The difference between turning and milling processes

2026-08-01 11:22:19

In the field of precision machinery manufacturing, turning and milling are the two core basic processes in CNC machining, which almost support the forming of the vast majority of metal and non-metal parts. Many people tend to confuse the boundary between the two when choosing a tool: why do shaft parts default to turning while sheet metal and cavity parts must be milled when both tools remove material? The fundamental difference lies in the core logic of "who will rotate" - turning involves workpiece rotation and tool feed, while milling involves tool rotation and workpiece feed. The different motion subjects directly determine the vastly different processing objects, precision characteristics, efficiency costs, and applicable scenarios between the two.

The core boundary between the two processes lies in the load-bearing object of the main motion. The main motion is the core motion that provides cutting power and achieves material removal, directly determining the forming principle of the part.

1. Turning machining: The workpiece rotates as the main motion, and the tool performs feed motion

The core logic of turning is rotary forming: the workpiece is clamped on the lathe spindle for high-speed rotation, and the turning tool performs feed motion along the axial, radial, or specific trajectory. Through continuous cutting of the tool tip, the workpiece is machined into a rotating body shape.

Main motion: the rotational motion of the workpiece, providing cutting line speed;

Feed motion: The straight or curved movement of the cutting tool controls the cutting depth and tool path;

Forming principle: All machined surfaces are formed around the axis of rotation of the workpiece, naturally possessing rotational symmetry.

Turning is a process where the workpiece rotates and the knife moves, suitable for machining all parts that are symmetrically rotated around the central axis.

2. Milling: The tool rotates as the main motion, while the workpiece undergoes feed motion

The core logic of milling is multi blade cutting forming: the milling cutter is clamped on the spindle of the machine tool and rotates at high speed. The workpiece is fed along the X, Y, and Z axes through the worktable, and the rotating multi tooth blade removes material layer by layer, forming structures such as planes, grooves, cavities, and surfaces.

Main motion: The rotational motion of the milling cutter provides cutting line speed;

Feed motion: The multi axis linkage movement of the workpiece controls the machining position and contour trajectory;

Forming principle: By combining the tool contour and cutting path, it can process any asymmetric and complex shape.

Simply put, milling is a process of "turning the knife and moving the workpiece", suitable for processing non rotating structures such as flat surfaces, irregular surfaces, and cavities.