In CNC machining, what does the Z-axis typically control?

The Z-axis in CNC machining primarily controls the vertical depth of the cutting tool. This movement is crucial because it allows the cutting tool to approach or retract from the workpiece along the vertical plane, enabling precise cuts at varying depths. The Z-axis is essential when machining components that require different layer heights or engaging in processes like drilling, milling, or grinding, where the position of the tool relative to the workpiece's surface must be adjusted accurately.

In contrast, the other options pertain to different axes or functions in CNC operations. The left-right movement of the machine is controlled by the X-axis, while the speed of the cutting process is managed by spindle speed settings, not an axis. Lastly, the rotation angle of the workpiece involves the use of additional rotary axes, often referred to in setups that require angular positioning, which is distinct from the vertical movements governed by the Z-axis.