Interpolator in a CNC machine

The correct option is coordinates axes movements.

In a Computer Numerical Control (CNC) system, the controller must translate high-level program instructions (like straight lines or arcs specified in G-code) into physical motion along the machine's coordinate axes (such as X, Y, and Z).
The tool path is rarely aligned with just a single axis; most operations require simultaneous movements of multiple axes to achieve the desired path (contouring).

The interpolator is the hardware or software unit within the CNC controller that performs this coordination. It calculates the intermediate coordinate points along the programmed path at extremely small time intervals.
By doing so, it generates coordinated velocity and position commands for each axis drive motor simultaneously, ensuring that the cutter follows the exact programmed geometric path (linear, circular, or helical) at the specified feed rate.

Let's examine why the other options are incorrect:
1. controls spindle speed: Spindle speed control is managed by the spindle drive controller, not the interpolator.
2. operates tool changer: Automatic tool changing is a sequential auxiliary function typically controlled by a Programmable Logic Controller (PLC).
3. commands canned cycle: Canned cycles are pre-programmed subroutines executed by the CNC interpreter to simplify programming, not by the real-time path interpolator.