Milling Tools

At its most basic, milling is the meeting of a rotating tool with a clamped and stationary workpiece, as opposed to turning where the tool is stationary and the work material rotates. Actually, the workpiece has feed motion imparted from the machine tool. The meeting of the rotary motion of the cutter and the cutting edge of the tools produces fluctuating cutting forces: vibration, heat, and, if all goes well, chips.

Source: A New Milling 101: What Milling Is, Then and Now (Plus a Glossary of Milling Terms)

Milling machines may have either vertical or horizontal spindle orientation, and typically, face milling cuts flat surfaces, but multi-axis CNC machines make it possible to include three-dimensional movements. That said, there are four basic categories of milling: face milling, periphery milling, slot milling, and specialty applications.

Source: A New Milling 101: What Milling Is, Then and Now (Plus a Glossary of Milling Terms)

Face milling: Used for creating a flat surface (face) on the workpiece. The cutting plane is usually perpendicular to the axis of rotation and the cutters most often feature a single row of inserts, designed with a wide range of cutting geometries, inserts, lead angles, and mounting adaptations.

Periphery milling: Generates a primary surface parallel to the spindle rotation. A secondary surface is sometimes produced. The cutting plane is usually parallel to the axis of rotation.

Slot milling: Used for producing a slot or channel in the workpiece. There are two primary types of slot milling cutters: disk mills and end mills. Disk mills can be high-speed steel, brazed carbide, and indexable-insert-based. They are typically used in operations perpendicular to the spindle rotation.

Specialty applications: Includes copy milling, plunge milling, ramping, helical and circular interpolation, trochoidal, and others.

Source: A New Milling 101: What Milling Is, Then and Now (Plus a Glossary of Milling Terms)