ER25

ER25 refers to a specific size of tool holder collet. Collets are essential components in machining operations, particularly with CNC machines and milling machines. They are designed to hold and tighten around a cutting tool or a workpiece. The ER collet system is a widely used standard in the manufacturing industry due to its precision and versatility.

The "ER" designation in ER25 stands for "Einsatzspannfutter-Rund," which translates from German to "insert chuck round." The "25" indicates the nominal clamping diameter of the collet in millimeters. Specifically, an ER25 collet can accommodate tools with diameters ranging from 1.5 mm to 25 mm. The actual clamping range for a specific ER25 collet is typically divided into several sub-sizes, with each collet designed to grip a particular range of diameters within the overall 1.5-25 mm spectrum.

ER collets work by being inserted into a mating collet chuck or spindle. When the nut on the collet chuck is tightened, it draws the collet into a tapered seat, causing the collet's segmented jaws to contract and securely grip the tool shank. This mechanism provides a high degree of concentricity and rigidity, which is crucial for achieving accurate machining results and minimizing tool runout. ER25 collets are commonly found in milling machines, lathes, and router machines for holding various cutting tools like end mills, drills, and boring bars.