The precision double cone collet is used primarily in industrial applications for holding cylindrical workpieces or tools on machine tools such as CNC lathes, grinding machines, automatic machining centers and quick-change tool systems. Its unique geometry ensures high centering accuracy and uniform clamping force, making it ideal for high-speed machining and tight tolerances.

The collet has two opposing conical surfaces that interact with corresponding conical surfaces of the spindle or clamping device. In the center is a cylindrical or slightly conical hole, often with a standard taper such as Morse or ISO, for inserting the workpiece or tool. The radial cuts, usually three or six in number, allow the collet to deform elastically, adapting to the diameter of the component and evenly distributing the clamping pressure.

The collet is housed between two clamping cones, typically part of the spindle or clamping system. By applying an axial force, via a nut, pneumatic actuator, hydraulic actuator or lever system, the cones push the collet radially inwards. The radial cuts allow the collet to shrink uniformly, clamping the piece or tool with high gripping force.

The symmetry of the system guarantees automatic centering with precision in the order of a few microns, essential for high-speed machining where imbalances would cause vibrations and inaccuracies. By reducing the axial pressure, the collet returns to its original shape thanks to its elasticity or with the aid of return springs.

Fields of application, CNC lathes, the biconical collet is used for the rapid clamping of bars, ensuring a reduction in runout and precision finishing. In grinding machines, it ensures perfect centering for machining with micrometric tolerances. In machining centers, it is ideal for high-speed milling thanks to its dynamic stability. In rapid tool change systems, it facilitates the replacement of tools in automated contexts, often in combination with ER collet type systems.

The advantages compared to other clamping systems are the centering precision, with eccentricity often less than 0.005 mm, minimizing machining errors. The high rigidity reduces vibrations in high-revolution machining, while the versatility allows use with a wide range of diameters thanks to the flexibility of the radial cuts. The speed of change makes it suitable for series production and automation, while the materials resistant to wear and cyclic fatigue guarantee its durability.

The effectiveness of the system depends on the quality of the conical surface, where imperfections can compromise precision. It is not suitable for high axial loads, for which positive interlocking systems such as hydraulic chucks are preferable. Periodic maintenance is necessary to control the wear of the conical surfaces and radial cuts.

The biconical collet represents an optimal solution for applications that require precision, repeatability and clamping speed. Its self-centering capacity and uniform pressure distribution make it irreplaceable in high-productivity contexts, such as CNC turning and precision grinding. The choice of material and surface treatment plays a crucial role in the performance and durability of the collet.

Coated in HM: It guarantees a frontal closing load approximately 50% higher than the normal bar clamping collet, however this operation is not recommended if the bar is not turned on the outside and there are geometric concentricity tolerances on the piece drawing referring to the external diameter.