What is Draft angle ?

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When someone asks me “what is draft angle?” or “why do I need a draft angle on my aluminum die casting part?” The technical answer is, all aluminum die castings require a draft angle on the walls of die cast parts perpendicular to the parting plane or parallel to the slide interfaces. Since I have selling die cast parts for over 10 years, I find simple answers and provide simple calculations for my customers. What does that mean to the typical engineer (any engineer other than tooling or mechanical) or professional buyer?

I try to give examples that most people can relate to, because most people do not have a need to concern themselves with how things are made, only what is made, and will it be what they need. I ask, “Have you ever noticed on a cupcake the bottom diameter is smaller that the top diameter?” or “Have you noticed that a cake pan has sides that slope in toward the middle of the pan?” That would be an extreme example of a draft angle. Aluminum die castings would stick inside the die casting tool, molds, or die casting die if there was not enough draft angle in the tool and part. The typical draft angle for an aluminum die casting part is two degrees per side. The calculation for that is simple if a person is familiar with die casting production part design, but is not familiar to most people.