Milling

Milling is a machining process that uses a rotating cutting tool to remove material from a workpiece, creating flat, curved, or complex surfaces. The tool advances against the workpiece to shear off small chips. Milling is a central method in subtractive manufacturing and is used with metals, plastics, and composites. The term also refers to the processing of grains into flour or meal.

In manufacturing, milling is performed on milling machines, including vertical and horizontal types and computer numerical control (CNC) variants. Vertical mills position the spindle above the workpiece; horizontal mills use a sideways spindle. Modern CNC mills can execute three- to five-axis moves to reproduce complex geometries. Common operations include face milling, end milling, slotting, contouring, drilling, and tapping.

Tooling and process parameters: cutting tools are typically end mills or face mills made of carbide or high-speed steel, with varying flute counts and coatings. Tool geometry, spindle speed, feed rate, and depth of cut are selected to balance material removal, surface finish, and tool life. Coolants or air flows help manage heat and chip evacuation.

Grain milling refers to processing cereals into flour and related products. Early milling relied on stone, wind, or water power; modern mills use roller mills, hammer mills, and sifters to separate and grind grain into flour, meal, and bran, with emphasis on efficiency, product consistency, and contamination control.