A Comparative Work on Die Casting and Squeeze Casting Techniques of A319 Cast Aluminium Alloy

Squeeze Casting vs. Die Casting: A Data-Driven Comparison for A319 Aluminum Alloy Components

This technical summary is based on the academic paper "A Comparative Work on Die Casting and Squeeze Casting Techniques of A319 Cast Aluminium Alloy" by M. Naveen Kumar, V. Mohanavel, C. Jayasekar, N. Dineshbabu and S. Udishkumar, published in the 11th International Conference on Science Engineering & Technology. It has been analyzed and summarized for technical experts by CASTMAN.

Keywords

• Primary Keyword: Squeeze Casting
• Secondary Keywords: Die Casting, A319 Aluminum Alloy, Mechanical Properties, Impact Strength, Hardness, Porosity Reduction

Executive Summary

• The Challenge: Conventional gravity die casting of A319 aluminum alloy can produce defects like porosity, which limits the mechanical performance required for demanding applications.
• The Method: The study directly compared the mechanical properties (hardness, impact strength) and microstructure of A319 alloy components produced by gravity die casting versus squeeze casting at pressures of 50, 75, and 100 MPa.
• The Key Breakthrough: Squeeze casting at 100 MPa significantly improved both impact strength (from 23 J to 31 J) and Brinell hardness (from 52 BHN to 69 BHN) compared to gravity die casting, while drastically reducing porosity.
• The Bottom Line: For high-performance A319 aluminum components, squeeze casting offers demonstrably superior mechanical properties and microstructural integrity over traditional gravity die casting.

The Challenge: Why This Research Matters for HPDC Professionals

In the automotive and aerospace industries, the demand for lightweight, high-strength components is relentless. While casting is one of the oldest and most effective methods for manufacturing metallic parts, conventional processes like gravity casting can introduce defects such as porosity and hot tears. These imperfections compromise the mechanical integrity of the final product, limiting its use in critical applications. This research was undertaken to explore a newer casting process—squeeze casting—as a method to eliminate these disadvantages and produce components with improved, reliable mechanical properties. The focus on A319 aluminum alloy is particularly relevant, given its widespread use in automotive components that are often subjected to impact loading.

The Approach: Unpacking the Methodology

The study conducted a direct comparison between two casting methods using A319 aluminum alloy.

• Materials & Equipment: The core material was A319 aluminum alloy, melted in a graphite crucible within a muffle furnace (1100°C). The die and punch were fabricated from H11 tool steel. The squeeze casting process utilized a 30-tonne hydraulic press.
• Process Parameters:
  • For both processes, the A319 alloy was superheated to 800°C, and the die was preheated to 350°C.
  • Gravity Die Casting: The molten metal was poured into the die and allowed to cool naturally.
  • Squeeze Casting: After pouring the molten metal into the die, a predetermined pressure was applied via a punch for 30 seconds during solidification. Three distinct pressure levels were tested: 50 MPa, 75 MPa, and 100 MPa.
• Evaluation: The resulting components were evaluated for two key mechanical properties:
  • Impact Strength: Tested according to ASTM E23 standard.
  • Hardness: Measured using a Brinell hardness tester with a 1000 kg load applied for 30 seconds.
  • Microstructure: Examined using optical microscopy to assess porosity and grain structure.

The Breakthrough: Key Findings & Data

The experimental results demonstrated a clear and consistent improvement in mechanical properties when using the squeeze casting technique, with performance scaling directly with the applied pressure.

Finding 1: Squeeze Casting Delivers Superior Impact Strength

The components produced via squeeze casting exhibited significantly higher impact strength compared to those from gravity die casting. The data shows a clear trend: as squeeze pressure increases, so does the material's ability to withstand impact.

• The gravity die-cast specimen had an impact strength of 23 J (Table 1).
• The squeeze-cast specimens showed progressively higher values: 25 J at 50 MPa, 27 J at 75 MPa, and 31 J at 100 MPa (Table 2). This represents a 35% improvement at the highest pressure.

Finding 2: Hardness and Microstructure are Significantly Enhanced by Pressure

A similar improvement was observed in the material's hardness. The application of pressure during solidification not only increased hardness but also refined the microstructure, leading to a more robust component.

• The gravity die-cast specimen registered a Brinell hardness number (BHN) of 52 (Table 3).
• The squeeze-cast specimens achieved higher hardness values: 57 BHN at 50 MPa, 62 BHN at 75 MPa, and 69 BHN at 100 MPa (Table 4).
• Optical micrographs (Figure 1) revealed that the gravity die-cast specimen contained some porosity. In contrast, the squeeze-cast specimens showed a minimal level of porosity and a fine-grained structure, with porosity levels decreasing as applied pressure increased.

Practical Implications for R&D and Operations

• For Process Engineers: This study suggests that adjusting the applied pressure during squeeze casting is a powerful tool for controlling final mechanical properties. Implementing pressures up to 100 MPa may contribute to producing A319 components with significantly reduced porosity and a fine-grained microstructure, leading to improved performance.
• For Quality Control Teams: The data in Table 2 and Table 4 of the paper illustrates the direct correlation between squeeze pressure and key mechanical properties like impact strength and hardness. This relationship could inform new, more stringent quality inspection criteria for high-performance components.
• For Design Engineers: The findings indicate that squeeze casting can produce near-net-shape, pore-free components with mechanical properties approaching those of a wrought product. This suggests that components designed for high-stress or fatigue-sensitive applications could be manufactured more reliably and with higher performance characteristics using this process.

Paper Details

A Comparative Work on Die Casting and Squeeze Casting Techniques of A319 Cast Aluminium Alloy

1. Overview:

• Title: A Comparative Work on Die Casting and Squeeze Casting Techniques of A319 Cast Aluminium Alloy
• Author: M. Naveen Kumar, V. Mohanavel, C. Jayasekar, N. Dineshbabu and S. Udishkumar
• Year of publication:
• Journal/academic society of publication: 11th International Conference on Science Engineering & Technology
• Keywords: Hardness, Temperature, Squeeze Casting; Die Casting; A319; Impact Strength.

2. Abstract:

In this article, a comparative work on mechanical properties of A319 alloy using gravity die casting and squeeze casting techniques was attempted. The components produced from both the processes were evaluated for hardness and impact strength. In this study the components obtained through die casting exhibited less mechanical properties. But, squeeze casting components exhibited improvement in mechanical properties when the squeeze pressure was increased form 50 MPa to 100 MPa. It was noticed that the mechanical properties of squeeze cast A319 alloy obtained at 100mpa was predominantly improved compared to gravity die casting and other two squeeze cast load conditions. Optical images reveals the minimal level of porosity when compared to the die cast specimen and also reveals the applied pressure increases gradually to the decrease porosity level. Thus squeeze casting has got the capability and potential to produce components with improved mechanical properties.

3. Introduction:

CASTING being the main driving force behind the production development in automotive industries. Now, newer casting processes are emerging to eliminate the disadvantages of conventional casting process. Casting processes are among the oldest methods for manufacturing metallic components. Through components made by Gravity casting exhibit uniformed good surface finish and good dimensional accuracy, but they possess some defects like porosity, hot tears etc., Squeeze casting also known as liquid-metal forging, is a process in which molten metal solidifies under pressure within closed die positioned between the plates of a hydraulic press. The applied pressure and the instant contact of the molten metal with the die surface produce a rapid heat transfer condition that yields a pore-free fine-grain casting with mechanical properties approaching those of a wrought product. The squeeze casting process can be easily automated to produce near-net to net shape high-quality components. Aluminum, magnesium, and copper alloy components are readily manufactured using this process. Improved mechanical properties are additional advantages of squeeze cast parts.

4. Summary of the study:

Background of the research topic:

Casting is a primary manufacturing process, especially in the automotive industry. However, conventional methods like gravity die casting suffer from defects such as porosity and hot tears. Newer processes are emerging to overcome these limitations. Squeeze casting, or liquid-metal forging, is one such process where molten metal solidifies under high pressure, yielding a pore-free, fine-grain product with superior mechanical properties.

Status of previous research:

The introduction cites several studies. Arami et al [1] explored micro porosity and fatigue resistance of A319 alloy. Cavaliere et al [2] noted the excellent mechanical properties from a fine, homogenous microstructure. Ghomashchi and Vikhrow [4] summarized the advantages of squeeze casting. Anand partheeban and Rajendran [5] studied the influence of squeeze pressure on mechanical properties, while Kim et al [7] reported that squeeze casting could improve mechanical properties by 15%-40% over gravity die casting.

Purpose of the study:

The study's purpose was to conduct a comparative analysis of the mechanical properties (specifically hardness and impact strength) of A319 aluminum alloy components produced using two different techniques: traditional gravity die casting and squeeze casting under varying pressures.

Core study:

The core of the study involved manufacturing A319 aluminum alloy samples using gravity die casting and squeeze casting at three different pressures (50 MPa, 75 MPa, and 100 MPa). These samples were then subjected to Brinell hardness tests, impact strength tests (ASTM E23), and microstructural examination to quantify the differences in their mechanical performance and internal structure.

5. Research Methodology

Research Design:

The research was designed as a comparative experiment. One group of samples was produced using a control method (gravity die casting), while three other groups were produced using the experimental method (squeeze casting) with a single varying parameter (applied pressure). The mechanical properties and microstructure of all groups were then measured and compared.

Data Collection and Analysis Methods:

• Data Collection: Hardness data was collected using a Brinell hardness tester, measuring the indentation diameter. Impact strength data was collected in Joules using an impact tester following ASTM E23 standards. Microstructural data was collected via optical micrographs.
• Analysis: The collected data was organized into tables to compare the values for hardness (BHN) and impact strength (J) across the different casting conditions. The optical images were qualitatively analyzed to compare porosity levels and grain structure.

Research Topics and Scope:

The research focused exclusively on A319 cast aluminum alloy. The scope was limited to comparing gravity die casting with squeeze casting at three specific pressure levels (50, 75, 100 MPa). The properties evaluated were hardness, impact strength, and microstructure.

6. Key Results:

Key Results:

• Squeeze casting produces components with higher impact strength and hardness compared to gravity die casting.
• Increasing the squeeze pressure from 50 MPa to 100 MPa results in a gradual and significant increase in both impact strength (from 25 J to 31 J) and Brinell hardness (from 57 BHN to 69 BHN).
• The squeeze cast component at 100 MPa showed a 35% improvement in impact strength and a 33% improvement in hardness compared to the gravity die cast component.
• Optical micrographs confirmed that squeeze casting leads to a minimal level of porosity and a fine-grained structure, with porosity decreasing as applied pressure increases.

Figure Name List:

• Figure. 1. Optical micrographs of the as cast samples (a) Die casting specimen, (b) Squeeze Casting at pressure of 50MPa, (c) Squeeze Casting at pressure of 75MPa, (d) Squeeze Casting at pressure of 100MPa

7. Conclusion:

In the present work, result concluded that the die cast and squeeze cast specimens ofA319 are prepared and tested in room atmospheric condition (30°C). Squeeze cast specimen has very few amount porosity, shrinkage, and voids compared to die cast samples. Impact strength of the squeeze cast products is detected to be very high compared to die cast specimens. Optical images reveals the minimal level of porosity when compared to the die cast specimen and also reveals the applied pressure increases gradually to the decrease porosity level. Microstructure of specimens reveals fine grain structure in the squeeze cast process. The applied pressure accelerated the cooling process and leads to nucleation in grain formation in many spots and finer grain structure is obtained fine grain structure will lead to improved hardness. The squeeze casting process of A319 brings enhanced mechanical properties when compared to the die casting process.

8. References:

• [1] Arami.H, Khalifehzadeh. R, Akbari. M, Khomamizadeh. F, 'Micro porosity control and thermal-fatigue resistance of A319 aluminum foundry alloy', Journal of Materials Science and Engineering, Vol. A 472, pp. 107-114.
• [2] Cavaliere P, Cerri E, Leo P. Effect of heat treatments on mechanical properties and damage evolution of thixoformed aluminium alloys. Mater Charact 2005;55:35-42.
• [3] Rincon E, Lopez. H.F, Cisneros. M.M, Mancha. H, Cisneros. M.A, 'Effect of temperature on the tensile properties of an as-cast aluminum alloy A319', Journal of Materials Science and Engineering, Vol. A 452-453, pp. 682-687.
• [4] Ghomashchi, M, R & Vikhrov, A 'Squeeze casting an overview', Journal of Materials Processing Technology, 2000 Vol.101, pp. 1-9.
• [5] Anand Partheeban C.M. and Rajendran M., 'Squeeze Casting-Influence of Squeeze pressures on Das and other related properties', Journal of Academia and Industrial Research (JAIR), Volume 2, Issue 1 June 2013
• [6] Aweda J.O., Adeyemi. M.B, 'Experimental determination of heat transfer coefficients during squeeze casting of Aluminium', Journal of Materials Processing Technology, Vol.209, pp. 1477-1483.
• [7] Kim E.S., Lee. K.H, Moon. Y.H, 'A feasibility study of the partial squeeze and vacuum die casting process', Journal of Materials Processing Technology, Vol. 105, pp. 42-48.
• [8] Vijian P., Arunachalam. V.P, 'Modeling and multi objective optimization of LM24 Aluminium alloy squeeze cast process parameters using genetic algorithm', Journal of Materials Processing Technology, Vol. 186, pp. 82-86.
• [9] Yang L.J., 'The Effect of solidification time in squeeze casting of Aluminium and Zinc alloys', Journal of Materials Processing Technology, Vol. 192-193, pp. 114-120.
• [10] Maleki.A, Shafyei. A, Niroumand. B 'Effects of squeeze casting parameters on the microstructure of LM13 alloy', Journal of Materials Processing Technology, Vol.209, pp. 3790-3797.

Expert Q&A: Your Top Questions Answered

Q1: Why was H11 tool steel chosen for the die and punch?

A1: The paper states, "Thus H11 tool steel is selected for both punch and Die." While the specific reasons for this choice are not detailed in the text, H11 is a common chromium hot-work tool steel known for its excellent toughness, resistance to thermal fatigue, and stability at high temperatures, making it a suitable material for casting dies that undergo repeated thermal cycling.

Q2: What is the mechanism by which squeeze pressure improves mechanical properties?

A2: According to the paper, the high level of applied pressure forces the molten metal into intimate contact with the die surface. This enhances the heat transfer rate, which in turn results in the formation of a fine-grained microstructure. The conclusion further explains that this accelerated cooling leads to nucleation in many spots, creating a finer grain structure that improves hardness. This pressure also minimizes the formation of shrinkage porosity, leading to a denser, more solid part with better impact strength.

Q3: What do the optical micrographs in Figure 1 reveal about the effect of pressure?

A3: Figure 1 provides a clear visual comparison. Figure 1(a), the gravity die-cast specimen, shows evidence of porosity. In contrast, Figures 1(b), (c), and (d)—representing squeeze casting at 50, 75, and 100 MPa, respectively—reveal a "minimal level of porosity." The images also show that as the applied pressure increases, the level of porosity gradually decreases, confirming the effectiveness of pressure in creating a more solid casting.

Q4: What were the specific process parameters for the squeeze casting tests?

A4: The study outlines several key parameters. The A319 aluminum alloy was superheated to a temperature of 800°C. The die was preheated to 350°C using a ceramic band heater. Once the molten metal was poured, a squeeze pressure of either 50, 75, or 100 MPa was applied to the melt for a duration of 30 seconds.

Q5: How does the "gravity die casting" in this study compare to High Pressure Die Casting (HPDC)?

A5: The paper describes its "die casting" process as pouring molten metal into a preheated die and allowing it to cool naturally. This is characteristic of gravity die casting, where gravity is the only force filling the mold. This differs fundamentally from squeeze casting, where a high static pressure is applied during solidification. It also differs from HPDC, which injects metal into the die at high velocity and pressure. The study focuses on the benefits of applying high static pressure during solidification (squeeze casting) versus a simple gravity-fed process.

Conclusion: Paving the Way for Higher Quality and Productivity

This research provides compelling evidence that for A319 aluminum alloy, the casting process has a profound impact on the final component's quality and performance. The core problem of porosity and suboptimal mechanical properties associated with gravity die casting can be effectively overcome by using Squeeze Casting. The study clearly demonstrates that by applying high pressure during solidification, it is possible to produce components with significantly lower porosity, a finer grain structure, and, consequently, superior hardness and impact strength. This data-driven insight is crucial for manufacturing high-integrity parts for the automotive and aerospace sectors.

"At CASTMAN, we are committed to applying the latest industry research to help our customers achieve higher productivity and quality. If the challenges discussed in this paper align with your operational goals, contact our engineering team to explore how these principles can be implemented in your components."

Copyright Information

• This content is a summary and analysis based on the paper "A Comparative Work on Die Casting and Squeeze Casting Techniques of A319 Cast Aluminium Alloy" by "M. Naveen Kumar, V. Mohanavel, C. Jayasekar, N. Dineshbabu and S. Udishkumar".
• Source: The paper was published as part of the 11th International Conference on Science Engineering & Technology proceedings. A direct URL or DOI was not provided in the source document.

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