End Mill

An end mill is a multi-flute rotating cutting tool that performs most of the operations in CNC milling, profiling part outlines, milling pockets and slots, facing flat surfaces, plunging vertically into material, and producing curved surfaces. End mills are available in numerous geometries optimized for different applications: square end mills for sharp internal corners, corner-radius mills for faster cuts and improved tool life, and ball-nose mills for smooth 3D contours.

The flute count, diameter, material (carbide or high-speed steel), and coating determine a tool's performance envelope and cost, with coated carbide tools offering longer life and higher speeds compared to uncoated tools. Programmers select end mill size strategically, larger tools cut faster and produce better finish, while smaller tools are necessary for tight corners and small features.

An effective CNC machining program might use a rough end mill for stock removal, then a finish end mill for dimensional accuracy and surface quality, minimizing cycle time while meeting all engineering requirements.