What rotates on a milling machine?

• A. Material/workpiece
• B. Cutting tool
• C. Spindle
• D. Cutting tool and spindle

Answer: (D)

In milling, material removal is done by a rotating cutter that is mounted in the machine’s spindle. The spindle is the rotating drive that powers the cutting tool, so the tool spins as it engages the workpiece. In most milling operations the workpiece is clamped and fed past the rotating cutter rather than being rotated itself, unless you’re using a rotary table or special setup. That combination—the rotating cutting tool driven by the spindle—captures what actually rotates on a milling machine, so both the cutting tool and the spindle are rotating.