A collet is a clamping device that is used to hold an geometrical object in a machine tool, such as Lathe, Milling, Grinding machine etc., Generally there are two type of Collets namely WORK Holding & TOOL Holding. In each type there are different sub types of collets viz., Dead Length (F-Type) Collets, ER (Type-E) collets, W, B. L-type collets that are generally used for holding the work or Tool while performing a machining operation.
It consists of a cylindrically ground shank and tapered cone with 3 or 4 equally spaced slits that runs through until cylindrical shank. This cylindrical shank and cone fits inside a matching tapered outer sleeve. When the outer sleeve is moved axially the force applied on the cone & the petals clamps the Tool / Object. This allows the collet to securely hold the object in place while machining or other operations are performed on it.
With a dead-length chuck, the collet is fixed to the chuck body, and a tapered sleeve pushes forward over the collet to compress it . Because there is no axial movement of the collet with this design, workpiece positioning remains secured.