Why Draft Angles Matter in Die Casting—and How to Design Them Right

A common mistake in die-cast part design is underestimating the importance of draft angles—the slight tapers built into vertical walls to allow the part to be ejected cleanly from the die.

Even a perfectly filled and cooled casting can be damaged if it sticks in the mold or drags during ejection. That’s why draft is essential.

📐 What Is Draft?

Draft is the angle applied to vertical surfaces, usually measured in degrees. It facilitates the release of the part from the die cavity or core without causing scratches, drag marks, or distortion.

📏 Typical Draft Guidelines:

• Exterior walls (die side): 1.0°–1.5°

• Interior features (cores/ejector side): 1.5°–2.5°

• Zinc alloys: Lower draft maybe acceptable (as low as 0.5°) due to better flow

• Aluminium alloys: Require more draft to buffer/accommodate shrinkage behavior

🔧 What Happens If You Skip Draft?

• Ejection damage

• Excessive flash

• Tool wear and fatigue

• Poor surface finish on vertical walls

• Need for unnecessary secondary machining

At LVIO Precision, we perform DFM reviews on every casting project to ensure proper draft is included—particularly on deep ribs, bosses, or complex wall features.

If the part is already designed without draft, we can propose manufacturable adjustments that reduce tooling complexity and improve yield.

Don’t overlook this small design feature—it has a big impact on part quality, cost, and tooling life.