Ensure you are wearing appropriate safety gear, including gloves and goggles, before using the rotary tool metal cutting disc wheel. Insert the mandrel into the rotary tool's chuck securely. Attach the cutting disc to the mandrel, ensuring it is properly aligned. Adjust the rotary tool to the desired speed and apply gentle pressure to the material you intend to cut. Let the cutting wheel do the work, avoiding excessive force which may cause the wheel to break. After use, turn off the rotary tool and allow the cutting disc to come to a complete stop before removing it from the mandrel. Dispose of any worn or damaged cutting discs properly and store the remaining discs and mandrels in a safe place for future use.