To create a milling NC sequence, you have to define geometry that you want to mill. Creo NC provides several tools that let you define mill geometry as a separate feature, and then use this definition repeatedly for various NC sequences within the manufacturing model.

The simplest way to define geometry for a Face, Volume or a 3-Axis Conventional milling NC sequence is by using a Mill Window, that is, by sketching or selecting a closed contour. The geometry inside the mill window gets machined. Mill Windows are separate features that can be created at setup time, as well as at the time of defining an NC sequence.

Another way to define a Volume NC sequence is a Mill Volume. This is the volume to be removed during an NC sequence. The tool will always be within the Mill Volume, that is, by default the tool can not penetrate any surfaces of the volume, except its top surfaces (at the time of creating an NC sequence, you can also explicitly specify side surfaces of a Mill Volume that can be violated during tool approach and exit). To define the Mill Volume, you can reference geometry of design model, sketch volume to be machined or excluded, intersect the volume with the workpiece or reference model, offset surfaces (for example, by tool radius). This set of tools can be used in any combinations to define a single Mill Volume.

You can also select surfaces from a Mill Volume when defining other types of milling NC sequences (Surface milling, Facing, Profiling, and Pocketing).

When you merge and trim mill geometry in the manufacturing geometry definition mode, you are warned when a manufacturing quilt will be consumed and certain actions are not available.

Another tool for defining a milling NC sequence is creating a Mill Surface. This is a user-defined surface quilt that can be referenced by Surface milling NC sequences or by Mill Volumes.