Part Details Review
Precise formulas for calculating proper draft angles do not exist. Experience has shown that a draft angle of 1° per side provides easy ejection of most smooth surfaces. Depth of draw, mold surface roughness, part complexity and the mold ejection system are some of the factors that influence the selection of draft angles. Also, material properties such as strength, rigidity, lubricity and shrinkage can also affect the amount of draft. Parts molded with high packing pressure and longer cooling times may experience additional difficulty during mold opening and part ejection.
A draft angle of 5° is recommended for the safe ejection of Apec high heat PC parts. On the lower side, 1/2° draft angles have been successfully used on many applications. The figure below shows some examples of parts with and without draft. Draft angles as low as 1/4° or less has also been used with special provisions. As the draft angles become smaller, mold surface finish becomes increasingly important. When using smaller draft angles, ensure that the core and the cavity are polished in the direction of mold opening.