Wave Spring Design Theory

There are 4 critical factors when considering a wave spring –

  1. Constraints of the application: Bore/shaft, ID/OD etc.
  2. Load
  3. Working height at which the load is applied
  4. Material desired

Wave Spring Design General Considerations

  • If a spring is designed for static application, make sure that the % stress at working height is less than 100%. Spring will take a set if subjected to a higher stress.
  • If a spring is designed for dynamic application, make sure that the % stress at working height is less than 80%. Spring will take a set if subjected to a higher stress.
  • Few things to remember:
    • If the work height per turn is less than (2 * Wire Thickness), the spring will operate in a 'non-linear' range and actual loads may be higher than calculated
    • Number of turns must be between 2 and 20
    • Number of waves per turn (N) must be in ½ increments
    • Min. Radial wall = (3 * Wire Thickness)
    •  Max. Radial Wall = (10 * Wire Thickness)
    • It is NOT recommended to compress a wave spring to solid

OD expansion and OD tolerance must be taken into account while designing a spring to fit in a bore and/or over a shaft

Wave Spring Nomenclature:

Formulas:

Operating Stress,

Design stresses for wave springs:

Static/Low Cycles

 

 

No preset

:

100% of tensile strength

Preset springs

:

150% of tensile strength

Dynamic Service

 

 

104 cycle life

:

80% of tensile strength

105 cycle life

:

53% of tensile strength

106 cycle life

:

50% of tensile strength

107 cycle life

:

48% of tensile strength



Fatigue Stress Ratio,

Where:
s = Material tensile strength
S1 = Calculated operating stress at lower working height (must be less than s)
S2 = Calculated operating stress at upper working height

X

 

Estimated Cycle Life

< .40

:

Under 30,000

.40 - .49

:

30,000 – 50,000

.50 - .55

:

50,000 – 75,000

.56 - .60

:

75,000 – 100,000

.61 - .67

:

100,000 – 200,000

.68 - .70

:

200,000 – 1,000,000

> .70

:

Over 1,000,000



Deflection,                   Spring Rate,

Multiple Wave Factor (K):

N

2.0-4.0

4.5-6.5

7.0-9.5

10.0 & Over

K

3.88

2.9

2.3

2.13

OD Expansion = (0.02222 Rw N T) + b

Where:



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