ABSTRACT
A feature can be defined either as a section of a part, which possesses some manufacturing specifications [1], or a geometric shape, which can be utilized in computer-aided design (CAD) [2]. In fact, a functional entity (object, shape, or process), which is meaningful in a certain domain (for example, a fastener in assembly, a shaft in design, or a groove in machining), [3] represents a feature. Broadly speaking, a feature can also be defined as an entity that represents a general shape such as holes, pockets, slots, ribs, or bosses, achieved through a manufacturing operation on the raw stock [4,5]. The word “features” indicates several meanings in different contexts [4]. For example, in design, it refers to a web, or an aerofoil section, while in manufacturing, it refers to the slots, holes, and pockets, while in inspection it is used as a datum or reference on the part. The features can be classified as shape features, manufacturing features, assembly features, and geometric features depending on their application requirements [6-9]. Moreover, the features can be additive such as bosses and
webs, as well as subtractive such as holes and slots. The different features can be categorized as follows [10,11]:
◾ Form features represent portions of nominal geometry ◾ Tolerance features provide deviations from nominal form/ size/location
◾ Assembly features can be considered as a collection of various features types to define assembly relations, such as mating conditions, part relative position and orientation, various kinds of fits, and kinematic relations
◾ Functional features represent sets of features related to specific function. It includes design intent, nongeometric parameters related to function, performance, etc.
