A feature, in computer-aided design (CAD), usually refers to a region of a part with some interesting geometric or topological properties.
[1] The first published work on features was for the original boundary representation modelling system, BUILD, and was performed by Lyc Kyprianou.
In design-by-features, also known as feature-based design (FBD), feature structures are introduced directly into a model using particular operations or by sewing in shapes.
They define domain independent form feature as a set of faces with distinct topological and geometric characteristics.
They have modelled creation of a form feature as addition/subtraction of feature-solid (exact minimum volume required) to/from based-solid.
They have developed a feature recognition algorithm based on the concept of computing dynamic topological status of faces.
Kyprianou's work was continued and extended by Jared et al. to cover a number of important special cases where features interacted.
Automatic Feature Recognition (AFR) is regarded as an ideal solution to automate design and manufacturing processes.
The most common methods according to Han et al. range from graph-based algorithms to hint-based and volumetric decomposition techniques.
In the graph-based feature recognition, a graph showing the topology of the part (connection of faces) is created.
They fail to account for manufacturability of the recognized features due to their strong reliance on topological patterns rather than geometry.
For example, presence of two opposing planar faces is a hint for potential existence of a slot feature.
However, the efficiency of the approach has been argued, as there could be a huge number of traces that won't lead to valid features.
[17][18] Other existing FR approaches are volumetric decomposition,[19][20] Artificial Neural Networks,[21] and expert systems[22] Babic et al.[23] briefly introduces many of them.
However, building feature recognition systems that function effectively on real industrial products has been elusive.
A real product with hundreds of faces and end edges brings almost all the above approaches to a halt due to computational complexity.
Graph representations, hint definitions or volume decompositions are much more difficult to define for 3D and free form features.
Some of these issues such as the presence of filleted edges and free form surfaces in the model have been studied by Rahmani and Arezoo.
Manufacturing feature recognition library provides recognition of manufacturing features such as simple holes, tapered holes, counter-bore holes, counter-sunk holes, counter-drilled holes, hole-chains, hole patterns such as linear, rectangular and circular patterns, fillets, chamfers, blind pockets, through pockets, drafted pockets, filleted and chamfered pockets, simple slots, drafted slots, filleted and chamfered slots, islands in pockets and slots, machinable volumes, machinable slabs, multiple intersecting features, axi-symmetric features such as external turned profiles, internal turned profiles, turned grooves such as vee and dovetail grooves, and mill-turn features such as slots and pocket in turned profiles.