Question 652General Subjects - Assistant Engineer

The correct answer is C) Aluminum. Aluminum can be drilled at the highest speed compared to the other materials listed. This is because aluminum is a relatively soft metal that is easy to machine and drill. It has a lower melting point and lower hardness than the other materials, which allows it to be drilled at higher speeds without overheating or damaging the drill bit. In contrast, copper, high carbon steel, and medium cast iron are all harder materials that require slower drilling speeds to avoid excessive wear on the drill bit and potential damage to the workpiece.