Product Overview
A collet is a segmented spring-steel sleeve that grips cylindrical tools or workpieces with high precision when compressed inside a tapered seat. Collets serve as the critical interface between machine spindle and cutting tool in milling, drilling, and turning. The ER collet system has become the global standard for CNC tool holding due to its wide clamping range and excellent concentricity.
Types and Features
ER spring collets feature a sixteen-degree taper with longitudinal slots allowing uniform radial contraction when the nut tightens. Sizes range from ER8 to ER50, covering tool diameters from half a millimeter to thirty-four millimeters. Each size provides a one-millimeter collapse range per collet. Precision grades achieve runout below five microns for high-speed machining. TG collets offer higher clamping force through steeper taper design for heavy milling cuts. Sealed coolant collets channel fluid through the tool body for improved chip evacuation.
How to Choose
Select collets based on the tool shank diameters most common in your operations, purchasing sets covering your full range of end mills and drills. Finishing operations require premium-grade collets rated for five-micron runout or better. Standard-grade collets with eight-micron specifications suit roughing work at lower cost. Always verify the collet collapse range before purchasing to ensure proper gripping.
Replacement and Installation
Install the collet into the clamping nut first, ensuring the keyway engages with the eccentric ring. Thread the nut onto the chuck body by hand, insert the clean tool shank, then tighten to specified torque. Never overtighten, as excessive force distorts the collet and increases runout rather than improving grip.
Maintenance Tips
Clean collet bores and taper surfaces after every tool change to remove metal particles that affect seating precision. Inspect periodically for cracks, deformation, or worn slot edges indicating fatigue. Store in dedicated cases with individual compartments to prevent surface damage and corrosion during extended storage.
