Draft Angles
Draft is a primary consideration on part design and it depends upon whether the mold is a male or female mold. Draft is required to free parts from molds. Female mold draft angles are 0° to 2°, with an average about 1°. In some cases since the plastic is likely to shrink away from the female mold as it is cooling, you don’t need any draft at all. Female mold draft angles for crystalline polymers are less than those for amorphous polymers.
Typical male mold draft angles are 1° to 5°, with an average of about 4°. If the part is not very tall, say one to two inches high, it is possible to have as little as 2° draft. However, if your part is about eight to ten inches tall then you will probably need a minimum of 5° draft. Male mold draft angles for crystalline polymers should be greater than those for amorphous polymers.
Draft angles are increased 1° for every 0.2 mils (0.0002 in or 5 μm) of texture depth. Less draft increases the chance of damaging the part during ejection. Additionally, molders may have to apply mold release or special mold surface coating or treatment, ultimately leading to very long cycle times and higher part costs.
