ER Collets Guide: How to Choose and Take Care of Them

ER collets are one of the most common ways to hold a cutting tool on a milling or drilling machine. They grip the tool all around its shank, which gives a firm and even hold. Here is a short guide to choosing and caring for them.

What are ER collets?

ER collets follow the DIN 6499 standard. They come in sizes from ER8 to ER50. The number shows the size of the collet and the range of tools it can hold. Bigger numbers hold larger tools.

How to choose the right collet

• Pick the right series. Make sure the collet fits your collet nut and holder.
• Match the shank size. Each collet holds a small size range, so choose the one closest to your tool shank.
• Buy a set. A set covers many tool sizes and is more useful in a busy shop.

What about expansion collets?

Expansion collets are used to hold tubes and pipes from the inside. They are helpful for centre to centre machining on long tubes. They can also be made as per your drawing.

How to take care of your collets

• Keep the collet, nut and holder clean. Dust and chips cause poor grip.
• Do not tighten the nut without a tool inside the collet.
• Do not use a collet for a shank that is too small for it.
• Check for wear or cracks, and replace damaged collets.
• Store them in a case so they stay clean and safe.

Good care means better grip, better accuracy and a longer life for your tools. See our collets to find the right one.