In the modern manufacturing landscape, aluminum die casting stands as the premier process for producing lightweight, high-strength, and dimensionally complex components. From the intricate housings of 5G telecommunications equipment to the structural chassis of next-generation electric vehicles, the success of a product is often decided at the drafting board. However, designing for die casting is fundamentally different from designing for CNC machining or 3D printing. It requires a deep understanding of fluid dynamics, thermal contraction, and mechanical ejection. A failure to optimize the design for the casting process—known as Design for Manufacturing (DFM)—results in high scrap rates, expensive tooling modifications, and compromised part integrity.
The most common pitfalls in aluminum die casting design stem from a misunderstanding of how molten metal solidifies and how the finished part exits the steel mold. In the high-pressure environment of a die casting machine, the metal is injected at high velocities, and the speed at which it cools dictates everything from the part’s surface finish to its internal porosity.
The “Golden Rule” of die casting is to maintain a uniform wall thickness throughout the component. In a die casting mold, thinner sections solidify faster than thicker ones. If a design features a heavy boss connected to a thin rib, the thin section will freeze first, cutting off the flow of molten metal to the thicker area. This leads to “Shrinkage Porosity,” where the center of the thick section becomes a hollow void as the metal contracts.
A die casting mold is a rigid steel structure. Unlike a sand mold that is broken away, a die must be opened and the part must be pushed out. Draft angles are the slight tapers applied to all vertical surfaces parallel to the direction of the tool’s opening. Without sufficient draft, the aluminum will “gall” or scrape against the steel as it contracts during cooling.
Once the basic geometry is established, the design engineer must focus on “Advanced Structural Optimization.” This phase involves reinforcing the part without adding unnecessary weight and ensuring that the molten aluminum reaches the furthest extremities of the mold without losing temperature or introducing turbulence.
Instead of increasing wall thickness to gain strength, engineers should utilize Ribs. Ribs act as “highways” for molten metal, allowing it to flow into distant cavities while providing structural rigidity to the part.
In die casting, sharp corners are the enemy of both the part and the tool. Molten metal does not like to turn 90-degree corners; doing so creates turbulence and traps air.
Use this table as a quick reference for the standard tolerances and design limits in modern high-pressure aluminum die casting.
| Design Feature | Recommended Minimum | Ideal Range | Impact on Quality |
|---|---|---|---|
| Wall Thickness | 1.0 mm | 2.0 mm - 3.5 mm | Reduces Porosity & Cycle Time |
| Draft Angle (Outer) | 0.5° | 1.0° - 2.0° | Prevents Surface Dragging |
| Draft Angle (Inner) | 1.0° | 2.0° - 3.0° | Ensures Easy Ejection |
| Fillet Radius | 0.5 mm | 1.5 x Wall Thickness | Eliminates Stress Cracks |
| Standard Tolerance | ± 0.1 mm | ± 0.2 mm | Governs Fit and Assembly |
| Ejector Pin Dia. | 3.0 mm | 6.0 mm - 10.0 mm | Prevents Part Distortion |
ADC12 (A383) is the most common choice due to its excellent fluidity and resistance to hot cracking. For applications requiring higher corrosion resistance, A360 is preferred, though it is slightly more difficult to cast.
Yes, but they require “Side Actions” or “Slides” in the mold. This significantly increases the complexity and cost of the tooling. Whenever possible, it is best to “design out” undercuts to maintain a simple two-plate mold configuration.
All die castings have some degree of internal porosity due to trapped air or metal shrinkage. If your part requires pressure tightness (like a fuel pump) or high-strength structural loads, you must design for “Vacuum Die Casting” or specify critical zones where porosity is strictly controlled.
русский
日本語