Drilling

Drilling uses a two-flute rotating tool to create cylindrical holes in a solid workpiece, typically the first operation in a sequence of CNC machining operations that may include reaming, boring, tapping, or other secondary hole finishing operations. Drill sizes range from tiny micro-drills under 0.1 inches to large multi-inch drills, with selection based on hole size, depth, material, and required tolerance.

CNC machining centers perform drilling using programmable coordinates, ensuring hole location accuracy and repeatability that manual drilling cannot match, making CNC drilling essential for multi-hole assemblies where concentricity and location matter. After drilling, holes often require secondary operations like reaming for size control, countersinking or counterboring for fastener accommodation, or tapping for threads.

High spindle speeds and careful coolant application are critical for drill performance, and chips must be evacuated efficiently to prevent drill breakage.