DIAGNOSIS: That's usually the auger—the corkscrew that moves the ice—grinding against something, either a frozen-over evaporator or a foreign object.
FIX: Unplug the machine immediately. Open the ice bin and look inside the ice chute. Use a flashlight to see if there's a piece of ice jammed in the auger or if you can see any obvious obstruction. If you see something, try to carefully remove it with long tweezers or pliers (not your fingers).
IF THAT DIDN'T WORK: The evaporator coil is likely frozen solid around the auger. You'll need a full manual defrost. Unplug, empty the bin and water reservoir, and let the unit sit warm and open for at least 24 hours. Then plug it back in and start a clean cycle.
HEADS UP: Don't force it or keep it plugged in when it makes this noise. You can permanently damage the auger motor. If it's frozen, the 24-hour thaw is non-negotiable.