5 Tips for Working With Aluminium High Pressure Die Casting

5 Tips for Working With Aluminium High Pressure Die Casting

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High Pressure Die Casting (HPDC) is a powerful manufacturing process used to create high volumes of components from materials like aluminium, zinc, and magnesium. However, the process is far more complex and precise than simply pouring molten metal into a mold. Achieving optimal results requires understanding its intricacies and leveraging key tips to maximize quality and efficiency.

In this article, we’ll explore the essential aspects of aluminium HPDC, including the stages of the process, its challenges, and expert tips to ensure success.

What Makes High Pressure Die Casting Unique?

HPDC is characterized by its fast, high-pressure injection of molten metal into a die cavity. For example, aluminium is heated to approximately 690°C—well above its melting point of 660°C—and then injected into the die at incredible speeds. The process is violent, with the molten metal filling the cavity in just 25 to 70 milliseconds. This rapid action ensures that the metal reaches even the smallest crevices, creating precise and detailed castings.

However, the speed and intensity of the process also demand stringent die design. Improperly vented dies can result in supersonic jets of fire or air entrapment, leading to defects. Additionally, maintaining consistent wall thickness and proper cooling cycles is crucial to avoid issues like porosity.

Top 5 Tips for Better Aluminium Die Casting

1. Avoid Prototype Tooling

Many assume that prototype tooling is a cost-effective way to test designs, but in HPDC, this simply does not work. Soft steel dies may produce a few hundred shots, but they are not durable enough for production. Instead, invest in high-quality DIN 1.2344 (H13) tool steel, hardened to 43–47 Rockwell. These production-grade dies can achieve up to 100,000 cycles or more with proper maintenance.

For early-stage prototyping, consider alternatives like sand casting, investment casting, or CNC machining. These methods are better suited for small quantities and allow for design refinements before committing to production dies.

2. Fill Large Holes Post-Casting

Designing with large holes or openings can obstruct the flow of molten aluminium, leading to air entrapment and weak spots in the casting. Instead, fill these holes during the casting process and remove them later through CNC machining. Modern machines like the Brother Speedio make post-machining fast and efficient.

This approach not only improves casting quality but also reduces the risk of defects caused by turbulence in the molten metal flow. Consistency in wall thickness—ideally between 2mm and 3mm—is another critical factor for successful die casting.

3. Use Generous Draft Angles

Draft angles are essential for ensuring smooth ejection of parts from the die. The standard recommendation is a minimum of 2° per side, but increasing this to 5° can significantly reduce wear and improve part quality.

Avoid designing parts without draft angles and relying on die makers to add them later. Modern 3D CAD tools make it simple to incorporate proper draft angles during the initial design phase, ensuring compatibility with the die casting process.

4. Add Three Leveling Pads

For parts requiring post-machining, include three leveling pads on the back side of the design. These pads act as reference points for clamping the part in fixtures, ensuring stability and preventing distortion during machining.

Referencing these pads in your GD&T (Geometric Dimensioning and Tolerancing) ensures accurate alignment and compliance with dimensional specifications. Proper fixturing is critical for high-quality machining results.

5. Stick to Common Aluminium Alloys

The most commonly used aluminium alloys for HPDC are ADC10 (A380) and ADC12 (A383). These alloys offer excellent strength, filling characteristics, and resistance to hot cracking. ADC12 is particularly popular in the U.S. for its superior performance in vacuum-assisted casting.

Using standard alloys not only simplifies the casting process but also ensures compatibility with industry norms and post-processing requirements. For more complex casting designs, explore options with OEM die casting parts.

Bonus Tip: Use a Trimming Die

Always insist on using a trimming die to remove overflows and gates from your casting. This ensures a clean finish without deforming the part. For low-production quantities, CNC machining can be used as an alternative for removing these excess materials.

See the Process in Action

To better understand the speed and precision of HPDC, watch this informative video showcasing the process:

High Pressure Die Casting is a powerful and versatile manufacturing process, but it requires careful planning and execution to achieve optimal results. By following these expert tips, you can ensure high-quality castings that meet your project’s requirements.