Base feature of castings
This forms the base or the central foundation of every casting. This defines the overall shape of the casting. It can be expressed in terms of the minimum-volume shape that completely encloses the casting after removing small projections (like bosses) and filling up small depressions (like holes). The shape can be a rectangular block, cylinder, sphere, hemisphere, torus, spiral, L-bracket, wheel, etc. It can be solid or hollow.
Local feature of castings
This type of casting builds on base casting. It is used to design depressions in the form of holes and slots on the surface. On the other local feature casting can also take the form of protrusions such as bosses and ribs on the base surface. Consequently the metal cast may resemble a simplistic design of a circle or rectangle. In other cases, it may be intricate and complicating based on the lines of a loop or an ellipse forming a circle or an oval. The design may be straight or oval in shape, not at all perpendicular to the surface.
Tooling feature of castings
Tooling is a process of connection. Tooling is basically the method used to connect base and local features to develop and form patterns, molds, core boxes, undercuts, parting lines, core support systems and ingates. Tooling can also be used to create runners, sprues, feeders, feeder necks and various feed aids, which are chilled, insulated and exothermic in nature.
Connecting feature and modifier Connecting features are those in between adjacent features or those connecting two or more features, such as taper, chamfer, fillet and wall between two holes. Feature modifier implies a minor modification to the standard shape of a single feature using draft, chamfer, fillet, etc.