Cast Parts Research Articles

Optimizing the Gating System for Rapid Investment Casting of Shape Memory Alloys: Computational Numerical Analysis for Defect Minimization in a Simple-Cubic Cell Structure

With the aid of virtual prototyping and casting numerical simulation, this work presents the optimization of an injection system used in a non-traditional investment casting process that applies perpendicular centrifugal force to inject the molten metal into refractory plaster molds. In this study, advanced techniques of simulation and production of complex geometries in Computer-Aided Design CAD (Computer-Aided Design) are used in the design of the casting system of a miniaturized simple-cubic cell structure. The cast part has a complex shape profile and needs a high surface finish with strict dimensional tolerance. The alloy used to fill the mold is an aluminum bronze shape memory alloy (SMA). CAD was used to model the part and the proposed models for casting optimization. ProCAST software was used for the numerical simulation of the casting process. Experimental parameters were used as input data for the numerical simulation. The simulation results were analyzed focusing on the identification of defects in the Cu–Al–Mn SMA simple-cubic structures. Different feeding systems have been designed to eliminate the identified defects. Concerning the molten recirculation, the optimal nozzle model has a truncated cone profile, with a larger radius of 6.5 mm, a smaller radius of 2.0 mm and a height of 8.0 mm (called here model 3). Experimental observations from cast SMA parts agree with the simulated results of the optimized nozzle model 3. In addition to the elimination of alloy recirculation with the nozzle optimization in this work, the shrinkage porosity at the upper base of the part was eliminated with the addition of a compensation volume close to the region where porosity is more intense. By exploring the possibilities offered by commercial software, the work contributes to advance the knowledge and application of the non-traditional investment casting process, highlighting its advantages and potential applications.

Experimental Investigation and Modeling of Force-Induced Surface Errors for the Robot-Assisted Milling Process

A series of experiments were performed aiming at controlling milling force-induced surface errors in the robot-assisted milling process, for the sub-area of the multi-stiffener reinforced inner wall of complex cylindrical thin-walled casting parts, to investigate the relationship between surface errors, milling forces, and robot-assisted milling parameters. Firstly, based on the design of experiments (DoE) method, milling forces and surface errors were investigated based on a series of experiments with different groups of milling parameters. Secondly, the modeling of milling forces, surface errors, and milling parameters was realized by means of response surface methodology (RSM), then the parametric expression was obtained of the robot-assisted milling process. Finally, the parameters of the milling process toward the surface error were obtained based on an evolutionary algorithm. The results show that the surface errors are different for the different milling styles of down milling and up milling. In up milling processes, the surface errors are positive, and the actual material removal amounts are generally higher than the nominal ones, while negative in down milling processes. The surface errors induced by milling forces can be effectively controlled and reduced using process optimization in the robot-assisted milling process, while maintaining relatively high milling forces and high machining efficiency. This provides theoretical support for industry applications.

Nonuniform Distribution of Crystalline Phases and Grain Sizes in the Surface Layers of WC Ceramics Produced by Spark Plasma Sintering

The research results conducted on binderless tungsten carbide (WC) ceramics obtained by spark plasma sintering (SPS) of WC powders with different average particle sizes (95, 800, 3000 nm) are presented. Nonuniform distribution of crystalline phases and microstructure of the WC ceramics was studied using layer-by-layer X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Surface layers of the WC-based ceramics are characterized by nonuniform distribution of W2C crystalline phase and grain sizes, including the appearance of abnormally large grains. Thickness of the nonuniform layer was at least 50 μm. The effect under study is associated with an intense carbon diffusion from graphite foil. On the one hand, this contributed to a decrease in the intensity of W2C phase particle formation, which is transformed into α-WC phase due to the carbon. On the other hand, it caused abnormal grain growth in the layer where the carbon diffused. The obtained value of the carbon diffusion depth (50 μm) exceeds the values known from the literature (up to 1 μm in the case of volume diffusion even at temperature of 2370 °C and exposure time of ~60 h). The use of boron nitride (BN) as a protective coating on graphite mold parts did not prevent the formation of nonuniform layer on the ceramic surface.

Changes in Microstructure and Mechanical Properties of 17-4PH Stainless Steel according to the Application of Laser Rotation in the Powder Bed Fusion(PBF) Process

17-4 precipitation hardened stainless steel (17-4PH SS) has been reported to have excellent mechanical properties and excellent corrosion resistance, and is one of the materials used and studied with the powder bed fusion (PBF) method. Powder bed fusion (PBF) is a new manufacturing technology that has recently attracted attention in automotive, aerospace and other industries because of its ability to produce complex geometries for high-strength and lightweight applications. In the PBF process, each layer has a different laser scan length resulting from the application of laser rotation. The laser rotation could affect the laser scan length, which causes a difference in the peak temperature and cooling rate of the deposited layer, resulting in microstructure changes. This work aims to investigate how varying the laser scan pattern in the PBF process affects the microstructure and mechanical properties of 17-4PH SS. A decrease in cooling rate was observed after applying laser scan rotation, resulting in a higher austenite phase fraction. It was confirmed that a transformation induced plasticity (TRIP) phenomenon affects mechanical characteristics. These results could be suggested for fabricating thin wall shaped such as tire blow mold parts in the powder bed fusion process using the 17-4PH SS.

РАЗРАБОТКИ ПОДПРОГРАММЫ «МЕТАЛЛУРГИЯ», ВЫПОЛНЕННЫЕ В ИНТЕРЕСАХ ПРОМЫШЛЕННЫХ ПРЕДПРИЯТИЙ

The main results of the implementation of the tasks of the subprogram “Metallurgy” of the State Research Program “Mechanics, Metallurgy, Diagnostics in Mechanical Engineering”, 2021–2025, with an applied orientation are presented, which are obtained by the organizations of the National Academy of Sciences of Belarus, the Ministry of Education and the Ministry of Industry of the Republic of Belarus. Their contribution to the solution of practical problems is shown. In the field of metallurgy of iron-carbon alloys, a range of new grades of steels for large gears and large castings of supporting systems of machines are developed. Distinctive features of the developed steels are the possibility to obtain higher hardness values of the hardened layer and teeth of cemented gears compared with counterparts from serial steels. A new sparingly alloyed steel for gearboxes of tractors BELARUS has been developed. The steel is characterized by high hardenability of cemented layer. In the field of metallurgy of non-ferrous metals and alloys, theoretical and technological bases for production of complex configuration castings are developed. Application of these castings improves the dimensional accuracy of products. In the field of hardening of steels and alloys, the technology of coating formation on the working surfaces of metallurgical and foundry equipment parts by mechanical cladding with flexible tool is developed. The coatings provide 1.9 times higher durability of mold parts by compared to the parts without coatings. The technological process of induction cladding on the surfaces of friction nodes parts of wear-resistant antifriction coatings is developed. The service life of bimetallic parts with coatings is 1.25–1.33 times higher than that of serial parts. Physico-chemical principles of creation of aluminomatrix composites were developed on the basis of micro- and ultradispersed oxide powders. This provided a 5-fold increase in tribomechanical properties. In the field of metal forming, the strategy of ring rolling is developed as applied to the nomenclature of rings of the Belarusian enterprises. Technological substantiation is performed for reducing deformations and residual stresses after heat treatment of low-rigid parts such as discs using dynamic stabilization based on alternating cyclic loading.

Water-aluminum reaction by MD simulations and its interpretation defect formation

Many of the aluminum and its alloys are produced by casting methods. During casting, aluminum is heated to temperatures above melting point. In the liquid state, aluminum reacts with water vapor to form aluminum oxide on the surface and hydrogen is dissolved in the melt. These are the two most critical defects that deteriorate the properties of the cast part. Therefore, it is important to investigate the possible reactions of water vapor with liquid aluminum in order to understand the formation of these defects. In this work, Molecular Dynamic (MD) analysis was used to evaluate the reactions of water vapor with aluminum at various temperatures (300, 500, 700, 900 and 1100 K). It was found that when aluminum reacts with water vapor, aluminum oxide layers form on the surface of the aluminum block. In addition, mono and di-atomic hydrogen are released due to the reaction between aluminum and water. These free hydrogen atoms are distributed homogeneously and rapidly in the aluminum block and gap between two aluminum blocks.

Effects of L-PBF Scanning Strategy and Sloping Angle on the Process Properties of TC11 Titanium Alloy

TC11 titanium alloy is widely used in aerospace. To investigate the production of TC11 titanium alloy parts of high quality and performance, this paper adopts the Laser powder bed fusion (L-PBF) technique to prepare TC11 alloy specimens. We analyze in detail the effects of scanning strategy and forming angle on the forming quality and performance of TC11 alloy through a combination of theory and experiment. The results show that the upper surface quality of the strip-scanned molded parts is the highest, and the upper surface quality is better than that of the side surface under different scanning strategies. The fusion channel lap and surface adhesion powder were the main factors affecting the surface roughness. With increases in the forming angle, the surface roughness of the overhanging surface gradually decreases and the hardness gradually increases. The surface quality and hardness of the specimen are optimal when the forming angle is 90°. The research results provide the theoretical basis and technical support for L-PBF forming of TC11 titanium alloy parts.

Interactive mold design for paediatric lower airway manikin manufacturing: a feasibility study

According to previous research, shore 40 A casting silicone is currently one of the more suitable materials for simulating the physical behavior of the airways in medicine simulation. This is essential to attain high-fidelity manikins that can perfectly mimic the simulated anatomic region, not just geometrically, but also in terms of haptic feedback. Due to the geometrical complexity of the tracheo-bronchial tree, mold design is a difficult and time-consuming process. An interactive modeling procedure for modeling mold parts for tracheo-bronchial tree casting is proposed in this paper, with the purpose of reducing modeling time without compromising quality. Following the definition of a standard modeling procedure, this was implemented in the Matlab language by using an IGES and STL editing toolbox. By using the interactive procedure it is possible to reduce the time required for virtual modeling from several hours to less than 1 min. Given this preliminary result, the proposed procedure will be further tested and developed in the near future, with the possibility of automating other lower airway modeling steps, such as vent generation and mounting holes/pins.

Strength-plasticity transition mechanism after the solution treatment of GH3230 superalloy fabricated via laser powder bed fusion

Owing to their unique microstructure, GH3230 superalloys prepared using laser powder bed fusion (LPBF) exhibit high strength but low ductility, which limits their functional performance in engine combustion chambers. In this study, the process parameters were optimized to obtain LPBF GH3230 with minimal defects, and solid-solution treatment (ST) was conducted to modulate its inhomogeneous microstructure and mechanical properties. The results revealed that ST eliminated the substructure of as-printed (AP) samples and transformed nano-M23C6 into micron and submicron M6C/M12C in situ. Significant amounts of M6C/M12C promoted Orowan strengthening, but the quasi-continuous semi-coherent lattice interface between M6C/M12C and the matrix was a weak zone for cracking, resulting in reduced plasticity owing to the presence of micron carbide. The increased solid solution temperature causes the carbide to remelt, triggering a strong plastic transformation. The impact of carbide size on strength and plasticity conversion rate was more significant than that of carbide content. Final, LPBF-GH3230 samples containing micron carbides were obtained in ST below 1230 °C with an ultimate tensile strength (UTS) comparable to that of forgings. Further increase in the ST temperature to 1280 °C eliminated the carbides, a LPBF-GH3230 that fulfilled the strength standard for cast parts (647 ± 23 MPa) with an excellent elongation (39.4 ± 1.7%) was obtained. This study provides a theoretical basis for the practical application of the LPBF GH3230 superalloy in the aerospace industry and offers guidance for improving post-treatment methods to ensure high plasticity.

Synthesis and characterization of stereolithography3Dprinting fluorescent resin

AbstractIn this study, bisphenol A epoxy resin, 1,6‐Hexanediol diacrylate (HDDA), and 2,4,6‐Trimethylbenzoyl‐diphenylphosphine oxide (TPO) were utilized as a prepolymer, diluent, and photoinitiator, respectively, to prepare a light curing system with different amount of phosphor, which was used in place of conventional inorganic fillers. Phosphor was utilized to improve the precision of the material molded parts during the light curing process and enhance the mechanical properties of the molded parts owing to the ultraviolet (UV) absorption properties of phosphor, which prevented UV damage to the material, thus improving the light aging resistance and stability of the molded parts. Results revealed that the addition of 3% phosphor optimized the mechanical properties of the material (a maximum tensile strength of 42.43 MPa). Additionally, the material achieved the lowest linear (4.1%) and volumetric (0.58%) shrinkage at a phosphor content of 6%. This study provides a new insight into three‐dimensional (3D) printing resin for stereolithography and provides a reference for the improvement of 3D printing products.

Optimisation of melt pouring temperature and low superheat casting of Al-15Mg2Si-4.5Si composite

ABSTRACT In this study, a computational fluid dynamics (CFD) model is employed to optimise the melt pouring temperature during Low superheat casting (LSC) of the Al-15 Mg2Si-4.5Si composite. The die cavity considered to perform the die filling simulations corresponds to the as-cast tensile specimens, as per ASTM B557 guidelines. The findings of the study include melt temperature distribution, solid fraction distribution during filling as well as during solidification, velocity distribution of the melt and surface defect concentration. Experimentation is performed to develop low superheat cast composite based on the numerically estimated optimum melt pouring temperature of 650°C. Mixture of irregular dendritic, polygonal and equiaxed shaped primary Mg2Si grains are observed within the cast parts, whereas primary Al grains are found to be of dendritic morphology with occasional presence of spheroids. Marked improvements in microstructure and mechanical properties have been evidenced in the LSC composite compared to its conventional cast counterpart.

Effect of melt-to-solid volume ratio and preheating temperature on Mg/Al bimetals interface by centrifugal casting

Compound casting is an efficient method for bonding dissimilar metals, in which a dramatic reaction can occur between the melt and solid. The centrifugal casting process, a type of compound casting, was applied to cast Al/Mg dissimilar bimetals. Magnesium melt was poured at 700°C, with melt-to-solid volume ratios (Vm/Vs) of 1.5 and 3, into a preheated hollow aluminum cylinder. The preheating temperatures of the solid part were 320, 400, and 450°C, and the constant rotational speed was 1,600 rpm. The cast parts were kept inside the casting machine until reaching the cooling temperature of 150°C. The result showed that an increase in preheating temperature from 320 to 450°C led to an enhanced reaction layer thickness. In addition, an increase in the Vm/Vs from 1.5 to 3 resulted in raising the interface thickness from 1.2 to 1.8 mm. Moreover, the interface was not continuously formed when a Vm/Vs of 3 was selected. In this case, the force of contraction overcame the resultant acting force on the interface. An interface formed at the volume ratio of 1.5 was examined using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), and the results demonstrated the formation of Al3Mg2, Al12Mg17 and (δ+Al12Mg17) eutectic structures in the interface.

Simulation Study on Microstructure of Magnetic Field Assisted ECAM

Electrochemical additive manufacturing (ECAM) technology is a non-thermal metal additive manufacturing technology that is widely used in microfabrication. The quality of additively manufactured moulded parts can be improved by applying magnetic fields with unknown effects of process parameters on additively manufactured microstructures. Therefore, a multi-physical field coupling model for magnetic field-assisted ECAM was developed. The results show that increasing the applied voltage and magnetic field strength can increase the cathode current density and improve the deposition rate and deposition height, but after the applied voltage increases to 4 V, the ion concentration decreases too fast and the concentration polarization occurs, which affects the deposition rate instead. The ion flux reached the maximum at the magnetic field strength of 0.2T. However, the cathode current density is affected by the electrode gap, and the deposition rate decreases with the increase of the electrode gap, and the deposition rate stabilizes after the electrode gap increases to 50 μm. The increase in current density with increasing electrode size may be related to the applied magnetic field.

Combined defect prediction for large-area die-cast components using high-resolution multi-phase simulation

In the automotive industry there is a trend towards large components that are manufactured using high pressure die casting process (HPDC), in particular when many previously welded individual parts are to be replaced with one cast part to save costs and energy. In the case of large components, incipient solidification during mold filling cannot be ruled out. Casting defects due to cold running, air pockets and porosity cannot be separated spatially and temporally and influence each other. This stronger linking of the defects requires a realistic depiction of the casting process in the simulation, since the interactions between effects are more difficult to depict through approximations. The multi-phase approach presented here offers various options for this: The air is calculated as a compressible gas that is separated from the melt by a sharp boundary surface. Reduced melt flow due to solidification is represented by a porous media approach, followed by a complete flow stop at high solids. The formation of porosity due to volume shrinkage is coupled with a gas evaporation model. The multi-phase approach was validated by casting trials using a specially designed test geometry for thin-walled aluminum HPDC applications. First results of an industrial application are shown.

Improving technology for manufacturing casting case of truck clutch release cylinder

The object of research: Manufacturing technology of body castings for trucks using the example of a clutch release cylinder body made of gray cast iron with flake graphite EN-GJL-200.
 Investigated problem: Finding ways to reduce the weight and size characteristics of cast parts.
 The main scientific results: A mathematical model has been developed that has made it possible to determine the optimal compositions of alloying Cr/Ni – Cu/Ti complexes that ensure an increase in the grade of cast iron by increasing the tensile strength at elevated carbon contents. This makes it possible in the future to reduce the thickness of the walls of the castings, achieving a reduction in their weight and size characteristics
 The area of practical use of the results of the study: Automotive industry in terms of technology for manufacturing cast parts for trucks
 Innovative technological product: Improved technology for manufacturing the clutch release cylinder body due to optimization of melt technology and out-of-furnace processing allows for targeted selection of melt processing modes, ensuring an increase in the strength characteristics of cast iron for cast body parts, thereby moving from the EN-GJL-200 cast iron grade to the EN grade -GJL-250 and EN-GJL-300.
 The scope of the innovative technological product: Foundries of engineering enterprises, in particular those producing trucks, in which iron castings are produced

Analysis of the slurry and ceramic properties for investment casting obtained with domestic colloidal silica binders

The quality of cast parts produced by investment casting is largely determined by the quality of the ceramic molds. Currently, aircraft and engine building enterprises are switching to an environmentally friendly colloidal silica binders for the manufacture of ceramic molds. In this work, the dynamic and relative viscosity of slurries prepared using fused silica powder and colloidal silica binders of the VT13-02U (Vakuumteh LLC), Stavroform VS (Polymet LLC), UltraCast One + and UltraCast Prime (both Technopark LLC) manufacturers were determined. It is shown that the slurries prepared on the considered binders have similar viscosity values, and in their rheological properties they are close to Newtonian liquids. The values of dynamic and relative viscosity at a binder content of 400 mL per 1 kg of fused silica powder were ~732 mPa·s and ~380 s, respectively. With an increase in the binder content to 600 mL per 1 kg of fused silica powder, the dynamic and relative viscosity decreased to ~70 mPa·s and ~16 s, respectively. An equation was also found that relates the dynamic viscosity determined using a rotational viscometer and the relative viscosity determined using the VZ-4 viscosimeter. The mechanical properties were determined during three-point bending tests on ceramic samples obtained using slurries on the above-mentioned colloidal silica binders and fused silica stucco. Samples obtained on binders VT13-02U, Stavroform VS and UltraCast One+ showed very similar bending strength values, namely 3.5–4.3 MPa after drying and 5.8–6.1 MPa after firing. Due to the presence of a polymer addition in the binder, the ceramic samples obtained on the UltraCast Prime binder had higher values of bending strength after drying and after firing – 6.4 and 7.2 MPa, respectively. It was also shown that with an increase in the viscosity of the slurry and a decrease in the fraction of fused silica stucco, the strength of the samples increases. The lowest surface roughness was observed for samples obtained with UltraCast grade binders.

A Machine Learning Approach for Automated Cost Estimation of Plastic Injection Molding Parts

Market competition leads to shorter cycle times for new or updated products. Therefore, flexibility in reacting to market changes, product development, and all related processes must be accelerated. In this regard, accurate cost estimation in the early stages of product development is critical for assessing the economic viability of a product. However, cost estimation requires data and expertise from several departments. Machine learning approaches could improve the accuracy and reduce the time needed for cost estimation. To investigate the eligibility of machine learning based cost estimation, a case study was conducted on an industrial company that produces plastic molding parts as key components of its products. The study involved training various supervised machine learning algorithms on a dataset of plastic injection molding parts using three different cost calculation methods. The three methods differed in the extent to which they considered the different process steps involved in the production of the parts. Different tree-based machine learning regression models and neural network models were trained to identify the most suitable approach for cost estimation in the given context. The results showed that tree-based machine learning algorithms outperformed neural networks and that individually predicting manufacturing parameters for cost calculation of each manufacturing process step leads to the most accurate cost estimation. This paper demonstrates how machine learning can support cost estimation in the early stages of the product lifecycle, reducing development times and improving cost estimation accuracy.

Assessing Cast Aluminum Alloys with Computed Tomography Defect Metrics: A Gurson Porous Plasticity Approach

Aluminum alloys have inherent tendencies to produce casting defects caused by alloying or metal melt flow inside the mold. The traditional detection method for these defects includes reduced pressure tests, which assess metal quality in a destructive manner. This leaves a gap between metal quality assessments and tensile test correlations. Computed tomography (CT) scans offer crucial assistance in evaluating the internal quality of castings without damaging the structure. This provides a valuable opportunity to couple mechanical tests with numerical methods such as finite element analysis to predict the mechanical performance of the alloy. The present study aims to evaluate the internal quality of cast aluminum alloys using CT scans and to correlate the defect metrics obtained from CT scans with mechanical test results. The Gurson-type material model and finite element methodology have been used to validate the correlation studies. Therefore, we propose a more holistic approach to predicting the behavior of metals by coupling damage models with CT scans and mechanical tests. The study investigates several CT metrics such as the defect volume, total defect surface, biggest defect surface, and projected area of defects. The conclusion reveals that CT scans provide crucial assistance in evaluating the internal quality of castings, and CT defect metrics can be used to build correlations between mechanical tests and CT evaluations. The study also suggests that the concept of adjusted representative material yield parameter (ARMY) or computed representative material yield parameter (CRMY) can be used to correlate CT metrics with mechanical strength in cast materials and parts for a given aluminum alloy. Overall, the study proposes a more comprehensive methodology to assess the quality of cast aluminum alloys and couple the quality to mechanical performance.

Ex-Ante Eco-Efficiency Assessment of Dendromass Production: Conception and Experiences of an Innovation Project

Rising demand for bio-based products exerts growing pressure on natural resources such as wood. The agricultural technique of short rotation coppice (SRC) to produce dendromass from fast growing trees has gained relevance to ease the pressure of demand for wood from forests. The European-funded project Dendromass4Europe supports the establishment of SRC in Western Slovakia and its biomass use for four new bio-based materials, in the context of a developing bioeconomy. Along with the development of the SRC and material value chains, eco-efficiency assessment is carried out to anticipate areas of critical concern and derive measures for improvement. Among many other assessment approaches, eco-efficiency assessment was conducted by combining Life Cycle Assessment (LCA) and socio-economic assessment to optimize the whole production system towards eco-efficiency. An LCA study provided necessary data to assess the environmental performance. The added value and revenue results from the socio-economic assessment were used to assess the economic performance. The value chain of the moulded fibre parts shows the best eco-efficiency value, but only because its economic performance is comparatively strong. The lightweight boards have the least environmental impact but do not perform so well in terms of eco-efficiency. The overall eco-efficiency of the full value chain can be optimized only with a specific combination of all four dendromass-based materials within the whole production system.

Experimental Analysis on Polypropylene Moulded Part for Performance of Laser Printing

Now a day plastic injection molding is widely used process to manufacture engineering product and consumer goods typically thermoplastic is combined with rubber or another thermoplastic like RM master batch is used to add color to the Molded part also the laser marking on plastic part and their printing cut, faint issue observed. The aim of the study was to Optimize the injection parameters and processing condition for the laser performance on polypropylene part. To achieve enhanced dark laser marking on polypropylene, the process parameter of plastic injection molding and the Raw material master batch mixing parameter successfully prepared this laser–sensitive composite consisted of a high Laser induced carbonization rate.in plastic injection molding use of raw material and mixing of master batch is considerable factor for faint laser marking. Because of laser does not respond well on carbonization added material, it was evident that master batch having the carbon properties is much more responsible for faint laser marking issue on polypropylene material part. The effect of laser beam interaction (Nd: YVO4) with selected operational parameters on the Quality of graphical features obtained on the surface of polypropylene-molded pieces with different surface Textures (variable parameters of the surface layer). Polypropylene test specimens were injection molded using original injection molds Products with variable end parameters determined by the position of the cavity circle can be identified. The layout of the laser function, the beneficiary texture of the molded piece, the molded color and the support of the marking piece allow the evaluation of the graphic symbol performance by means of laser marking of the type of master back in their rendering relationship. Marked evaluation criteria were adopted for the project.