Which of the following operations requires checking the coolant level?

Checking the coolant level is essential in all machining operations because coolant serves several critical functions that are beneficial across various processes. Coolants help to reduce heat generated by the friction between the tool and the workpiece, which is crucial in maintaining the integrity of both the tool and the material being machined. Proper coolant levels ensure effective cooling, which helps in preventing tool wear, and can prolong tool life.

Additionally, sufficient coolant helps to clear chips and debris from the cutting area, facilitating better visibility and improving cutting performance. This consideration applies whether one is engaged in turning operations, finishing operations, or drilling operations. Therefore, it is crucial to check the coolant level regularly to ensure optimal machining conditions, making it necessary for all types of machining operations.