ER Collet Chucks (ER11 to ER40): Runout, Clamping & Torque Specs
ER collets (DIN 6499) are the most universal flexible tool clamping system in CNC manufacturing, featuring an 8° double-angle taper and 1mm collapse range for drills, taps, reamers, and end mills.
Engineering Specifications & Parameters
Taper Angle
8 Degree Double-Angle Taper
Clamping Range
1.0 mm collapse range per collet
Standard Grade TIR
< 0.015 mm (0.0006 in)
Standard Specification
DIN 6499 / ISO 15488
Ultra-Precision (UP) TIR
< 0.005 mm (0.0002 in)
ER Collet System Engineering
ER (Rego-Fix) collets utilize a double-angle 8-degree taper with 16 continuous axial slits, providing uniform 360-degree concentric compression across a 1.0 mm clamping range.
ER Size Series & Capacity Chart
ER11: Clamping 0.5 – 7.0 mm (Torque: 25 Nm)
ER16: Clamping 0.5 – 10.0 mm (Torque: 55 Nm)
ER20: Clamping 1.0 – 13.0 mm (Torque: 80 Nm)
ER25: Clamping 1.0 – 16.0 mm (Torque: 100 Nm)
ER32: Clamping 2.0 – 20.0 mm (Torque: 140 Nm)
ER40: Clamping 3.0 – 26.0 mm (Torque: 180 Nm)
Critical Collet Assembly Protocol
Never insert the tool shank into the collet first! The collet must always be snapped diagonally into the clamping nut eccentric extractor ring before threading onto the chuck body.
Frequently Asked Questions
Why must the ER collet be snapped into the nut before inserting the tool?
The nut contains an eccentric extractor ring that locks into the collet groove; failing to snap it in prevents proper seating and destroys the collet when tightened.
What happens if an ER collet nut is over-torqued beyond specification?
Excessive torque plastically deforms the collet taper, inducing severe runout and permanently ruining the concentricity of the chuck.
