High Pressure Die Casting Research Articles

Influence of the casting processes and aging times on the microstructure and hardness of AlSi\(_{12}\)Cu cast alloys

The present study investigated the effects of the casting processes and aging times on the micro-structure and hardness of commercial AlSi12Cu alloys. The primary goal was to assess how various aging times affect the maximum hardness of the alloy and to evaluate the influence of cooling rates on hardness values obtained from sand casting (SC) and High-pressure die casting (HPDC). For both casting alloys, the solution heat treatment was performed at 540℃, followed by quenching. The alloys were then aged at 180℃ for various durations, ranging from 10 min to 50 h. The results reveal significant microstructural changes in the size and morphology of the eutectic silicon and intermetallic phases between the SC and HPDC. The α-Fe intermetallics predominantly exhibit a Chinese-script morphology in SC, whereas in HPDC, they are primarily present as polyhedral particles. The maximum hardness peak was observed at 8 h of aging in SC; in HPDC, it was achieved at only 4 h of aging. The results of the hardness and X-ray diffraction (XRD) analyses exhibit consistent trends, strong alignment, and good agreement with each other. The HPDC process, combined with heat treatment, significantly enhances the mechanical properties of cast aluminum alloys.

Tailoring 7075 alloys for semisolid state processing via in-situ formed TiAl 3

Traditional 7075 aluminum alloys are difficult to cast due to low viscosity and high shrinkage. This study addresses these challenges by forming TiAl 3 particles in situ, which enhance viscosity, reduce porosity, and prevent shrinkage cracks. The method involves adding a titanium master alloy to molten 7075 and using mechanical stirring to induce TiAl 3 formation. This improves processability, making the alloy suitable for high-pressure die casting (HPDC) in the aerospace and automotive industries. Microstructural analysis confirms that uniformly distributed TiAl 3 particles refine grains and enhance stability. The study employs microscopy, X-ray diffraction, thermodynamic simulations, and mechanical testing to validate structural properties, advancing 7075 alloy processing for large-scale applications in semisolid techniques.

Investigating effects of microstructural changes on microscopic strain field of high-pressure Die-Casting Al–Si alloys via RVE modeling

Heterogenous microstructures of High-Pressure Die-Casting (HPDC) Al–Si alloy lead to random strain concentrations during deformation. Different microstructural variations are considered, including Fe-rich phase and porosity, with focuses on different geometrical aspects. Representative Volume Element (RVE) models were established based on Electron Back Scatter Diffraction (EBSD) data using Finite Element Method (FEM). The effectiveness of the RVE models was verified by comparing predicted strain concentration locations with experimental results. The microstructural models were refined to explore effects of microstructural changes. The simulation results show that there is an interactive effect of porosity and Fe-rich phase on the microscopic strain field. When there is no porosity, the geometric properties of Fe-rich phase play an important role in changes of microscopic strain field. When average diameter of porosity is close to that of Fe-rich phase, position and shape of porosity dominate the microscopic strain field compared with that of Fe-rich phase.

Mechanisms of externally solidified crystal formation in aluminum high-pressure die casting

Aluminum high-pressure die castings (HPDC) are widely used in the automotive and other industries to achieve lightweight components with high productivity. However, the formation of externally solidified crystals (ESCs) during HPDC process can significantly reduce the mechanical performance, particularly the elongation and fatigue, of these cast parts. ESCs can be classified into two main types: Type I, consisting of large α-Al dendrites, and Type II, characterized by large crystals with fine dendrites that exhibit a clear boundary with the matrix. This study investigates the formation mechanisms of these two types of ESCs during the HPDC process. The effects of various process parameters on the formation and movement of ESCs were analyzed through high-pressure die casting trials, computer simulations, and water analog experiments. The investigation suggests that both types of ESCs start within the shot sleeve. Type I ESCs form and float within the melt, while Type II ESCs develop along the shot sleeve wall and plunger tip post-pouring. Increasing the melt temperature was found to reduce the formation of Type II ESCs. Both types of ESCs are carried into the die cavity during the filling process. Their distribution is closely related to the fast shot speed and the turbulence of the molten aluminum. Notably, a reduced fast shot speed was found to significantly decrease the number of ESCs transported into the die cavity, especially Type II ESCs. This reduction led to a considerable improvement in the mechanical performance of the cast components, particularly in terms of elongation. These findings on ESC formation as related to process parameters provide important guidance to achieve high-performance castings in industrial applications.

The effects of TiB2 on segregation bands, porosities and mechanical properties of hypoeutectic Al Si alloys by high pressure die-casting

The effects of TiB2 on segregation bands, porosities and mechanical properties of hypoeutectic Al Si alloys by high pressure die-casting

Automated optical system for quality inspection on reflective parts

The growing demand for high-quality components in various industries, particularly in the automotive sector, requires advanced and reliable inspection methods to maintain competitive standards and support innovation. Manual quality inspection tasks are often inefficient and prone to errors due to their repetitive nature and subjectivity, which can lead to attention lapses and operator fatigue. The inspection of reflective aluminum parts presents additional challenges, as uncontrolled reflections and glare can obscure defects and reduce the reliability of conventional vision-based methods. Addressing these challenges requires optimized illumination strategies and robust image processing techniques to enhance defect visibility. This work presents the development of an automated optical inspection system for reflective parts, focusing on components made of high-pressure diecast aluminum used in the automotive industry. The reflective nature of these parts introduces challenges for defect detection, requiring optimized illumination and imaging methods. The system applies deep learning algorithms and uses dome light to achieve uniform illumination, enabling the detection of small defects on reflective surfaces. A collaborative robotic manipulator equipped with a gripper handles the parts during inspection, ensuring precise positioning and repeatability, which improves both the efficiency and effectiveness of the inspection process. A flow execution-based software platform integrates all system components, enabling seamless operation. The system was evaluated with Schmidt Light Metal Group using three custom datasets to detect surface porosities and inner wall defects post-machining. For surface porosity detection, YOLOv8-Mosaic, trained with cropped images to reduce background noise, achieved a recall value of 84.71% and was selected for implementation. Additionally, an endoscopic camera was used in a preliminary study to detect defects within the inner walls of holes. The industrial trials produced promising results, demonstrating the feasibility of implementing a vision-based automated inspection system in various industries. The system improves inspection accuracy and efficiency while reducing material waste and operator fatigue.

The Effect of Sr, Ti, and B on the Crystallization Process and Mechanical Properties of the AlSi9Cu3(Fe) Alloy.

This article presents studies on the effect of Sr and TiB on the crystallization process, mechanical properties, hardness, and density index of the Al-Si alloy from the EN AC-46000 group, with a narrowed chemical composition, produced by die-casting and HPDC (high-pressure die casting) technology. The research used the Box-Wilson method to design the experiment and stepwise multiple regression. To identify the optimal amount of Sr and Ti in the analyzed alloy that would simultaneously guarantee the maximization of UTS, YS, Agt, and HBW and the minimization of the DI (density index), multi-criteria optimization was performed. The modifiers were added to the liquid alloy as AlSr10 and AlTi5B1 master alloys. It was found that for 0.02-0.04 wt.% Sr and 0.05-0.08 wt.% Ti in the die castings, the highest mechanical properties, such as UTS, YS, Agt, and HBW (treated as stimulants in the experiment), can be obtained simultaneously with the lowest alloy gasification identified by DI (treated as a destimulant in the experiment). It was also confirmed that the same amount of the above-mentioned elements in HPDC castings caused an increase in UTS by approx. 14%, YS by approx. 6%, A by approx. 47%, and HBW by approx. 13%, with a relatively small increase in DI by approx. 5% compared to the unmodified alloy.

A Novel Aluminium Alloys Design Strategy for Low Usage of Critical Raw Materials and High Casting Processibility for Automotive Applications

Abstract The fifth critical raw materials (CRMs) list published by the European Commission (EC) in 2023 poses new restrictions to the usage of lightweight materials in the transportation industry. As per the publication, aluminium (one of the most widely used lightweight metals in the aerospace and automotive industry) has been declared as CRM and an increased criticality trend in its major alloying elements e.g. silicon and magnesium has been observed. Therefore, a novel approach is required to implement the criticality concept in developing new aluminium alloys and their processing for different components in the automotive industry. The present study aims to describe the strategy required to reduce the usage of CRMs in aluminium alloys along with enhanced high-pressure die casting (HPDC) processibility. By integrating criticality and castability assessment, a contribution to the development of sustainable and high-strength aluminium alloys to meet the demands of modern manufacturing while addressing the global resource challenges is presented. This study will also support the implementation of the CRMs concept in materials research and development.

Quality Analysis of Mould Insert Produced by Additive Technology

The paper deals with monitoring the quality of a shaped part of a mould made from H13 tool steel using additive manufacturing. The shaped part of the mould is a key element in the casting of aluminium alloys by high pressure die casting (HPDC) technology and has a major influence on achieving the desired quality of the casting. This paper presents an evaluation methodology which includes the results of surface quality analysis and dimensional accuracy and stability of additively manufactured parts. These analyses were carried out from the production of the mould part to its application in the foundry operating conditions. The comprehensive analyses offer an overall view of the changes caused by individual technological operations. These operations are additive manufacturing, heat treatment, machining, and final coating before implementation into the operating conditions of the foundry. The paper also describes monitoring the quality of the mould part in regular cycles during the production of aluminium castings. This methodology and the results provide new insights in the field of engineering metallurgy.

Ester-Based Lubricant and Anti-Leidenfrost Additive Solutions on Aluminum High-Pressure Die-Casting Applications

The high-pressure die-casting process is growing since it is a cost-effective solution in the production of lightweight parts for a variety of industries. Nevertheless, the harsh working conditions of the die lead to premature failing and poor quality of the produced parts. Lubricants are applied to cooling the die surface and create a protective film to minimize die wear. However, the high temperature of the die during the casting production makes it difficult for the lubricant to reach the die surface due to the Leidenfrost effect. In this study, the effectiveness of newly developed ester-based lubricants designed to address Leidenfrost phenomenon in high-pressure die-casting is evaluated at laboratory and pilot plant scale. The new lubricants are based on the same ester solution; however, one of them includes a specially formulated anti-Leidenfrost additive to optimize performance at the temperature ranges typically encountered in industrial aluminum high-pressure die-casting processes. The results show a correlation between lubricant heat-transfer capability and aluminum adhesion. Additionally, a pilot plant methodology for testing newly formulated lubricants has been established while the experimental methodology developed for assessing heat-transfer capability is validated as a rapid and cost-effective approach for evaluating lubrication alternatives for high-pressure die-casting applications. Finally, the efficiency of environmentally friendly ester-based lubricants for high-temperature applications has been demonstrated.

Microstructure and Mechanical Properties of High-Pressure Die-Casting Mg-Al-RE Alloys with Minor Ca Addition.

With the increasing demand for magnesium (Mg) alloys with high strength and good ductility, this study explores high-pressure die-cast (HPDC) Mg-6Al-2RE (AE62), Mg-8Al-2RE (AE82) and Mg-8Al-2RE-0.2Ca (AEX820) alloys (wt. %). Their microstructures and mechanical properties are investigated under both as-cast and T5-aged (direct artificial aging after casting) conditions. HPDC alloys consist of outer fine-grain regions and inner coarse α-Mg grains with abundant eutectic phases. The increasing addition of Al has an insignificant effect on the refinement of the grain size of α-Mg, but it significantly influences the morphology and area fraction of the second phases. The average grain sizes of α-Mg in HPDC AE62, AE82 and AEX820 alloys are approximately 4.0 μm, 3.9 μm and 3.7 μm in the edge regions and about 13.9 μm, 12.8 μm and 12.1 μm in the core regions, respectively. When aged at 200 °C, β-Mg17Al12 precipitates are predominantly formed in the studied alloys. Increasing the Al and Ca concentrations effectively refines the microstructures and enhances the aging hardening response and the strength, albeit at the expense of considerably reduced ductility. The peak-aged AE62 alloys demonstrate balanced tensile properties, with ultimate tensile strength (UTS), yield strength (YS), and elongation at fracture (Ef) at room temperature of ~241 MPa, ~141 MPa and ~7.1%, respectively, and values of ~129 MPa, ~96 MPa and ~19.8%, respectively, at 175 °C. Compared to peak-aged AE62 alloy, the UTS and YS of peak-aged AEX820 alloys are improved by ~6.7% and ~14.2%, respectively, at RT and ~8.5% and ~12.5% at 175 °C, while Ef is decreased by 35.2% at RT and 33.3% at 175 °C, primarily due to the high area fraction of secondary phases.

Effects of Porosity on Mechanical Properties of Castings in High-Pressure Die-Casting Process

Effects of Porosity on Mechanical Properties of Castings in High-Pressure Die-Casting Process

Lattice Structure for Improving Cooling Uniformity in HPDC Mould Corners

Conformal cooling channels have demonstrated significant advantages for cast parts and 3D-printed moulds in the high-pressure die casting (HPDC) process. However, the complex geometry of moulds, characterised by small intrusions, sharp corners, and fins, often results in nonuniform cooling in certain regions, leading to overcooling or overheating. This study proposes integrating lattice structures within specific regions of 3D-printed moulds or inserts as an additional control parameter to enhance cooling uniformity by increasing thermal resistance in targeted areas. A validated three-dimensional Computational Fluid Dynamics (CFD) model was employed to incorporate three types of lattice structures, aiming to limit local heat flux in overcooled areas. The model specifically addresses the cooling of an aluminium alloy profile with 90-degree-angled corners, using H13 steel mould properties. The results indicate that implementing a lattice structure as a sleeve around the cooling pipe at the corner two sides improved temperature uniformity by over 42%. However, this increased thermal resistance also led to a 16 °C rise in corner temperature. These findings suggest that implementing lattice structures in the mould can improve cooling uniformity. However, they should be positioned away from the thickest regions of the mould to avoid increasing the modelling time.

Influence of Geometrical Design on Defect Formation of Commercial Al-Si-Cu-Mg Alloy Fabricated by High-Pressure Diecasting: Structural Observation and Simulation Validation

Near-net-shaped metal products manufactured by high-pressure diecasting (HPD) encountered more or less critical failure during operation, owing to the development of micro-defects and structural inhomogeneity attributed to the complexity of geometrical die design. Because the associated work primarily relies on technical experience, it is necessary to perform the structural analysis of the HPDed component in comparison with simulation-based findings that forecast flow behavior, hence reducing trial and error for optimization. This study validated the fluidity and solidification behaviors of a commercial-grade Al-Si-Cu-Mg alloy (ALDC12) that is widely used in electric vehicle housing parts using the ProCAST tool. Both experimental and simulation results exhibited that defects at the interface of a compact mold filling were barely detected. However, internal micro-pores were seen in the bolt region, resulting in a 17.27% drop in micro-hardness compared to other parts, for which the average values from distinguished observation areas were 111.24 HV, 92.03 HV, and 103.87 HV. The simulation aligns with structural observations on defect formation due to insufficient fluidity in local geometry. However, it may underestimate the cooling rate under isothermal conditions. Thus, the simulation used in this work provides reliable predictions for optimizing HPD processing of the present alloy.

Optimisation of Hot-Chamber Die-Casting Process of AM60 Alloy Using Taguchi Method.

This paper presents the effect of hot-chamber HPDC (high-pressure die casting) process parameters on the porosity, mechanical properties, and microstructure of AM60 magnesium alloy. To reduce costs, a Taguchi design of the experimental method was used to optimise the HPDC process. Six parameters set at two levels were selected for optimisation, i.e., piston speed in the first phase, piston speed in the second phase, molten metal temperature, piston travel, mould temperature, and die-casting pressure (the pressure under the piston). Signal-to-noise (S/N) ratios were used to quantify the present variations. The significance of the influence of the HPDC parameters was assessed using statistical analysis of variance (ANOVA). The results showed that the die-casting pressure had the most significant influence on the porosity of the AM60 alloy. Moreover, piston speed in the first phase, second phase, and die-casting pressure had the most important effects on tensile strength. It is well known that porosity determines the mechanical properties of die castings; however, in AM60 alloy, changes in the HPDC parameters also contribute to microstructural changes, mainly through the formation of Externally Solidified Crystals.

Influence of High-Speed Ram Transition Position on Porosity and Mechanical Properties of Large One-Piece Die-Casting Al-Si-Mn-Mg Aluminium Alloy.

The high-pressure die-casting process can effectively manufacture aluminium alloy castings with complex shapes and thin wall thicknesses. However, due to the complex flow characteristics of the liquid metal during the mould-filling process, there are significant differences in the mechanical properties of different parts of the casting. This paper analyses the effect of the high-speed ram transition position on porosity and mechanical properties of Al-Si-Mn-Mg aluminium alloys in the high-pressure die-casting (HPDC) process, comparing the 1160 mm and 1200 mm positions. Using a comprehensive methodology that combines CT, tensile tests, and SEM, the research demonstrates that the 1160 mm position improves mechanical properties and reduces porosity, with a larger gap at the near-end of the casting, where the yield limit and elongation of the casting increased by 13% and 25% at 1160 mm compared to 1200 mm, respectively. This result shows that appropriate adjustment of the high-speed ram transition position can effectively optimise the organisational structure of thin-walled castings, and then improve their mechanical properties.

Innovative cooling solutions of HPDC technology

In High Pressure Die Casting (HPDC), the so-called sliders are moving components of the mould, that can form cavities, holes, and undercuts. Sliders differ greatly from fixed- and moving mould halves regarding cooling and thermal balance. Typically, mould halves can range from a few hundred kilograms to several tonnes in size, whereas sliders have a significantly lower mass, and therefore their thermal balance changes much more drastically during casting cycles. Sliders can also be used to improve local heat dissipation in different areas. They are equipped with cooling holes through which the hole-forming cores, which penetrate deep into the mould cavity, can be tempered so that a significant amount of heat can be removed from the solidifying metal during the mould-filling process. As the industry produces increasingly complex castings, the cooling systems for the various moulds, inserts and cavities have evolved accordingly as the complexity of the castings has increased. This has resulted in innovative solutions and developments in the cooling of moulds and mould inserts, such as the use of 3D-printed metal inserts with improved heat dissipation. This article compares the cooling differences between traditionally cooled and 3D-printed sliders. We investigate cooling efficiency and tool temperatures at different cooling intensities through simulation experiments. Furthermore, at the end of the solidification phase, we examine the mold temperatures and the heat extracted for different molds and cooling intensities.

Prediction of the Stability of the Casting Process by the HPDC Method on the Basis of Knowledge Obtained by Data Mining Techniques.

High-pressure die casting (HPDC) of aluminum alloys is one of the most efficient manufacturing methods, offering high repeatability and the ability to produce highly complex castings. The cast parts are characterized by good surface quality, high dimensional accuracy, and high tensile strength. Continuous technological advancements are driving the increase in part complexity and quality requirements. Numerous parameters impact the quality of a casting in the HPDC process. The most commonly controlled parameters include plunger velocity in the first and second phases, switching point, and intensification pressure. However, a key question arises: is there a parameter that can predict casting quality? This article presents an exploratory analysis of data recorded in a modern HPDC casting machine, focusing on the thickness of the biscuit. The biscuit is the first component of the casting runner system, with a diameter equivalent to that of the injection chamber and a height linked to various processes and mold characteristics. While its diameter is fixed, the thickness varies. The nominal thickness value and tolerances are defined by the process designer based on calculations. Although the thickness of the biscuit does not affect the casting geometry, it influences porosity and cold-shot formation. This study aimed to determine the relationship between biscuit thickness and casting quality parameters, such as porosity. For this purpose, a series of injections was produced using automated gating, and biscuit thicknesses were examined. This article presents quality assessment tools and statistical analyses demonstrating a strong correlation between biscuit thickness and casting quality. The knowledge gained from the methodology and analyses developed in this study can be applied in support systems for the quality diagnostics of HPDC castings.

Corrosion Behavior of High Pressure Die Cast Al Alloys in Neutral and Acidic 3.5 Wt.% NaCl Solutions

High Pressure Die Cast (HPDC) Al alloys are of interest as automotive structural materials. Owing to the unique processing conditions, HPDC Al alloys may exhibit distinct microstructures compared to other cast automotive Al alloys. In this work, we are evaluating corrosion behavior of several HDPC Al alloys with varied chemical compositions in comparison with non-HPDC commercial Al cast alloy(s) using electrochemical impedance and polarization techniques, and long-term exposure sample characterization in typical 3.5 wt.% NaCl with and without HCl addition to lower pH. A lower pH NaCl solution is used to increase the frequency of corrosion attack growth for collection of statistical corrosion depth data. The key results will be discussed to allow semi-quantitative comparison of HPDC Al alloy resistance against corrosion initiation and growth.

The Effect of Hidden Damage on Local Process Variability in Al-10 Pct Si Alloy High-Pressure Die Castings

An approach to evaluate and quantify process variability in the mechanical performance of castings is explored. The process variability describes the effect of hidden damage given to the metal before solidification on the material performance measured by elongation to failure. The approach is demonstrated on a casting produced by high-pressure die casting (HPDC) with different filling conditions in serial production. Statistical analyses have been conducted on data obtained from several positions throughout the casting to determine whether a position is performing differently from other positions. The results show that elongation in most positions follows the same Weibull distribution. However, the local evaluation shows that one position stands out and follows a separate distribution. Casting simulations, Digital Image Correlation (DIC), and Scanning Electron Microscopy (SEM) reveal that this position displays an increased amount of hidden damage that causes the local reduction in elongation. The investigated changes in prefill amount do not significantly affect the material quality, which is more controlled by the quality of the melt and the nature of mold filling.