Question 221General Subjects - QMED

The correct answer is D) tap the holes without cutting oil. When hand tapping holes in cast iron, it is generally not recommended to use cutting oil. Cast iron is a hard, brittle material, and the use of cutting oil can actually increase the likelihood of the tap breaking or the material cracking during the tapping process. Instead, tapping cast iron holes without any lubricant is the preferred method, as the friction and heat generated during the tapping process can help to clean and smooth the hole walls. The other options are incorrect because: A) starting with a plug tap is not necessary for hand tapping, B) chamfering the edges is not required, and C) flooding the tap with mineral oil is not recommended for cast iron.