In most applications, feature technology and feature recognition are utilities intended to improve the programming performance for simple geometry like holes and pockets. In many systems, this may be limited to 2-D machining.

Granted, most machining applications have only basic requirements so this solution is often sufficient. Can feature technology apply to broader applications and more complex geometry?
Within integrated CAD/CAM processes, geometry features may be identified during the design step and automatically passed into the CAM environment. These features may be retained as corporate knowledge in a database of commonly used components and dimensions. However, most companies that produce molds and tooling are smaller supplier companies and receive CAD data from their customers. The suppliers often do not have a corporate enterprise system and generally use independent CAM software products from their customers. How do features work in these environments?
Of course, if the supplier has the same CAM software as the customer’s CAD system or has a direct translator, then the native CAD data can be imported. In some cases, the design feature information also is imported directly into the CAM system.
But in the general case, the CAM system must be able to create the feature information even if the data originates with neutral data such as STEP or IGES, without having intimate knowledge of the original design. In such a feature recognition process, the CAM software is able to recapture the feature information that was in the original design, or create it for the first time.
Breaking It Down Further
Yes, features are holes and pockets. But features also can be thought of in a more general way as any repeated geometry element or entity with a similar function. Features are a way to organize and add intelligence to CAD models. As models increase in size and complexity, the added organization can be extremely valuable. A feature can be a simple hole or a complex hole with multiple surface steps (counter-sink, clearance, chamfer, etc.), with threads, as a through hole or blind hole, a hole having orientation, or more.
And if a model has hundreds of holes, then the feature recognition and data organization can save the user from hours of laborious programming time and hundreds of error-proned selections. Similarly, pockets can have many descriptive parameters, such as open, closed, and corner and fillet radii.
These added descriptors begin to open the possibility that features can do more than identify geometry in a model. With this added information, you also can associate machining process knowledge to the features and then apply it to the actual geometry. These added levels of abstraction may seem like extra work, but the return is measured by reducing long selections or identifying a missed hole after the block is off the machine. There also is added consistency to the machining process by reusing the captured feature knowledge and process macros on future jobs.
How do you machine a blind hole or a through hole? How do you enter into an open pocket or a closed pocket, or machine multiple ribs and pockets that have different orientation or require five-axis machining approaches? By storing the machining processes in a macro database, the data is easily retrieved, whether by the same user or a different user. This approach allows for standards within an organization and greatly facilitates a low-risk way to introduce an apprentice or new programmer to the manufacturing environment.
Traditional sort and filter database functions allow large sets of process macros to be quite manageable. Depending on applications, macros can be organized by milling machine (standard or high-speed process), material (aluminum or steel) and various dimensions. And the database approach is scalable—working well with only a few stored macros or when large amounts of process knowledge are captured.
What is interesting about this approach is that each customer is storing their own local machining process knowledge—feedrates, step-downs, etc. The user gets the benefit of using productive CAM software as well as adding personal skills and experiences, including capabilities of manufacturing equipment, to further improve the performance of the system.