At first glance, a Nikken Slim Chuck and a standard ER Collet Holder look almost identical, both having the same 7/24 spindle taper.

However, all Nikken Tooling has a precision finish ground taper in comparison to most standard ER tool holders, which only have a turned finish. To the naked eye, these may look very similar but the rigidity and performance when machining are completely different. This difference in manufacture can lead to a variety of issues such as vibration, reduced cutting tool life, poor surface finish and increased spindle fretting and wear.

Nikken SK collets have an 8 degree taper compared to an ER collet taper of 16 degrees. Although this may seem to be just a change of design, it actually provides superior performance! The 8 degree design of the Nikken SK collet delivers a higher run-out accuracy of either 5 microns, (with a standard SK collet) at 4 x diameter of the cutting tool, or 3 microns, (with an SK-P) at 4 x diameter of the cutting tool. This, combined with the TiN Bearing nut, also provides a higher gripping torque on the shank of the cutting tool which can be up to 4 times greater.

There are many different collet choices available which are application specific. For example, an SK-A type collet is specifically for end-milling applications as the collet has no collapse which provides a size for size accurate fit with a high precision run-out tolerance of 3 microns at 4 x diameter of the cutting tool. Many ER collet holders and collets cannot guarantee any run-out tolerance which is detrimental to surface finish and tool life.

Most ER collets are collapsible by up to 1mm. Nikken SK collets are only collapsible by up to 0.5mm which provides greater gripping force and stability as the collet is not compressed as much, which will ultimately deliver a more durable and better long-term performing product.

FACT: When tool run-out of 21 microns is reduced to 3 microns, the tool life at the actual cutting edge will improve by approximately 5 times!