by Christie L. Jones, Market Development Manager, Spirol International Corporation

When installing Coiled Spring Pins, it is important that the installation tool, often called a “quill”, is large enough to cover the entire end of the Coiled Pin. The quill should be sized such that it pushes on all five coils simultaneously throughout the entire installation process. Otherwise, the pin will be difficult – if not impossible – to properly install into the assembly.

If the quill is too small, the inner coils will push through the centre of the pin creating a “telescoping” effect and push out the back end of the Coiled Pin. Sometimes, users refer to this as the pin “unwrapping”. It is important to note that it is impossible for pins to “telescope” or “unwrap” if the proper insertion quill is used. A by product of pushing on the inner coils is elevated insertion forces, and if the quill is too small, the Coiled Pin will not be able to flex to take on the diameter of the hole since the quill will be lodged in the ID of the pin.

Occasionally, a company will develop an insertion quill that has a stepped end that is intended to fit into the ID of the Coiled Pin to “help align the pin with the hole”. There are two problems with this scenario. The first problem is that the actual centre of the Coiled Pin is not in the centre of the ID.

Therefore, the effect of sticking something into the ID of the pin is that it will actually knock the pin off-centre from the hole! The second problem is that the nib at the end of the installation tool may prevent the pin from collapsing as it is inserted into the hole.

This can significantly raise insertion forces; and if the nib is large enough, prevent full insertion of the pin into the hole. In some cases, the quill can break off and get stuck in the ID of the pin causing downtime on the assembly line.

Another common issue is when a company continues to use a worn insertion quill. Over time, the end of the insertion quill will break down.  At some point, the end of the quill will be too small such that it will not cover the entire end of the Coiled Pin. As described above, the quill will press on the inner coils of the pin, and insertion issues will arise.

For more information, visit or contact Spirol Industries Ltd, Princewood Road, Corby, Northants, NN17 4ET, Tel: +44 (0) 1536 444800, Fax: +44 (0) 1536 203415, email: