Life is counted in cycles, not in years, and it is governed by operating stress. For wave springs the accepted method is to calculate a fatigue stress ratio from the material’s minimum tensile strength and the stresses at the two work heights. Published industry guidance maps that ratio to expected life: roughly 0.40–0.49 corresponds to 30,000–50,000 cycles, 0.61–0.67 to 100,000–200,000 cycles, and above 0.70 to more than one million. Static applications may run to 100 % of minimum tensile strength; dynamic applications should stay below 80 %. A spring designed under its endurance limit is effectively unlimited, and one designed above it will fail on schedule — which is why the required cycle count belongs on the drawing alongside the load.
Knowledge Center
Failure Analysis
Failure analysis, quality issues and prevention.
If the published answers do not match your application, send us your question and our team will review it.
Five failures recur, and two of them are geometric rather than material.
- Buckling — a helical compression spring whose free length exceeds about four times its mean diameter will bow sideways unless it is guided by a rod or a bore.
- Set and load relaxation — operating stress sitting too close to the material limit, or an alloy taken above its service temperature.
- Fatigue fracture — cyclic stress above the endurance limit, usually initiating at a surface defect.
- Space overrun — the spring turns out longer than the cavity once the rest of the design is frozen.
- Side load from unground ends — the end coil contacts on a point and tilts the load path.
A wave spring eliminates the first and the last by geometry: it is too short to buckle, and a shim end presents a flat bearing face. Set, fatigue and fit remain design decisions, controlled by operating stress and by material choice.
Yes, custom-manufactured implant-grade titanium or Elgiloy spiral rings are used in pacemaker housings and orthopedic assemblies due to their smooth, earless profile.
This rare issue is caused by extreme axial thrust forcing the turns to slide over one another due to severe groove rounding or a massive chamfer on the mating part.
When installing steel rings in an aluminum housing, specify cadmium plating, zinc-nickel plating, or use a stainless steel ring to avoid galvanic interaction.
Yes, light-duty internal spiral rings provide gentle, completely uniform 360-degree retention, keeping lenses perfectly centered without causing localized cracking pressure.
Their low profile fits into ultra-slim drill strings, and specialized alloys like Elgiloy provide survival capabilities against aggressive H2S and CO2 gases.
If the ring spins easily under normal operation, it means the ring has lost its radial tension (clinging force) due to over-expansion or thermal relaxation. Replace the ring.
Yes, their continuous grip and low mass make them highly resilient against vibration, but extremely violent systems should use heavy-duty or self-locking styles.
Primary causes include: groove walls yielding due to soft metal, excessive corner radius on the retained part pushing the ring out, or operating past the RPM limit.
Their 360-degree uniform shoulder handles massive axial loads from helical gears smoothly, saving massive weight compared to bolted end-caps.
They are used to lock bearing assemblies in place, secure internal components in hydraulic control valves, and hold turbine engine components under tight tolerances.
Measure the free height of the spring before installation and re-measure it after compression. A significant, permanent reduction indicates the spring took a set due to over-stressing.
Stainless steel and superalloy springs have an indefinite shelf life. Carbon steel springs have an indefinite structural shelf life if kept dry and properly lubricated against rust.
Ensure you are counting active waves per turn and not total waves across multiple turns. Custom designs may also alter wave counts to modify spring stiffness.
Apply an industry-approved lubricant, or specify a PTFE/dry-film coating to eliminate stick-slip friction between the spring and adjacent components.
Rough surfaces or severe manufacturing scratches act as stress concentrators, drastically reducing the fatigue life of the spring under cyclic loading.
Non-destructive testing (NDT) methods like Magnetic Particle Inspection (MPI) for carbon steel or Dye Penetrant Inspection (DPI) for stainless steel are utilized.
No, hydrogen embrittlement is primarily induced by chemical processing like acid pickling or electroplating. Raw or mechanically polished springs are not susceptible.
Uneven wear indicates that the mating components are out-of-parallel, or the spring is seated unevenly, forcing a few waves to carry the entire load.
