Keyseat milling cutters, also known as Woodruff cutters, create keyseats in shafts for mating keyed parts to the shaft. The keyseat engages with the key on the part to prevent unwanted rotation of the part when it is mounted to the shaft. These milling cutters are each sized to create keyseats for a specific size of key. They can also be used to make slots in parts. Keyseat milling cutters are typically used on CNC machines in manufacturing and production facilities.