Low-pressure Casting Research Articles

A novel nonlinear pressurization method for counter-gravity casting of cross-sectional mutation structures

In order to ensure the filling integrity of complex counter-gravity casting and improve metallurgical quality, it is necessary to shorten the filling time while avoiding air entrainments. To address this contradiction, a novel nonlinear pressurization method was proposed in this study. Through systematically analyzing the relationship between critical gating velocity and stable filling height, a criterion for iterative calculation of nonlinear pressurization curve was established, and an empirical expression between nonlinear pressurizing speed and the filling height was obtained. Based on the empirical expression, a nonlinear pressurization curve can be designed according to the casting structures and initial pressurizing speeds. The above nonlinear pressure curve design method was validated through water filling experiments. It was proved that the nonlinear pressure curve can shorten the filling time while avoiding air entrainments. It provides important processing control method for improving the low-pressure casting performance of complex castings.

Adaptive neuro-fuzzy inference system approach for tensile properties prediction of LPDC A357 aluminum alloy

This study is based on the desire of aluminum casting foundries to understand the influence of minor changes, within the specification limits, in the alloy chemistry. In order to ensure the casting of A357 Al alloys within the framework of the casting standards and to minimize the quality problems that may arise during casting; the estimation of ultimate tensile strength (UTS), yield strength (YS) and elongation (ε) due to very small changes among the alloying elements, although they are in the standard range, by using machine learning method (ML), were studied. The dataset of chemical composition and tensile properties of Low-Pressure Die Cast (LPDC) A357 Al alloy were experimentally established. The relationship between five input variables in the A357 alloy, namely the main alloying elements Si and Mg together with the most common impurity contents Fe, Ti and Cu were selected and three outputs (i.e UTS, YS and ε) were linked by Adaptive Neuro Fuzzy Inference System (ANFIS). The ANFIS model predicted that the most detrimental element affecting tensile properties was Fe content. According to this model, the order of the relative importance on UTS, YS and ε revealed as Si, Mg and Ti content respectively after the Fe content of the alloy.

Revealing the Relationship between Critical Inlet Velocity and a Double-Layer Oxide Film Combined with Low-Pressure Casting Technology

In the context of low-pressure casting, an excessive inlet velocity may result in the introduction of an oxide film and air into a liquid metal, leading to the formation of a two-layer film structure within the casting. Such defects can significantly degrade the mechanical properties of the castings. In order to optimize the advantages of low-pressure casting, an empirically designed equation for the inlet velocity was formulated and the concept of critical inlet velocity was further refined. A comprehensive numerical simulation was conducted to meticulously analyze the liquid metal spreading phase within the cavity. Subsequently, low-pressure casting experiments were carried out with actual castings of an A357 alloy, using two different entrance velocities—one critical and the other exceeding the critical entrance velocity. Tensile test specimens were extracted from the castings for the comparative evaluation of mechanical properties. It was observed that the average tensile strength of specimens cast at the critical inlet velocity exhibited a notable 16% enhancement. In contrast, specimens cast at velocities exceeding the critical inlet velocity manifested the presence of double oxide film defects. This evidence suggests that casting at a velocity faster than the critical inlet velocity leads to the formation of double oxide film defects, which in turn reduces the mechanical properties of the castings.

The Potential of Cast Stock for the Forging of Aluminum Components within the Automotive Industry

In the automotive industry, there is a drive to reduce environmental impact, energy consumption, and costs related to the manufacturing of forged aluminum suspension components. The replacement of extruded stock with cast forging stock is one option that offers substantial potential for such savings. The casting technology, low-pressure casting (LPC), allows for production of high-quality cast forging stock with minimal surface segregation and smaller diameters than those achieved with traditional casting technologies. This study is a proof-of-principle, conducted to directly compare the microstructure and mechanical properties of LPC and extruded material after forging, through both generic and full-scale industrial forging trials. The results show the advantages of the cast material, including higher robustness against surface grain growth after forging and a positive correlation between mechanical properties, both strength and ductility and the introduction of plastic deformation. Overall, the work demonstrates how forged aluminum components produced from LPC forging stock can achieve mechanical properties and performance, on par with extruded forging stock, showcasing industrial relevance through the production of a safety-critical automotive component.

Optimization of Process Parameters for Machining of Steel Molds used for Aluminum Casting in Wheel Industry

The wheel industry, employing low-pressure casting techniques for producing lightweight alloy wheels, operates within a highly competitive manufacturing environment with significant production volumes. To fabricate essential mold core components for the aluminum wheel casting process, hot work tool steel alloys are selected for their exceptional durability and resistance to wear, fatigue, distortion, and high-temperature plastic deformation. Efficient machining operations for these steel molds require identifying optimal parameter combinations to minimize tool wear, surface roughness, and energy consumption while maximizing material removal rates. This study focuses on determining such parameters, utilizing DIN 1.2367 steel, to enhance manufacturing efficiency and meet industry requirements. The effects of machining parameters such as cutting speed, depth of cut, and number of inserts were investigated using the design of experiments. Depth of cut was determined as the most influential factor on tool wear, revealing the optimum parameter as 0.4 mm, followed by cutting speed. Notably, the number of inserts exhibits minimal direct impact but interacts significantly with the depth of cut, influencing wear patterns. This research contributes to sustainable machining practices by enhancing mold core manufacturing efficiency, prolonging tool life, and reducing tool wear. Such advancements are vital for the long-term competitiveness and environmental stewardship of the wheel industry.

Multi-Objective Optimization of The Low-Pressure Casting of Large-Size Aluminum Alloy Wheels through a Systematic Optimization Idea.

The process parameters in the low-pressure casting of large-size aluminum alloy wheels are systematically optimized in this work using numerical casting simulation, response surface methodology (RSM), and genetic algorithm (NSGA-II). A nonlinear input-output relationship was established based on the Box-Behnken experimental design (BBD) for the crucial casting parameters (pouring temperature, mold temperature, holding pressure, holding time), and response indicators (defect volume fraction, spokes large plane mean secondary dendrite spacing (SDAS)), and a mathematical model was developed by regression analysis. The Isight 2017 Design Gateway and NSGA-II algorithm were used to increase the population and look for the best overall solution for the casting parameters. The significance and predictive power of the model were assessed using ANOVA. Casting numerical simulation was used to confirm the best option. To accomplish systematic optimization in its low-pressure casting process, the mold cooling process parameters were adjusted following the local solidification rate. The results showed that the mathematical model was reliable. The optimal solutions were a pouring temperature of 703 °C, mold temperature of 409 °C, holding pressure of 1086 mb, and holding time of 249 s. The mold cooling process was further optimized, and the sequence solidification of the optimal solution was realized under the optimized cooling process. Finally, the wheel hub was manufactured on a trial basis. The X-ray detection, mechanical property analysis, and metallographic observation showed that the wheel hub had no X-ray defects and its mechanical properties were well strengthened. The effectiveness of the system optimization process scheme was verified.

Optimization of residual stress in low-pressure casting of ZL205A alloys

ZL205A alloys are prone to generate serious residual stress due to the long solidification intervals and multi-phase composition. In this study, the low-pressure casting process for ZL205A alloy hemisphere shell casting was investigated and continuously optimized. In the initial process, the knockout time, pouring temperature, preheating temperature of the sand mould, dwelling pressure, and filling rate were 3 h, 710 °C, 30 °C, 65 kPa, and 0.33 kPa·s−1, respectively. Macroscopic properties and microstructural features were simulated using a combination of ProCAST and Thermal-Calc software. Additionally, a series of experimental procedures, including EBSD, SEM, EDS, and XRD tests, were conducted to investigate the formation, morphology, and distribution of the microstructure. Current findings demonstrate that during the solidification process, the maximum temperature difference exceeds 220 °C, the maximum undercooling reaches 49.56 °C, and the maximum effective stress peaks at 301.7 MPa. The residual stress ranges from 20 to 200 MPa. Furthermore, there is no significant texture and preferred grain orientation during nucleation and solidification, and the structure field exhibits an equiaxed crystal but inhomogeneous pattern. Moreover, the finer and more homogeneous the grains and the smaller the deviation in grain orientation, the lower the residual stress. Specifically, two analytical models are developed: one between the casting parameters and the residual stress, and another between the shrinkage defects and the casting parameters. The lowest residual stress is achieved when the knockout time, pouring temperature, preheating temperature of the sand mould, dwelling pressure, and filling rate are 6 h, 725 °C, 250 °C, 95 kPa, and 1.67 kPa·s−1 respectively.

Hot Tearing Behavior of ZL205A Alloy Cylindrical Low-Pressure Castings with Slit Gating and Feeding System

Hot Tearing Behavior of ZL205A Alloy Cylindrical Low-Pressure Castings with Slit Gating and Feeding System

ELASTOMERIC POLYMER COMPOUNDS FOR PRODUCTION OF SPARE PARTS FOR ROBOTIC MILKING SYSTEM

Currently, the import of spare parts of systems, in particular, nipple rubber and elastomeric parts of the milk pump of the milking unit, has been discontinued. In this regard, the problem of developing technologies for manufacturing elastomeric spare parts for milking machines becomes urgent. One of the possible ways of cost-effective production of spare parts in conditions of small-scale production is free casting or low-pressure casting. To implement such technologies, materials with low viscosity (less than 50 pascals per second) are needed, which include polymer compounds. (Research purpose) The research purpose is determining the brands of elastomeric polymer compounds suitable for the manufacture of spare parts for milking machines. (Materials and methods) Used scientific and technical literature as materials for studying, including articles of indexed periodicals and open sources of information containing information about elastomeric polymer compounds. Research methods are the collection, study and comparative analysis of information. (Results and discussion) It was found that among all polymer compounds, epoxy, polyester, polyurethane and silicone compounds were the most widespread in mechanical engineering and the food industry. It was determined that compounds based on polyurethane or silicone are the most suitable for the manufacture of spare parts for milking machines. These materials provide sufficient mechanical characteristics and high elasticity of the manufactured part. It was noted that silicone-based compounds are used for food purposes, which ensures the chemical and biological inertia of the part. (Conclusions) The most suitable brands of elastomeric silicone compounds are Elastolux Platinum 40 and Silagerm 8040. These materials are manufactured in Russia, have low shrinkage, provide high strength and elasticity of the final parts.

Research on the low-pressure casting process of a double suction impeller in 304 austenitic stainless steel with high performance and thin-wall complex structure

The manufacturing of thin-wall complex castings using pressure-assisted casting is one of the most significant challenges for structural applications requiring excellent mechanical properties and fuel. In this paper, efforts have been made to manufacture thin-wall complex structure casting using high-temperature alloys with high strength. Low pressure casting forming process was used to manufacture a double suction impeller in 304 austenitic stainless steel with a thin-wall complex structure. By combining 3D printed sand mold with an optimized low-pressure casting process, a double suction impeller with a thin-wall thickness of 3mm was successfully prepared. The prepared double suction impeller showed structural integrity, smooth surface, and compact structure. The filling and solidification process of the 304 austenitic stainless-steel melts were analyzed using casting simulation software. The casting had an excellent mechanical property with a tensile strength of 595 MPa, yield strength of 265 MPa, and elongation of 48%. Results show that the improved low-pressure casting processes could be applied to the production of thin-wall complex structure parts during high-temperature casting processes. The results are of great significance to the casting of high-temperature alloys.

Mechanical Wave Propagation in Solidifying Al-Cu-Mn-Ti Alloy and Its Effect on Solidification Feeding

The wave field in solidifying metals is the theoretical basis for analyzing the effects of mechanical vibration on solidification, but there is little research on this topic. This study investigated the wave field and its effect on the solidification feeding in the low-pressure sand casting (LPSC) of Al-Cu-Mn-Ti alloy through experimental and numerical investigation. The solidification temperature field was simulated by AnycastingTM, and the wave field was simulated by the self-developed wave propagation software. The shrinkage defect detection showed that applying vibration had a greater promotional effect on feeding than increasing the holding pressure. The predicted defects under vibration coincided with the detections. The displacement field showed that the casting vibrated harmonically with an inhomogeneous amplitude distribution under the continuous harmonic vibration excitation, and the vibration energy was mainly concentrated in the feeding channel. With solidification, the ux amplitude reduced rapidly after the overlapping of dendrites, finally reducing slowly to a certain level; the uy amplitude reduced dramatically after the occurrence of a quasi-solid phase, finally reducing slowly to near zero. Mechanical vibration produced a severe shear deformation in the quasi-liquid phase—especially in the lower feeding channel—reducing the grain size to promote mass feeding. The feeding pressure and feeding gap were changed periodically under vibration, causing the vibration-promoting interdendritic feeding rate to fluctuate and eventually stabilize at about 13.4%. The mechanical vibration can increase the feeding pressure difference and change the blockage structure simultaneously, increasing the formation probability of burst feeding.

Effect of Mechanical Vibration on the Mechanical Properties and Solidification Feeding in Low-Pressure Sand Casting of Al-Cu-Mn-Ti Alloy.

The shrinkage defects of Al-Cu-Mn-Ti alloy seriously hinder its application in high-performance engineering. In this study, mechanical vibration was introduced to low-pressure sand casting (LPSC) by a waveguide rod to eliminate shrinkage defects and improve mechanical properties. Four LPSC castings were performed by changing the solidification conditions: 20 kPa solidification pressure without and with 14 Hz vibration and 40 kPa without and with 24 Hz (the natural frequency of a casting system) vibration. The shrinkage defects, microstructures, and mechanical tensile properties at room temperature and at 2 mm/min tensile rate were investigated. X-ray detections showed that applying vibration was more effective than increasing solidification pressure in improving solidification feeding, while the most effective method was applying both simultaneously, which eliminated the shrinkage defects and increased the density by 2.7%. Microstructures exhibited that the average size of primary α-Al grains were reduced by 29.5%; mechanical tests showed that the ultimate tensile strength and the elongation increased by 21.7% and 7.8%, respectively, by applying vibration and increasing the solidification pressure simultaneously, as compared to the casting with 20 kPa solidification pressure without vibration. Mechanical vibration was conducive to mass feeding by refining the primary grains, to interdendritic feeding by reducing the threshold pressure gradient, and to burst feeding by collapsing the barrier.

Microstructure and high-temperature mechanical properties of new-type heat-resisting aluminum alloy Al6.5Cu2Ni0.5Zr0.3Ti0.25V under the T7 condition

Making use of the low-pressure sand mold casting preparation Al6.5Cu2Ni0.5Zr0.3Ti0.25V alloy. After T7 heat treatment, microstructure observation shows that the average grain size of the Al matrix is 150 μm, and the second phase is θ'-Al2Cu, Al7Cu4Ni, Al3M (M = Ti, Zr, V). The tensile strength is 127.5 MPa, the yield strength is 108Mpa, and the elongation is 16.11 %. The θ'-Al2Cu phase in the grain, a small amount of Al3M (M = Ti, Zr, V) thermal stable phase, and the Al7Cu4Ni phase at the grain boundary make the alloy exhibit excellent high-temperature mechanical properties at 350℃.

Microstructure and mechanical properties of LPSC AZ91-Sb magnesium alloy

ABSTRACT Microstructures and mechanical properties of AZ91-Sb magnesium alloy fabricated by low-pressure shell casting (LPSC) process in different conditions were investigated. The as-cast alloy exhibited a good internal quality and denser structure. The microstructure of α-Mg phases displayed dendritic feature and fine isolated β-Mg17Al12 particles phases uniformly distributed in the matrix. After the solution treatment at 415°C for 12 h, almost β-Mg17Al12 phases dissolved into the matrix. After ageing treatment at 200°C for 14 h, the LPSC alloy attained the peak hardness with restrained age-hardening kinetics. The discontinuous precipitates initiated at the grain boundaries and then continuous precipitates occurred in the grain interior. The LPSC alloy exhibits higher mechanical properties in both as-cast and heat-treated alloys compared with the gravity casting (GC) process alloy.

Key Analysis of Design and Numerical Simulation for Aluminum Alloy Impeller Low-pressure Casting Mold

It is of great practical value to complete the low-pressure casting of aluminum alloy impeller in the current development of low-pressure casting process. In the research, it is necessary to focus on factory realization and use low-pressure casting to produce aluminum alloy impellers, so that impeller castings with compact structure and meeting performance requirements can be obtained. Compared with other casting methods, low-pressure casting itself, as a precision casting method, can be cast on the metal solution with lower pressure in the application process. The castings can be filled and solidified under certain pressure, and the castings with compact structure can be obtained. In the research, Pro / Engineer is used to design the low-pressure casting mold for aluminum alloy impeller, and MAGMASOFT is used to carry out the filling and solidification process of aluminum alloy impeller. Through numerical simulation, we can accurately predict the defects of impeller castings, and optimize the mold scheme and pressure-time parameters according to the prediction results.

Alloy development and process innovations for light metals casting

The combination of light metals (aluminum, magnesium and titanium) and innovative casting processes provides cost-effective technologies to produce lightweight components and systems for many industrial applications. This article provides a comprehensive and yet critical review of light alloy development for cast components used in lightweight and high-performance structural and propulsion applications. It also summarized some latest process innovations in gravity casting, high pressure die casting, and low pressure casting, to overcome some fundamental issues related to defect formation in casting processes. Emerging casting processes developed in the last twenty years, such as semisolid processing, squeeze casting, ablation casting, bimetallic overcasting, and diffusion solidification processing, are discussed for further development. Recent advances in casting simulation and the concept of Integrated Computational Materials Engineering (ICME) are summarized for casting applications. Finally, future perspectives in light alloy development (including green alloys, high entropy alloys and metal matric composites), process innovations (such as high integrity casting, multi-material manufacturing and additive manufacturing), and ICME development are presented to stimulate further research and sustainable development in this important field of metals processing technology.

Prediction of mechanical properties of ZL702A based on neural network and regression analysis

The quantile regression neural network (QRNN) has shown high potential for predicting the mechanical properties of the alloy. The QRNN model and the regression model were developed to predict the mechanical properties of the low-pressure cast aluminum alloy ZL702A using the mechanical properties, the temperature, and the microstructure data, and the prediction accuracies of the two prediction models were compared in this article. The regression model predicted better for the screened data, while the QRNN model predicted better for the unscreened data. Finally, the evolution characteristics of the microstructure with temperature are analyzed, and it is found that the changes of SDAS and composition with temperature are the main reasons for the changes of material properties with temperature. After the analysis and comparison, it is determined that the QRNN model predicts the mechanical properties more concisely and accurately.

Transfer Ladle Tracking System Using Wireless Sensor Network

Process optimization is one of the most important steps in improvement. Data need to be collected and evaluated to improve a process, reduce non-value-added time and make the process more efficient. Within the scope of the study, the foundry of a company that produces passenger car wheels using low pressure casting method is theoretically modified with a sensor network containing RFID and ZigBee, thermocouple and wireless forklift scale. Problems that may be encountered while establishing the sensor network are anticipated and solution suggestions are presented.

Comparative Study on the Corrosion Resistance of 6061Al and SiC3D/6061Al Composite in a Chloride Environment.

Interface problems and the destruction of the continuity of the oxide film in the Al matrix usually reduce the corrosion resistance of the material. In this paper, the corrosion resistance of Al matrix composites (AMCs) was improved by introducing the silicon carbide skeletons (SiC3D) obtained with polymer replica technology. SiC3D/6061Al was fabricated by infiltrating molten 6061Al alloy in the oxidized SiC3D using the low-pressure casting method. The corrosion resistance performances of 6061Al and SiC3D/6061Al in NaCl solution were studied by electrochemical, neutral salt spray corrosion (NSS), and salt leaching (SL) tests. Results show corrosion resistance of SiC3D/6061Al is higher than that of 6061Al alloys by open circuit potential (OCP), potentio-dynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) tests. However, NSS and SL tests show the corrosion resistance of SiC3D/6061Al is lower than that of 6061Al alloy. The reason is a corrosion resistant and anti-oxidation network macrostructure with large interface recombination, few concentrated interfaces, and a small specific area that formed in SiC3D/6061Al. SiC3D cannot damage the continuity of the Al2O3 passivating film, and the network macrostructure greatly improves the corrosion resistance performance.

Effects of different holding pressures on the microstructure and mechanical properties of Al-5.9Zn-2.2Mg-1.8Cu alloy

In this study, a low-pressure casting process was used to examine the influence of the holding pressure on the Al–5.9Zn–2.2Mg–1.8Cu alloy. The study aimed to refine the grain structure and optimize the microstructural homogeneity and mechanical properties of the alloy. The phase composition, microstructure, chemical composition, and fracture morphology of the alloy were determined using optical microscopy, SEM, inductively coupled plasma spectroscopy, and XRD. As the holding pressure increased, the theoretical crystallisation temperature of the alloy increased, which increased the degree of undercooling during solidification and the effective number of nuclei, resulting in grain refinement. In addition, increase in the holding pressure strengthened the feeding ability of the alloy melt and reduced the occurrence of shrinkage porosity defects. When the optimal pressure was exceeded, the nucleation rate as well as the denseness of the alloy decreases. When the holding pressure was 0.035 MPa, the grain refining effect was the best and the microstructure was the most uniform. The yield strength, tensile strength, and elongation of the alloy reached the maximum values of 264.6 MPa, 290.8 MPa, and 7.7%, respectively. When the holding pressure was >0.035 MPa, the structure was not further refined; in contrast, the grains were larger, and the mechanical properties were inferior.