Correct option is C
In the machining of
cast iron, typically
no coolant is required due to the self-lubricating properties of cast iron. Cast iron contains a high percentage of free graphite, which acts as a natural lubricant during machining. The presence of graphite reduces friction and heat generation, making it possible to machine cast iron without the need for additional coolants in many cases.
Moreover, applying coolant can create issues such as the formation of sludge when coolant reacts with the fine cast iron chips (dust), leading to clogging or disposal problems.
