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Compression Springs
Compression Springs
Extension Springs
Extension Springs
Torsion Springs
Torsion Springs

MSDivisions
14 Montgomery Street
Middletown, NY 10940

1-800-633-7734
845-343-9078

fax: 845-344-2175
To search for or design a particular type of spring click on the picture above. 8/21/2017, 10:11:18 PM CST


Technical failure analysis
We strongly recommend that people new to this field review at leat one of the three links below.
They provide valuable backgound information and concepts that will enhance your abilities.

1)Written about bone fracures; but the same principles apply. (no math)
2) Describes tensile tests and the concepts that affect failures.
3)Wikipedia's description of the same concepts.


CONDITION ANALYSIS POSSIBLE SOLUTIONS
Failure on first three coils Usually due to rapid or impact forces that deflect these coils more than others. Failure on the 3rd coil may indicate "coil clashing" on load application possibly due to harmonics/vibration effects. Redesign for natural frequency > 13 times operating frequency. Vary pitch or use conical springs to change natural frequency as load is applied. Use multiple springs. Check natural frequenies for both unloaded and preloaded conditions as appropriate.
Failure partially discolored/dirty Failure is probably due to crack propogation over time - A fatigue failure. Failure may have initiated at a small inclusion and may not be indicative of general conditions. Spring may not have received sufficient stress relief after forming. Re-design to reduce stresses if no inclusions found. Switch to higher strength carbon steels or "valve quality" carbon steels. Extend stress relief time, shot peen springs, or reduce stress levels be redesigning.
"Necking" - thinner cross section in area of failure Spring probably failed in tension. It first yielded, then broke. Excessive loads are most likely the cause. Same as above.
Sudden cracking associated with premature failure. Sometimes without any loads. Brittle failure. Often on plated springs as a result of hydrogen embrittlement (failure to bake springs properly and immediately after electroplating). Also possible on some materials (such as chrome silicon/chrome vanadium) if not heat treated promptly after forming. Also possible that the material may not have been properly tempered, leaving it too hard to act as a spring. Correct baking at plating. Use mechanical plating to avoid hydrogen embrittlement. Use stainles steel instead of plated parts. Use epoxy coatings or oxide coatings, or phosphate coatings, or paint finishes instead of electrooplating.

Additionnal Links

oscillation: natural and harmonic frequencies
Wikipedia - Basics of oscillation.
Wikipedia - Fundamental Frequency.
Wikipedia - Harmonics.

Torsion Failure
from Yahoo, pictures of torsion failures. Note: compression and extension springs are subject to torsional stresses.



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