物件的外形，為了迎合人體學、與美觀等因素的需求，現在常會採用自由曲面。而傳統判斷可否脫模的方法，無法有效的應用在自由曲面的物件上。本文提出一個簡捷的方法，既可判斷規則形狀、也可以判斷自由曲面的物件可否脫模。而它的結果，更可用來求取此物件的脫模角錐。脫模角錐雖然是物件脫模方向最確切的描述，但是並不適合用在一般的描述上。本文從脫模角錐求出其內切圓錐，也就是脫模圓錐，因其紙包含一軸向和一個脫模角，在描述脫模範圍時，很容易一目了然。

Free-form surfaces are frequently used to consider the ergonomic and
esthetic factors. The traditional methods for partibility can’t be efficiently applied to objects with free-form surfaces. An efficient method is proposed in this paper that can get partibility results for either regular or free-form surface objects. Furthermore, the parting pyramid can be found from the results of our method. Although the parting pyramid is the exact description of parting directions, it is not suitable for common usage. Our method finds an inscribed cone from the parting pyramid, i.e., the parting cone. This cone only includes an axis and a parting angle. The parting cone is easily visualized for describing the parting directions of an object.