With the increasing demand for lightweight automotive components, new energy structural parts, and high-performance aluminum die castings, traditional high-pressure die casting processes are gradually revealing limitations in terms of density, porosity control, and post-processing adaptability. High-vacuum die casting technology has emerged in this context, significantly improving the internal quality and overall performance of castings by effectively removing gas from the mold cavity during the filling process. This article from Raidy Mold Manufacturer will systematically analyze the technical advantages and engineering implementation methods of high-vacuum die casting molds, focusing on their design principles, structural key points, and practical application examples.
What is Vacuum Die Casting?
• Vacuum die casting refers to the process of rapidly removing air and gases from the die casting mold cavity and gating system using a vacuum system before or during the filling of molten metal. This effectively eliminates or significantly reduces porosity, shrinkage, and dissolved gases inside the die casting, improving the density, mechanical properties, airtightness, and surface quality of the casting. It is a high-end, advanced high-pressure die casting forming process.
• Achieving vacuum die casting requires both a vacuum die casting mold and a vacuum equipment system (vacuum machine, piping, control system, etc.). This is the primary condition for realizing this process. If only a vacuum mold is available without a vacuum machine and corresponding control system, the process effect is essentially the same as ordinary high-pressure die casting, failing to achieve true vacuum forming and the goals of reducing porosity and improving casting performance.
Compared to ordinary high-pressure die casting, vacuum die casting establishes a stable negative pressure environment before or during mold filling, effectively reducing air entrapment within the mold cavity and fundamentally improving the internal porosity problem of castings. Ordinary die castings often exhibit unevenly distributed porosity, shrinkage porosity, and internal air inclusions, while vacuum die castings exhibit higher density, more stable mechanical properties, and superior airtightness and weldability, making them particularly suitable for high-end structural and functional parts with high requirements for internal quality and post-processing.
Advantages of High-Vacuum Mold Die Casting:
1. Increased internal density of castings after vacuum die casting.
2. Increased yield for castings requiring surface treatment. Surface treatments including powder coating, Teflon coating, electrophoresis, painting, electroplating, and oxidation show significant effects.
3. For die casting, lower pressure than with ordinary molds is sufficient to produce high-quality products. This means products from high-pressure die casting molds are cleaner, with fewer burrs compared to ordinary molds, thus reducing the failure rate of high-pressure die casting molds (such as collapse and dents).
4. For die castings with pressure-bearing components (requiring airtightness), vacuum die casting improves porosity by 10-20%.
5. Significant improvement is seen in die castings with a machining depth of 4-5mm.
In addition to improving casting density and molding stability, vacuum die casting significantly improves the overall performance of castings in post-processing steps. Die castings using vacuum processes are more stable in processes such as spraying, electroplating, anodizing, electrophoresis, welding, and heat treatment, and are less prone to quality problems such as blistering, bursting, bulging, and delamination, significantly improving finished product yield and consistency. Meanwhile, its superior airtightness and pressure-bearing capacity enable it to meet higher levels of sealing and safety performance requirements.
High Vacuum Die Casting Applicable Products and Industries
High vacuum die casting is widely used in the field of aluminum alloy die castings where high density, airtightness, structural strength, and post-processing performance are required. Typical applications include: battery trays for new energy vehicles, motor housings, electronic control housings, automotive subframe structural components, braking system components, communication equipment housings (such as 5G chassis and filter housings), electronic equipment heat dissipation housings, and various pressure-bearing and sealing housings.
These products typically have characteristics such as large variations in wall thickness, complex structures, and high load-bearing or sealing requirements. Traditional die casting struggles to consistently meet quality standards, while high vacuum die casting effectively improves their internal quality and overall reliability.
High Vacuum Die Casting Mold Design and Development Process
The development of high vacuum die casting molds must follow a systematic and engineering-oriented design process. First, a product structure and process manufacturability analysis (DFM) is conducted to assess part wall thickness, ribs, intersection areas, and potential porosity risk areas. Then, mold flow simulation software (such as MAGMA) is used to verify and optimize the filling path, vacuum evacuation channel, and solidification behavior. Based on this, the overall design of the sealing structure, venting system, slider structure, and cooling system is completed. After the high-pressure die-casting mold is manufactured, multiple rounds of mold trials and parameter optimization are conducted to verify the internal quality, dimensional stability, and production cycle time of the casting, ultimately achieving stable mass production and delivery.
Die-casting Mold Case Design Explanation
Product Information:
1. Dimensions: 290X180X223
2. Weight: 1.36Kg
3. Casting Pressure Capacity: 6Kg
Mold Structure Analysis:
1. Uses two large sliders on the left and right sides;
2. Feeding method: Feeding from both sides;
3. Vacuum mold design is adopted;
4. ￠90 injection diameter is used.
Rendering after mold parting
High-pressure die-casting mold parting requires consideration of material splatter to prevent it from burning the sealing strip.
Key Locations Explained
In the left image, a sealing groove is created at the location circled in red within the mold frame. A sealing ring is placed on the mold. (The sealing ring must be heat-resistant.)
Generally, a 380℃ sealing strip is used
This uses a venting block type vacuum system. The venting block also needs to be sealed. Venting block design considerations: Gas must be vented, but aluminum must not escape, otherwise it will clog the pipes.
Vacuum Mold Design Summary
• 1. Sealing Locations Must Be Set in the Mold Frame
The mold frame is the foundation of the entire mold vacuum system. Continuous sealing grooves should be created at the parting surface and key connection points, and high-temperature resistant sealing rings should be installed to ensure that the mold cavity does not leak during vacuuming, providing the prerequisite for forming a stable negative pressure environment.
• 2. Seals should be installed at the ejector pin location. The ejection system is a common source of air leakage. A sealing structure (such as a sealing ring or labyrinth seal) needs to be designed between the ejector pin and the guide hole to prevent air from entering the mold cavity through the ejector pin gaps, ensuring vacuum efficiency and stability.
• 3. Seals should be installed on the venting block. The venting block is both a vacuum channel and a key component for intercepting molten aluminum. Its structure must have the dual function of “air expulsion and aluminum prevention,” and a reliable seal should be installed at its installation location to prevent molten aluminum from entering the vacuum pipeline and causing blockage or system failure.
• 4. Seals should also be installed on the slider. Since the slider has movement clearance, it is a potential source of air leakage. Sealing grooves or sealing strips should be installed on the contact surface between the slider and the mold frame to reduce vacuum leakage and improve molding stability and casting consistency.
• 5. If conditions permit, it is best to install a sealing ring on the barrel. If a sealing structure can be installed at the end of the injection system barrel, it can further reduce air entrapment during the injection process, improve the purity of molten aluminum filling, which is especially important for high-density, heat-treatable castings.
• 6. For high-pressure die casting mold design, it is best to use an integral material cylinder injection mold.
Using an integral material cylinder structure reduces connection surfaces and assembly gaps, which is beneficial for achieving higher sealing performance and structural rigidity, while also improving filling stability and system reliability.
In summary, the core of high-vacuum die casting molds lies in the systematic and comprehensive sealing design and the synergistic application of a stable and reliable vacuum system. By rationally arranging the sealing of key locations such as the mold frame, slider, ejector pin, venting block, and material cylinder, not only can the density and surface quality of the casting be significantly improved, but the mold failure rate and production costs can also be effectively reduced. High-vacuum die casting technology has become a key manufacturing method for high-end structural components, pressure-bearing components, and products with stringent post-processing requirements, and its application value and promotion prospects will continue to expand.
Chooses Raidymold, Starting a High-Vacuum Die Casting Collaboration
If you are looking for a partner with genuine high-vacuum die casting mold design and manufacturing capabilities, Raidy Molds is a trustworthy choice. We possess mature experience in vacuum die casting mold development, along with advanced mold flow analysis technology and a comprehensive engineering support team. We can provide integrated solutions for your products, from design optimization to stable mass production. Feel free to submit your drawings or samples to us at any time. Raidy Molds will provide you with professional DFM evaluation and vacuum die casting technical solutions to help your products achieve higher quality, lower costs, and faster delivery.
