A Simulation and Fabrication Works on Optimization of High Pressure Aluminum Die Casting Part

From Hours to Production: How Simulation-Driven Design Eliminates HPDC Defects

This technical summary is based on the academic paper "A Simulation and Fabrication Works on Optimization of High Pressure Aluminum Die Casting Part" by S.Ö. ERTÜRK, L.C. KUMRUOĞLU, and A. ÖZEL, published in ACTA PHYSICA POLONICA A (2014). It has been analyzed and summarized for technical experts by CASTMAN.

Keywords

• Primary Keyword: High Pressure Die Casting Simulation
• Secondary Keywords: Die Casting Optimization, Mold Filling Analysis, Solidification Simulation, Air Entrapment, Aluminum Die Casting

Executive Summary

• The Challenge: Traditional trial-and-error High Pressure Die Casting (HPDC) die design is slow, costly, and often leads to critical defects like gas porosity and shrinkage from turbulent melt flow.
• The Method: The study utilized casting simulation software to systematically design and optimize the gating, ventilation, and overflow system for a complex aluminum part before any steel was cut.
• The Key Breakthrough: The simulation-driven design was so accurate that the physical mold required no revisions, and the resulting parts were free of critical defects, a finding confirmed by radiographic testing.
• The Bottom Line: Integrating High Pressure Die Casting Simulation into the initial design phase drastically cuts development time and ensures a "right-the-first-time" approach to mold manufacturing, eliminating costly rework.

The Challenge: Why This Research Matters for HPDC Professionals

In the competitive world of manufacturing, the goal is always to produce economical final products with minimal processing steps, a concept known as "net shape manufacturing." High-pressure die casting is a cornerstone of this approach, especially for aluminum and magnesium components in the automotive sector. However, the process is not without its challenges.

The high-velocity injection of liquid metal inherently promotes turbulent flow, which can trap the initial air within the mold. This leads to gas porosity, a harmful defect that compromises mechanical properties and pressure tightness. Traditionally, engineers have relied on experience and a costly trial-and-error method to place ventilation channels and overflows to combat this. This iterative process extends pre-production timelines and increases costs with each mold revision. This study was undertaken to demonstrate a more efficient, data-driven path to an optimized die design.

The Approach: Unpacking the Methodology

The research team adopted a simulation-first methodology to design the mold for an aluminum die-cast part. The process was systematic and data-driven:

1. Solidification & Parting Line Analysis: The process began by using simulation to analyze the part's solidification pattern, identifying the last regions to solidify (Fig. 1). This information, combined with CAD measurements of surface areas, was crucial for determining the optimal parting line to ensure the part could be easily ejected from the mold (Fig. 2).
2. Ingate Design & Flow Simulation: The researchers simulated various ingate designs, including a three-ingate model and a single emitter-type ingate. The simulations revealed that improper ingate design led to trapped air regions (Fig. 3). The single emitter-type ingate was chosen to avoid these defects and prevent "ingate blockage" caused by premature solidification in thin sections.
3. Process Parameter Calculation: Based on the part's mean thickness, an appropriate fill time was selected from an established data table (TABLE). Using the law of continuity (Q = V × A), the team calculated the required flow rate (4660 cm³/s) and designed the ingate dimensions to achieve a target melt velocity of 30 m/s.
4. Ventilation and Overflow Optimization: An initial filling simulation was run using a first-phase plunger speed of 0.5 m/s and a second-phase speed of 2.5 m/s. The results clearly identified potential air entrapment regions (Fig. 4). Based on this data, ventilation channels and overflows were strategically added to the die design.
5. Design Refinement: Further simulation of the revised design showed that while some issues were solved, colliding melt streams still occurred at the top of a core (Fig. 5a). To manage this turbulence, additional overflows were added to capture the problematic melt flow, leading to the final, optimized design (Fig. 5b).
6. Final Verification: A complete simulation, including the application of squeeze pressure during the intensification phase, was performed on the final mold design. This final check confirmed the design would produce a part free of shrinkage defects. The physical part was then cast and subjected to radiographic testing for real-world validation.

The Breakthrough: Key Findings & Data

[Based on the paper's Results section, present the 2-3 most significant findings with concrete data.]

Finding 1: Strategic Overflow Placement is Critical for Managing Turbulence and Air Entrapment

The initial simulations with a single ingate clearly showed where air would become trapped as the mold cavity filled (Figure 4b and 4c). After adding an initial set of three overflows, a new simulation revealed a secondary problem: colliding melt streams at the top of the core (Figure 5a). This turbulence could still lead to defects. Only after adding a final set of two more overflows (for a total of five) was the fill pattern optimized to direct this turbulent melt out of the part cavity and into an overflow pocket, as shown in the final design simulation (Figure 5b). This demonstrates that simulation is essential not just for placing vents, but for actively managing melt flow dynamics throughout the fill.

Finding 2: Simulation Accurately Predicts and Validates the Prevention of Shrinkage Defects

A crucial finding was the strong correlation between the simulation and physical testing. The final simulation, which included the effect of the high-pressure intensification phase (squeeze pressure), predicted a part free of shrinkage defects (Figure 6a). This prediction was directly confirmed by the radiographic inspection of the actual manufactured part. As shown in Figure 6b, the radiographic result revealed a sound casting with no visible internal shrinkage porosity, proving the accuracy of the simulation model and the success of the design. This one-to-one correlation validates the use of simulation as a reliable predictive tool, eliminating the need for physical trials to verify the effectiveness of the intensification phase.

Practical Implications for R&D and Operations

• For Process Engineers: This study suggests that adjusting the simulation to include the squeeze pressure of the intensification phase may contribute to accurately predicting and preventing shrinkage porosity, reducing scrap rates.
• For Quality Control Teams: The data in Figure 6 illustrates the direct effect of a simulation-optimized design on final part integrity, which could inform the use of simulation as a predictive tool to set quality inspection criteria before production begins.
• For Design Engineers: The findings indicate that the precise location and number of overflows (as seen in Figure 5) directly influence defect formation during mold filling, suggesting this is a valuable consideration for optimization in the early design phase.

Paper Details

A Simulation and Fabrication Works on Optimization of High Pressure Aluminum Die Casting Part

1. Overview:

• Title: A Simulation and Fabrication Works on Optimization of High Pressure Aluminum Die Casting Part
• Author: S.Ö. ERTÜRK, L.C. KUMRUOĞLU, AND A. ÖZEL
• Year of publication: 2014
• Journal/academic society of publication: ACTA PHYSICA POLONICA A
• Keywords: High Pressure Die Casting, Simulation, Optimization, Aluminum Alloys, Solidification, Mold Design

2. Abstract:

High-pressure die casting offers reduced costs due to its small tolerances and smooth surface finish. Casting parts produced are consumed by the automotive industry in millions. In this study, the use of computer aided engineering applications on design of high-pressure die-casting was studied. The influence of casting process steps in die design was studied and analyzed. The casting simulation software was used to improve design and solve problems. By using the simulation software in analyses of die design, the final design was reached in a few hours and thus the design process of pre-production was shortened and mold production was carried out with no revision on die material. Radiographic test was applied on the casting parts and the result shows good correlation between simulations of solidification result data. Also the results proved that the application of squeeze pressure in the intensification phase of high-pressure die casting process could be examined in the casting simulation.

3. Introduction:

The goal of any manufacturing industry is to minimize processing steps to produce a more economical final product, achieved by "net shape manufacturing". High-pressure die casting is a common process for near-net-shape components from aluminum and magnesium alloys, with high reproducibility of dimensions. The process involves injecting liquid metal at high velocities, which can promote turbulent flow and result in air entrapment, harming mechanical properties. To mitigate this, ventilation channels and overflows are used. The injection process has two phases: a slow shot and a fast shot. The complexity and speed of this process make computer simulation a necessary tool for controlling cavity fill and determining the correct location of vents and overflows.

4. Summary of the study:

Background of the research topic:

The study is set against the backdrop of industrial high-pressure die casting, a process critical to the automotive industry for producing large volumes of near-net-shape aluminum parts. The primary challenge is managing defects like gas porosity and shrinkage that arise from the high-speed injection process.

Status of previous research:

The paper notes that while theoretical and experimental studies on die design exist, they often rely on a trial-and-error method. The authors point out a gap in studies that present a step-by-step die design process using computer simulation to avoid these traditional pitfalls.

Purpose of the study:

The study aimed to demonstrate the use of computer-aided engineering (casting simulation software) to systematically design and optimize an HPDC die. The goals were to shorten the pre-production design process, solve common casting problems like air entrapment, and produce a defect-free part without costly physical revisions to the mold.

Core study:

The core of the study involved designing a die for an aluminum part by iteratively using simulation software. The researchers analyzed solidification, determined the parting line, optimized the ingate and runner system, calculated process parameters, and strategically placed overflows and vents. The final simulated design was then used to manufacture a physical mold and parts, which were then validated using radiographic testing to compare real-world results with simulation predictions.

5. Research Methodology

Research Design:

The research followed a simulation-led design and experimental validation methodology. The entire die design, from parting line to overflow placement, was developed and refined using casting simulation software.

Data Collection and Analysis Methods:

The primary method of data collection for validation was radiographic testing. A Baltospot GFD Industrial X-ray device was used to inspect the final cast parts according to EN 12681 and EN 444 standards. The results were then qualitatively compared with the solidification and shrinkage simulation results to check for correlation.

Research Topics and Scope:

The scope was focused on the design and optimization of a single high-pressure aluminum die-cast part. The research covered the influence of key die design elements (ingate, runners, overflows, vents) on mold filling dynamics, air entrapment, and final part soundness.

6. Key Results:

Key Results:

• The final die design was achieved in a few hours using simulation, significantly shortening the pre-production process.
• The mold was produced based on the simulation data and required no physical revisions.
• Radiographic examination of the produced parts showed no critical defects that would lead to rejection.
• A strong correlation was observed between the solidification simulation results and the radiographic test data.
• The study confirmed that simulation can effectively model the influence of squeeze pressure from the intensification phase on preventing shrinkage defects.

Figure Name List:

• Fig. 1. Solidification steps of casting part.
• Fig. 2. (a) Mold parting line, (b) draft analyses of casting part.
• Fig. 3. (a) Mold filling of model with three ingate, (b) mold filling of model with single and thin ingate.
• Fig. 4. (a) The solid model of casting part with emitter type ingate, (b) possible air entrapments in part, (c) possible air entrapments from section.
• Fig. 5. (a) Mold filling with three overflows attached model, (b) mold filling of part with five overflows.
• Fig. 6. (a) The shrinkage view from simulation result, (b) the radiographic result of casting part.

7. Conclusion:

One of the main goals of casting simulation is to avoid defects such as turbulence and air entrapments. The other is to prevent economic and time losses from traditional trial-and-error methods. In this study, the final design was reached in a few hours using computer simulation. This shortened the pre-production design process and allowed for mold production with no revision. Radiographic examination of the parts showed no defects, proving the accuracy of the design and production parameters. The overlap of radiographic results with solidification simulation showed that computer simulation, including the effect of solidification compression force, is a successful indicator of casting success.

8. References:

• [1] A. Jalili Nikroo, M. Akhlaghi, M. Ahmadi Najafabadi, Int. J. Adv. Manuf. Technol. 41, 31 (2009).
• [2] J. Campbell, Mater. Des. 21, 373 (2000).
• [3] P.K.D.V. Yarlagadda, E. Cheng Wei Chiang, J. Mater. Proc. Technol. 89-90, 583 (1999).
• [4] X. Dai, X. Yang, J. Campbell, J. Wood, Mater. Sci. Eng. A 354, 315 (2003).
• [5] X.P. Niu, B.H. Hu, I. Piwill, H. Li, J. Mater. Proc. Technol. 105, 119 (2000).
• [6] B.H. Hu, K.K. Tong, X.P. Niu, I. Pinwill, J. Mater. Proc. Technol. 105, 128 (2000).
• [7] F. Shehata, M. Abd-Elhamid, Mater. Des. 24, 577 (2003).
• [8] W.S. Zhang, S.M. Xiong, B.C. Liu, J. Mater. Proc. Technol. 63, 707 (1997).

Expert Q&A: Your Top Questions Answered

Q1: Why was a single emitter-type ingate chosen over the three-ingate design shown in Figure 3a?

A1: The simulation of the three-ingate design revealed that this configuration created trapped air regions where ventilation was not possible. As seen in Figure 3a, the converging flow fronts would trap air within the part. The single emitter-type ingate was selected to create a more progressive filling pattern that pushed air ahead of the melt front towards the overflows and vents, minimizing air entrapment.

Q2: The paper mentions an "ingate blockage" issue. How was this specifically addressed in the design?

A2: The paper notes that the shaft bearing region of the part was a thin section that would solidify early. Placing an ingate to feed through this area would risk the gate freezing off before the rest of the part was solid, a phenomenon known as ingate blockage. To prevent this, the ingate was positioned on an "appropriate two-piece flat surface," away from this thin section, ensuring the feeding path remained open during solidification.

Q3: How were the specific values for fill time and ingate velocity determined?

A3: The fill time was determined from the provided TABLE, which correlates part section thickness with recommended fill times. For this part's mean thickness, a time was selected. This fill time and the total volume of the part cavity were used to calculate the necessary flow rate (4660 cm³/s). Finally, the ingate's cross-sectional area was engineered to achieve the target ingate velocity of 30 m/s at that flow rate.

Q4: What was the specific purpose of adding the final two overflows to create the five-overflow design in Figure 5b?

A4: The simulation of the initial three-overflow design still showed colliding melt streams occurring at the top of the core (Figure 5a). This high-turbulence event could introduce defects. The final two overflows were added specifically to the top of the mold cavity to act as pockets that capture this turbulent, colliding melt, removing it from the final part and ensuring a sound casting.

Q5: The paper emphasizes the simulation of "squeeze pressure." Why is this significant for practical die casting?

A5: "Squeeze pressure" refers to the high pressure applied during the intensification phase at the end of the plunger stroke. This phase is critical for feeding the casting as it solidifies and shrinks, preventing shrinkage porosity. The significance is that the simulation software was able to model this final pressure application and accurately predict that it would eliminate shrinkage defects. This confirms that simulation can be used not just for mold filling but also for validating the effectiveness of the final, and most critical, stage of the HPDC process.

Conclusion: Paving the Way for Higher Quality and Productivity

This research provides clear, actionable evidence that the traditional, iterative approach to die casting design is obsolete. By front-loading the design process with High Pressure Die Casting Simulation, manufacturers can systematically identify and eliminate defects like air entrapment, turbulence, and shrinkage porosity before a single piece of tool steel is machined. The direct correlation between simulation and radiographic results proves that this method is not just theoretical but a reliable pathway to producing defect-free parts from the very first shot, drastically reducing development time and eliminating costly mold revisions.

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 Simulation and Fabrication Works on Optimization of High Pressure Aluminum Die Casting Part" by "S.Ö. ERTÜRK, L.C. KUMRUOĞLU, and A. ÖZEL".
• Source: https://doi.org/10.12693/APhysPolA.125.449

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