In the production of aerospace casting parts, we often encounter complex geometries that pose significant challenges in achieving high-quality outcomes. One such component is the gear pump shell used in aviation fuel systems, which requires precise manufacturing to meet stringent performance standards. These castings aerospace applications demand exceptional integrity due to their role in handling high-pressure fluids. In our study, we focused on optimizing the casting process for an aluminum alloy gear pump shell, which exhibited a high rate of defects, particularly underfilling in thin-walled sections. The use of advanced simulation tools like AnyCasting allowed us to analyze and refine the process, leading to substantial improvements in quality and yield for these critical aerospace casting parts.
The gear pump shell is a典型 example of complex castings aerospace components, featuring intricate internal passages and varying wall thicknesses. For instance, the oil filter tank area has a thin wall of 4.5 mm, while other sections like the “8-shaped cavity” can be as thick as 40 mm. This disparity in geometry often leads to thermal imbalances during casting, resulting in defects. In our initial production, the qualification rate was only 22.2%, with underfilling defects accounting for 45.3% of rejections. Such issues not only increase costs but also pose risks to the reliability of aerospace systems. Therefore, we embarked on a comprehensive study to address these challenges through process optimization, leveraging simulation to guide our improvements for aerospace casting parts.
To understand the casting process, we first examined the工艺特点 of the metal mold tilt casting method employed for these aerospace casting parts. This technique involves gradually tilting the mold to fill the cavity with molten aluminum, minimizing turbulence and gas entrapment. The shell requires multiple sand cores to form its complex internal structures—seven cores in total, with four combined into a set and three installed individually. This setup, while necessary, adds to the process complexity and increases the likelihood of defects in critical areas like the oil filter tank. The mold materials, primarily H13 tool steel, have high thermal conductivity, which accelerates heat loss in thin sections, exacerbating issues in castings aerospace applications. We summarized the key parameters in Table 1 to provide a clear overview of the initial process conditions.
| Parameter | Value | Description |
|---|---|---|
| Alloy Material | ZL101A | Aluminum alloy used for castings aerospace |
| Mold Material | H13 Tool Steel | High thermal conductivity material |
| Pouring Temperature | 720°C | Initial setting for aerospace casting parts |
| Mold Preheating Temperature | 280°C | Uniform preheating in initial process |
| Coating Thickness | 200 μm | ZnO-based coating for mold surface |
In our工艺性分析, we conducted a detailed structural and simulation-based assessment of the aerospace casting parts. The铸件结构分析 revealed that the oil filter tank, a large thin-walled section (Φ120 mm × 145 mm with 4 mm thickness), is isolated from the main body and lacks thermal support from risers. This design leads to rapid heat dissipation, making it prone to underfilling. Using AnyCasting software, we simulated the filling and solidification processes to identify the root causes. The governing equations for fluid flow and heat transfer in casting simulations include the continuity equation, momentum equation, and energy equation. For instance, the heat conduction can be described by Fourier’s law: $$ q = -k \nabla T $$ where \( q \) is the heat flux, \( k \) is the thermal conductivity, and \( \nabla T \) is the temperature gradient. In the context of castings aerospace, these principles help predict defect formation.
Our铸造仿真分析 involved setting up a numerical model with approximately 9 million uniform grids. We input material properties, such as the thermal conductivity of ZL101A aluminum alloy and H13 steel, and defined the tilt casting parameters across seven stages, as shown in Table 2. The simulation results indicated that during filling, the aluminum velocity remained below 50 cm/s, avoiding excessive turbulence. However, the temperature field showed that the oil filter tank area cooled rapidly, with temperatures dropping to around 590°C upon completion of filling—close to the solidification range of ZL101A (555°C to 615°C). This early solidification hindered proper filling, leading to defects. The solidification simulation further confirmed that this area solidified first, within 42.5 seconds for 5% solidification, due to the high cooling rate. We expressed the solidification time using Chvorinov’s rule: $$ t = B \left( \frac{V}{A} \right)^2 $$ where \( t \) is solidification time, \( B \) is a constant, \( V \) is volume, and \( A \) is surface area. For thin-walled sections in aerospace casting parts, the high \( A/V \) ratio results in shorter solidification times, increasing defect risks.
| Tilt Stage | Angle (°) | Speed (1/400 L/min) |
|---|---|---|
| Stage 1 | 85 | 50 |
| Stage 2 | 65 | 65 |
| Stage 3 | 45 | 80 |
| Stage 4 | 30 | 90 |
| Stage 5 | 15 | 75 |
| Stage 6 | 1 | 45 |
| Stage 7 | -2 | 10 |
The模具结构分析 highlighted that the combination of thin walls, absence of risers, and high thermal conductivity of H13 steel (approximately 40 W/m·°C) contributed to the heat loss. The cooling rate in the oil filter tank area was measured at 30°C/min without insulation, which is critical for aerospace casting parts. To quantify this, we can use the heat transfer equation: $$ \frac{dT}{dt} = \frac{k A (T_m – T_0)}{\rho c V} $$ where \( \frac{dT}{dt} \) is the cooling rate, \( T_m \) is melt temperature, \( T_0 \) is mold temperature, \( \rho \) is density, and \( c \) is specific heat. This equation underscores the need for thermal management in castings aerospace to prevent defects.
Based on our analysis, we implemented several工艺改进措施 aimed at enhancing the thermal conditions during casting. First, we increased the pouring temperature from 720°C to 740°C, the upper limit of the process specification, to improve fluidity. Second, we modified the mold preheating: instead of uniform preheating at 300-350°C, we locally preheated the steel core and outer mold areas around the oil filter tank to 380-400°C. Third, we optimized the application of insulation coating—using a ZnO-based coating with a thickness of 0.2-0.3 mm—and ensured frequent reapplication, especially after every five castings, to maintain its effectiveness. The impact of these measures is summarized in Table 3, showing how they address the thermal challenges in aerospace casting parts.
| Improvement Measure | Previous Value | Optimized Value | Effect on Castings Aerospace |
|---|---|---|---|
| Pouring Temperature | 720°C | 740°C | Enhanced aluminum fluidity |
| Mold Preheating | 300-350°C (uniform) | 380-400°C (localized) | Reduced heat loss in thin sections |
| Coating Application | Infrequent | Frequent reapplication | Improved thermal insulation |
After implementing these changes, we observed significant improvements in the castings aerospace quality. The AnyCasting simulation for the optimized process showed that the oil filter tank area reached temperatures around 700°C upon filling completion, compared to 590°C previously. The solidification time for 5% solidification increased to 46.6 seconds, indicating better heat retention. This translated to a reduction in underfilling defects from 45.3% to 8.4%, and the overall qualification rate for aerospace casting parts rose from 22.2% to 68.7%. The success of these optimizations underscores the importance of simulation-driven approaches in enhancing the reliability of castings aerospace.
In conclusion, our study demonstrates the effectiveness of using AnyCasting simulation to optimize the casting process for complex aerospace casting parts. By analyzing temperature fields, flow patterns, and solidification behavior, we identified key factors contributing to defects and implemented targeted improvements. The integration of higher pouring temperatures, localized preheating, and consistent insulation coating application significantly reduced underfilling issues in the gear pump shell. This approach not only improves the quality of individual components but also provides a framework for optimizing other castings aerospace, ensuring higher yields and better performance in critical aviation applications. Future work could explore additional parameters, such as alternative alloy compositions or advanced coating materials, to further enhance the process for aerospace casting parts.