Advanced Aluminum Die Casting Mold Solution for Automotive Transmission Housing
With the increasing demand for lightweight automotive components, aluminum high pressure die casting has become an important manufacturing technology for complex structural parts. However, developing a reliable die casting mold for large automotive components requires strong experience in mold design, molten metal flow control, thermal management, and defect prevention.
Transmission housings are critical components in automotive power systems. Due to their large size, complex geometry, thin-wall sections, and localized thick areas, they are highly challenging to manufacture. Common issues include incomplete filling, hot spots, shrinkage porosity, and sealing failures.
As an experienced aluminum high pressure die casting mold manufacturer, Raidy mold provides complete mold development solutions, including mold design, CAE simulation, gating optimization, cooling system design, and defect improvement.
In this project, Raidy developed a large transmission housing die casting mold and successfully improved critical shrinkage defects through optimized mold design and process control, achieving stable mass production.
Project Overview
The project was developed for an automotive transmission housing made from AlSi9Cu3(Fe) aluminum alloy.
Product specifications:
- Size: 560 mm × 440 mm × 400 mm
- Wall thickness: 3.5 mm
- Weight: 15.18 kg
- Annual production requirement: 50,000 pcs
The product required high internal quality and sealing performance:
- ASTM E505 internal quality standard;
- Sealing area porosity diameter below 0.4 mm;
- Porosity spacing above 8 mm;
- Less than 3 defects in inspection areas;
- Air leakage below 3 mL/min at 70 kPa.
Due to the complex structure and strict quality requirements, the main development challenges included:
- Long molten aluminum filling distance;
- Temperature loss during filling;
- Thick-wall hot spot areas;
- Internal shrinkage control.
High Pressure Die Casting Mold Design and Optimization
Machine Selection and Mold Structure Verification
For large aluminum die casting components, proper machine matching is essential to ensure mold stability.
Based on the product projection area and mold structure, the required locking force was calculated at approximately:
30,680 kN
Considering production requirements, Raidy selected an:
IDRA 37,000 kN high pressure die casting machine
for mold validation and mass production.
The shot sleeve filling ratio was also verified, with a calculated result of:
46.7%
which was within the recommended range for stable die casting operation.
Gating System Optimization
The gating system has a direct impact on molten aluminum flow, temperature distribution, and internal casting quality.
During mold development, Raidy optimized the gating design with the following objectives:
- Reduce molten metal flow distance;
- Maintain filling temperature;
- Improve filling balance;
- Enhance feeding capability in thick-wall areas.
Based on the product structure, a fan-shaped gating system was designed.
Main parameters:
- Gate thickness: 5 mm
- Gate location: Thick-wall area
- Gate installation: Slider-mounted structure
The optimized gating system improved filling stability and reduced risks such as cold shuts and incomplete filling.
CAE Simulation Before Mold Manufacturing
To reduce development risks, Raidy applied MAGMA simulation analysis before mold manufacturing.
The simulation evaluated:
- Filling behavior;
- Temperature distribution;
- Injection velocity;
- Solidification sequence;
- Shrinkage risk.
The analysis showed that after complete filling, the casting temperature remained between:
620°C–640°C
which was higher than the liquidus temperature of AlSi9Cu3(Fe):
578°C
The filling velocity at the gate area was approximately:
55 m/s
The simulation confirmed that the designed gating system provided stable filling performance.
However, the analysis also identified localized hot spots and potential shrinkage areas, which required further optimization.
Shrinkage Defect Improvement
Oil Return Hole Shrinkage Solution
During initial production trials, shrinkage defects were found in the oil return hole area.
Product features:
- Hole diameter: 14 mm
- Hole depth: 6 mm
The detected shrinkage size was:
2 mm × 1.5 mm × 2 mm
The defect rate reached approximately:
90%
The main reason was the local wall thickness reaching:
20 mm
This created a hot spot area where liquid feeding was insufficient during solidification.
To solve this issue, Raidy developed a local squeeze pin structure integrated into the mold slider.
Two squeeze solutions were evaluated:
- Surface squeeze;
- Hole squeeze.
Considering product structure and manufacturing cost, the hole squeeze solution was selected.
After further optimization of the squeeze pin sleeve design, the machining allowance was controlled to approximately 0.5 mm, significantly improving the feeding effect.
Final result:
The qualification rate reached 100%.
Bearing Hole Shrinkage Improvement
Another critical area was the small-end bearing hole.
Specifications:
- Diameter: 73 mm
- Depth: 30 mm
During trial production, shrinkage defects with a diameter of approximately:
3 mm
were found, with a defect rate of:
45%
The main cause was that the bearing hole was located at the final filling area, where lower mold temperature and insufficient feeding caused shrinkage.
To solve this issue, Raidy optimized the mold temperature control system.
The optimized parameters included:
- Mold temperature: 220 ± 10°C
- Return oil temperature: 170 ± 10°C
In addition, a high-pressure cooling control system was added to precisely manage cooling time.
After optimization:
- Mold thermal balance was improved;
- Shrinkage defects were effectively controlled;
- Defect rate was reduced to below 0.2%.
Project Results
Through Raidy mold engineering optimization, the project achieved:
| Item | Result |
|---|---|
| Oil return hole shrinkage | Eliminated, qualification rate reached 100% |
| Bearing hole shrinkage | Reduced from 45% to below 0.2% |
| Gating system | Improved filling stability |
| Cooling system | Improved mold temperature balance |
| Production | Stable mass production achieved |
Conclusion
Large aluminum high pressure die casting molds require comprehensive engineering capabilities to achieve reliable production.
Through CAE simulation, optimized gating design, squeeze pin technology, and advanced mold temperature control, Raidy mold successfully solved critical casting defects and improved product quality.
With experience in developing complex automotive aluminum die casting molds, Raidy provides customers with complete solutions from mold design and simulation analysis to defect improvement and production support.
Looking for a reliable aluminum high pressure die casting mold partner?
Contact Raidy mold for your next automotive die casting project.
