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Collet Classification

The ER collet is one of the collets, a connecting tool between the shank and the CNC tool.

The ER spring collet was invented by Swiss company REGO-FIX. Nowadays it is widely used in various fields of machining and clamping.

Mainly used in drilling, milling, reaming, tapping and grinding.

Due to the 16-slot design, it allows a large clamping range and has a good radial runout error.

And divided into ER8, ER11, ER16, ER20, ER25, ER32, ER40 and ER50 specifications, it is used for all tool clamping.


According to the clamping size, it can be divided into metric and inch collets.

Metric and inch collet parameters

Metric and inch collet parameters

Metric clamping is 0.5-34MM

Inch clamping is 1/8" 1/4" 1/2", etc.

According to the accuracy, it can be divided into A grade and AA grade.

The accuracy of class A is between 0.015-0.03

AA level accuracy: between 0.005-0.02

According to the function, it can be divided into drilling type and wire attack type.

Drilling type clamping surface is round

Wire tapping clamping surface is square

According to the specifications, can be divided into ER8-11-16-20-25-32-40-50

ER8 can be clipped 0.5-5.0MM

ER11 can be clipped 1.0-7.0MM

ER16 can be clipped 1-10MM

ER20 can be clipped 1-13MM

ER25 can be clipped 1-16MM

ER32 can be clipped 1-20MM

ER40 can clip 2-26MM

ER50 can be clipped 12-34MM