The gradient made on the cavity or the core to make removal of parts from the mold smoother.
Draft angle normally requires 1 – 2 degrees, but it depends on the material and molding shape, or whether a texture process (the process to make the surface a little rough) is done.
In injection molding, because molten plastics will shrink after molding, make as small a draft angle as possible on the cavity side, and a large angle on the core (insert) side.
Because crystalline plastics has high mold shrinkage, it shrinks into the inside of the mold on the cavity side, which makes removal smooth, whereas it adheres to the mold on the core (insert) side, which makes removal difficult. Therefore, to make a draft angle, you will need to take the adhesion to the core (insert) side in consideration.
On the other hand, amorphous plastics has low mold shrinkage and hardly shrinks to the inside. Therefore, a draft angle on the cavity side is made as large as the one on the core (insert) side.
