What is the draft angle for closed die forging?

The draft angle in closed die forging refers to the slight taper (or angle) applied to the surfaces of the die cavities to facilitate the easy removal of the forged part after it has been formed. The draft angle ensures that the part can be ejected from the die without getting stuck or causing excessive wear on the die surfaces.

Typical Draft Angles:

• Range: For closed die forging, the draft angle typically ranges between 1° and 5° (with 2° to 3° being common).

• Factors Influencing Draft Angle:

• Material: Softer materials (e.g., aluminum) may require a smaller draft angle compared to harder materials (e.g., steel).

• Part Geometry: Parts with more complex shapes or deeper cavities often require a larger draft angle to ensure smooth ejection.

• Die Design: If the die surfaces have intricate features or undercuts, a larger draft angle may be needed to prevent the part from becoming stuck in the die.

Why is Draft Angle Important?

• Facilitates Ejection: The draft angle reduces the friction between the forged part and the die, making it easier to remove the part without damaging either the part or the die.

• Prevents Damage: A proper draft angle prevents the forging from becoming wedged in the die, which could lead to misalignment or damage to the tooling.

• Improves Tool Life: It helps in reducing wear and tear on the die surfaces by minimizing friction during the ejection process.

How to Determine the Draft Angle:

• The draft angle is generally specified during the design phase of the die and part geometry. It should be as small as possible while still ensuring easy part ejection and die longevity.

In summary, the draft angle in closed die forging is a critical feature of die design, usually ranging from 1° to 5°, depending on the material, part complexity, and the desired ease of ejection.