Live Knowledgebase > Spindle motors and tooling > Collets > What is the difference between ER & OZ

Please Wait a Moment

Yeti Tool Ltd | Knowledge Base

Search for Answers in our Knowledge Base

Our knowledge base is under maintenance

There may be articles with content missing, if you are after this information please submit a support ticket here.

What is the difference between ER & OZ

Understanding the difference between ER & OZ collets.

< Previous | List | Next >


We offer spindles to cater for 2 different types of collet.

  • OZ series (ISO 10897)

  • ER series (ISO 15488)

Which is best for you

The OZ series is the cheaper solution, but the ER collet offers benefits which include:

  • Improve tool changing

  • Better part finish

  • Improved holding reliability 

  • and the ability to cater for a wide tool shank range (read on to find out more).

If you already have some collets in your tools, this may also be a deciding factor.

Different collets for different spindles


Collet type

Part Number

Yeti Tool SC0 110V



Yeti Tool SC1 110V



Yeti Tool SC1 230V



AMB 110V



AMB 230V



AMB Precision 230V



What makes the ER collet different?

Both collets have slots in them to allow the collet to compress when the nut is tightened, gripping the shank of the tool.

However, the positions of the slots vary. Note how the OZ slots only come from one end - they all start from the top (A) - whereas the ER slots start at both top (B) and bottom (C).

The OZ slots only extend from the top, so when the OZ collet is compressed, the collet only folds inward only at the bottom. This makes the clamp force uneven along the length of the tool, weakest at the back (X). This is tangential clamping.


The ER slots extend from both the top and the bottom, so when the ER collet nut is tightened, the collet compresses evenly along the length of the tool shank. We call this even clamping.

Tangential clamping (OZ) does not perform as well as even clamping (ER) in various different areas of operation.

Advantages of the ER series

  • ER is less prone to jamming during tool change.

    • The fact that the ER collet can compress at both ends means it is easy to free from the spindle core.

  • ER reduces wear, vibration and noise during operation.

    • This is because even clamping reduces run-out on the tool.

  • ER has an improved clamping force on the tool.

    • An even clamp on the tool means that less torque is needed on the nut to hold the tool. Ultimately this reduces the risk of tools pulling out in the middle of a job.

  • ER collet allows for a total clamping range.

    • Because the collet can compress evenly, it can hold tools up to a millimeter below the shank diameter. The OZ collet can only be used for the nominal diameter.

< Previous | List | Next >

If this article didn't solve your problem, please submit a support ticket here


Rami is the author of this solution

Glad we could be helpful. Thanks for the feedback.

Sorry we couldn't be helpful. Your feedback will help us improve this article.

Did you find it helpful?

Yes   No
Updated on Fri, 09 Jul 2021