Springing a solution
November 1st 2007

Use of standard duty coiled pins as hinge pins in a circular saw blade guard application was causing problems during manufacture due to excessively high insertion forces. Following design advice from Spirol Industries, coiled spring pins are now used that have just half the exertion force.

Different assembly lines were being used to install the coiled pin and all the insertion problems were being experienced on the automated line that had less than half of the insertion force of the semiautomated line. Based on empirically derived insertion data for the coiled pin, the automated line had a cylinder that was undersized for this application.

When Spirol was asked for help, no shear strength requirements for the coiled pin were supplied. A simple option, which would require no changes to automation equipment or hole sizes in components, was to change to a light duty coiled spring pin. The insertion force for the same coiled pin in light duty was about half that of the standard duty pin in the same application.

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