Compression Coil Spring Design

P       = axial load, N

Do = outer diameter of coil, mm

Di = inner diameter of coil, mm

d        = diameter of wire, mm

          = (Do Di) / 2

D       = mean diameter of coil, mm

          = (Do + Di) / 2 = (Do - d) = (Di + d)

p        = pitch of coils, mm

δ        = deflection of spring, mm

n        = number of active coils

C       = spring index = D/d

            = (4 : 12);

              less than 4; it is difficult to manufacture,

              more than 12; it is likely to buckle.

G       = shear modulus of elasticity, N/mm2

Kw = Wahl factor

τs       = direct shear stress, N/mm2

τmax   = total shear stress, N/mm2

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Where:

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* Every care has been taken to ensure the accuracy of this calculators but no liability can be accepted for any loss or damage whether direct, indirect or consequential arising out of the use of the calculators.