This model takes into account the effect of molds locking efforts and the action of the internal pressure of the working material, which is in liquid state, on the surface of the semimatrices. In addition, the conditions of contact interaction process are in place on parts surface that are in combination. This mathematical model is implemented as a set of parametric models and software modules. Using these tools, characteristic features of molds behavior are determined in the implementation of technological operations of pressing plastics parts. Certain features of main parts deformation are determined that provide strength, toughness, accuracy and quality of molds manufactured parts. The analysis of the received results is carried out. Formal recommendations made.

Thermal analysis based method development for novel rapid tooling applications

The use of soft molds manufactured by additive manufacturing is gaining popularity in small-series production, thanks to the development of additive technologies and their materials. The thermal properties of soft molds, however, differ considerably from those of conventional, metal molds, and this greatly affects the conditions in the mold during manufacturing. We investigated the thermal properties and cooling conditions of epoxy acrylate-based, directly manufactured soft prototype molds. We used four different mold inserts, two with conformal cooling, one with conventional cooling and one without cooling. We found that due to the poor thermal properties of the mold material, the thermal conditions in the insert with conventional cooling and the insert without cooling were almost identical, this proves that in this case, conventional cooling cannot remove heat effectively. The use of conformal cooling, however, can reduce the cyclic heat load of mold inserts by about 70%, which increases the lifetime of the mold.

Waste from renewable sources as a polyethylene filler

The paper presents research on the impact of three organic fillers from renewable sources, i.e. ground wheat bran, pumpkin seed husks and peanut shells, constituting production waste of the food industry, on selected mechanical and thermal properties of composite injection moldings based on LDPE. The basic strength properties were tested in a static tensile test, hardness and heat deflection temperature, Vicat softening point, and the microscopic structure of the obtained polymer compositions was analysed. The tests were carried out with a different mass content of fillers of 0, 5, 10, 15 and 20% and variable size of filler grains. Samples for testing were obtained in the injection molding process. An increase in the Young’s modulus and hardness as well as a decrease in the remaining tested strength properties along with an increase in the filler‘s share content were found.

Production of Ceramics Based on the Y2O3–ZrO2–HfO2 System for Casting Molds

The potential of the Y2O3–ZrO2–HfO2 system for synthesizing the casting mold ceramic of the composition 15 mol % Y2O3 : 60 mol % ZrO2 : 25 mol % HfO2 was investigated. The effect of technological parameters on the morphology and main properties of ceramic molds produced by investment casting using the ceramic of the above composition was studied, and the basic recommendations for the further development of their production technology were considered. It was determined that a high-refractory casting mold stable to 2773 K can be obtained by conventional investment casting, in which the solid-phase sintering of the ceramic does not rule out the simultaneous combination with the synthesis of the chosen ternary solid solution of the composition 15 mol % Y2O3 : 60 mol % ZrO2 : 25 mol % HfO2, acting as a high-temperature binder.

Heating properties of ERHCM molds based on heating cell units

A thermal analysis method was developed based on heating cell units to study the thermal response of electrical rapid heat cycle molding (ERHCM) molds. Heating efficiency, mold strength and uniformity of temperature distribution on the mold cavity surface were studied as a function of the distance from the center of heating rods to the mold cavity surface, which is one of the most important parameters for mold design. In this paper, the height/diameter (H/D) value was employed to describe the distance from the center of the heating rods to the mold cavity surface. Additionally, the maximum von Mises stress after heating was determined to describe the mold strength, and the temperature difference was applied to characterize the temperature distribution uniformity of the cavity surface. The results showed that electrical rapid heating cycle injection molds obtain reasonable heating efficiency, mold strength and cavity surface temperature uniformity when the distance from the center of heating rods to the mold cavity surface is approximately 1–1·5 times their diameter.

Microstructure and Mechanical Properties of Characteristic Regions Inside Mold During Mg–Al–Zn Alloy Extrusion Processing

The microstructure and mechanical properties of AZ33 magnesium alloy during forward extrusion processing have been investigated in this paper. The results showed that three characteristic regions exist in the extrusion die, namely dead metal zone (dead zone), shear deformation zone (shear zone), and normal flow zone (normal zone) according to apparently uneven flow behavior. The microstructure of three characteristic zones exhibits a recrystallized, heterogeneous deformation feature. An obvious mechanical anisotropy is obtained in the AZ33 alloy inside the extrusion die. The sample of the normal zone exhibits extraordinary ultimate compression strength of 282.86 MPa but the lowest compression yield strength of 163.99 MPa due to typical $$ (0002) $$ //ED fiber texture. However, the highest compression yield strength of 210.56 MPa achieved in the dead zone is attributed to dislocations hardening and the refinement hardening effect via twin lamellae.

Mechanical Properties of Printed Epoxy-Carbon Fiber Composites

Despite the promise of additive manufacturing (AM) to bring unprecedented agility and design freedom to manufactured components, structural applications remain largely out of reach due to material restrictions – notably the lack of a mature AM process for reinforced thermoset composites. AM is also hindered by process-induced defects such as porosity and unfavorable microstructure. This research shows that a direct write AM process for epoxy / chopped carbon fiber composites can simultaneously achieve a high degree of fiber alignment and low degree of porosity, obtaining 90% of the theoretical tensile modulus and 66% of the theoretical tensile strength for a fully aligned composite. These values exceed those of compression molded properties for the same material. Transverse properties of AM samples were roughly half of the longitudinal properties but showed no statistically significant difference from the matrix material, suggesting that the process may not adversely affect microstructure. The addition of only 5.5 vol% carbon fiber more than doubled the strength and stiffness of the neat epoxy, and more than tripled the properties of ABS thermoplastic while achieving a higher glass transition temperature. Flexural properties show similar trends. SEM and CT imaging shows that fiber orientation is largely maintained in the print direction and cross-section micrographs show there is sufficient local material flow during deposition to achieve low porosity.

Comprehensive modelling, analysis and optimization of furan resin-based moulding sand system with sawdust as an additive

Scarcity of high-cost silica sand, casting defect such as hot tear in hard moulds and casting ejection problem after solidification are the key industrial problems. Sawdust is a by-product of wood working industries, and economic disposal of sawdust in these industries is a growing concern to the wood industries. The present work utilized sawdust as an additive in preparing mould cavity for casting applications. Sand mould properties such as compression strength (CS), mould hardness (MH), gas evolution (GE), permeability (P) and collapsibility (CP) will have good impact on the quality of castings. The effect of variables, namely quantity of resin, hardener, sawdust and setting time, on no-bake furan-bonded sand system is studied in the present research work. The experiments are conducted as per design of experiments, and the data are used to investigate the effect of individual and combined parametric contributions towards responses and establish nonlinear input–output relationships. All nonlinear regression models (that is, input–output relationships) are found to be statistically adequate. The input–output relations are analysed and presented for each of the response with the help of surface plots. Further, the models are found to predict the output close to the experiment (target value). The grand average value in predicting responses is found to be equal to 5.03%. The multi-objective optimization of responses with conflicting nature (minimize: GE and CP; maximize: CS, P and MH) is carried out with the help of global fitness function values determined using genetic algorithm, particle swarm optimization, teacher–learner-based optimization and JAYA algorithms. The optimized values of process parameters that resulted in best set of responses are found to be equal to 60 min, 2.01%, 0.6% and 0.93% for setting time, quantity of resin, hardener and sawdust, respectively. Two automobile coupling parts are cast by pouring molten aluminium into the mould cavity with the optimized and non-optimum sand mould conditions. Further, these two cast components are tested for their quality characteristics, such as surface finish, yield strength, hardness, density and secondary dendrite arm spacing. It has been observed that the quality characteristics of castings produced in mould with optimized parameters are found to be much better.