Collet is a critical clamping device used in CNC machinery to secure cutting tools or workpieces. It is commonly found in equipment such as drilling and milling machines, machining centers, and turn-mill centers. Its primary function is to hold the cutting tool accurately and steadily, ensuring precision and efficiency in the machining process. The collet operates based on its precise elastic deformation structure—typically made of high-quality spring steel—which, under the axial pressure applied by an external nut, contracts inward evenly to generate a strong clamping force on the tool shank. This design offers simple and quick clamping operation and provides good adaptability, as it does not require extremely tight manufacturing tolerances for the tool shank.

As one of the most essential components of the tool holder system, the collet plays an irreplaceable role in modern high-efficiency machining. It is particularly suitable for high-speed cutting applications, maintaining reliable clamping rigidity and dynamic balance even at tens of thousands of revolutions per minute. The clamping action is achieved by an accompanying locking nut: the user rotates the nut to apply preload force, causing uniform elastic deformation of the collet and ultimately enabling high-concentricity clamping of the tool.

The clamping accuracy of a collet is a key performance indicator, generally ranging from 0.001 mm to 0.008 mm. This precision grade directly affects the total indicator runout (TIR) after the tool is clamped, which in turn determines the final machining quality of the workpiece. Therefore, during selection, it is essential to consider the requirements of the specific machining process: standard precision collets can be used for general roughing and semi-finishing, while ultra-high-precision collets must be chosen for ultra-precision cutting applications such as precision mold cavity machining and micro-drilling. The shape error and surface quality of the tool connection section also significantly influence the final accuracy of the entire clamping system.

Furthermore, collets come in various specifications and clamping ranges, with common types including ER, SK, and DA. Among these, ER collets are the most widely used due to their broad clamping range and strong compatibility. Proper selection, installation, and maintenance of collets—along with regular inspection of their clamping force and wear status—are crucial for extending their service life and maintaining the machining accuracy of the equipment. In summary, though small in size, the collet is a fundamental component that enables high-precision and high-efficiency machining in CNC applications.