Which design principles we should adhere in mold draft angle

If the mold draft angle is not set, or if it is inadequate draft angles, it will often result in increased resistance to release, scratching the surface of the part, and keeping the part from deforming during release, thus affecting the quality of the part.

To make the molded parts ejected from the mold smoothly, the wall surface (including side cores and reinforcement ribs) in the same direction as the mold opening and closing must be set to facilitate mold release.

The size of the mold draft angle is related to the nature of the part, shrinkage rate, friction factor, wall thickness, and geometry of the part.

a. Hard plastics have a higher draft angle than soft plastics.

b. The molded parts with more complex shapes or more holes are taken to have a larger draft angle.

c. The height of plastic parts is larger and the hole is deeper, then take a smaller rdraft angle.

d. The wall thickness increases, the force of the inner hole wrapping tight core is large, draft angles slope should also be taken larger.

e. Sometimes, to keep the part in the concave mold or on the core when the mold is opened, the draft angle of the side is intentionally reduced or the draft angle is enlarged.

In addition, regardless of the convex and concave mold and the insert and even the slider should have a draft angle, usually, the mold draft angle is at least 0.5°, generally speaking, more than 1° is good, and its direction is based on the direction of the ejector rod or cylinder action of the machine. Especially when the concave die surface is etched, it is more important to pay attention to the mold draft angles.