KBM (knowledge-based machining (KBM)) can be incorporated into CAD/CAM systems at various levels. By comparing operations-based and process-based CAM systems to the automation capabilities offered by feature-based machining, there is a full range of capabilities afforded by KBM.

Operations-based CAM systems require the user to go through multiple steps to machine each part. The user must select which type of operation to use, select the machining boundary and the type of toolpath, then manually select tools, feeds and speeds and multiple machining options such as stepover distance and the incremental step in Z. These multiple steps must be repeated one at a time for every operation on a part, making it a time-consuming process that is prone to error. These systems offer little to no KBM.

Process-based CAM systems attempt to reduce these steps by grouping operations in standard processes.KBM is used as the program remembers the used processes and repeats them for future operations. However, this method only works when a shop uses the same processes over and over for the same types of parts.

When a process is applied to different types of parts, or parts made of different materials, the CNC programmer must still verify that the correct operations were used and that the correct tools, stepovers and speeds and feeds were selected because a static machining process does not automatically adapt to every part.

Feature-based CAM systems use a set of interrelated machinable features to describe a complete part. The beauty of features is that they not only describe shape, but these also are made up of one or more associative operations that describe the preferred method for cutting that shape at the NC machine.

A predefined set of machining rules and user preferences are applied to a part. KBM in these systems streamlines the manufacturing process by building the highest level of machining intelligence right into the CAM system. Machinable features contain information and rules describing how and where material removal should occur, cutting depths, whether to use climb cutting, whether to spot drill or center drill and preferred machining strategies for roughing and finishing.

The CAM system evaluates the part geometry and part material, selects the most appropriate tools and operations, recommends machining strategies, calculates feeds and speeds, then automatically generates the NC code.