What does depth of cut mean in milling?

• A. The distance from datums to a feature
• B. The speed of the cutter
• C. The geometry of tool holder
• D. The thickness of material removed in a single pass

Answer: (D)

The depth of cut in milling is how far the cutter penetrates into the workpiece in one pass—the thickness of material removed during that pass. It’s the amount of metal the cutter takes away each time it engages the work, and it directly affects cutting forces, heat, and tool wear. A larger depth removes more material per pass but increases load on the tool and machine, raising the risk of chatter or breakage; a smaller depth reduces those risks but takes more passes to achieve the same total removal. This is different from the speed of the cutter or the geometry of the tool holder, and it’s not about datum positions. In milling, depth of cut is typically the axial dimension of material removed per pass, while the width of cut is a separate, radial consideration.