The problem of end coil fatigue failure was discussed in the last Cautionary Tale, but before fatigue occurs there is wear, if the failure occurs at the position where the end tip touches the first active coil. Wear will also occur whenever a spring is in moving contact with an adjacent component, such as in buckling compression springs that contact their guide rod (or tube) and in torsion springs that operate on a mandrel. Wear of a spring in service is unlikely to lead directly to a risk of failure, but it will affect the load/deflection characteristic. When it becomes severe, it may set up abnormal stresses that lead to fatigue crack initiation.
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