Music wire springs used in a printer return mechanism failed near the bend in the hook portion of the spring during qualification testing. Samples were examined in a scanning electron microscope equipped with an energy-dispersive x-ray microprobe. Fatigue fractures originated at rub marks on the inside edge of the spring. An investigation of loads encountered in service indicated that the springs had been loaded to a large fraction of the yield strength. Redesign of the spring mechanism was recommended.
Michael Neff, Analysis of Music Wire Springs Used in a Printer Mechanism, Handbook of Case Histories in Failure Analysis, Vol 2, Edited By Khlefa A. Esaklul, ASM International, 1993, p 451–454, https://doi.org/10.31399/asm.fach.v02.c9001267
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