HELICAL SPRINGS
FOLLOWING DIN EN 13906-1,2,3
Order : Dware
Project : HeliSpring
Subproject : Dimensioning compression spring
Project item : Metallfedern
Spring ID : S.198
Calculated by : André Dewispelaere
Organization : Dware
Date : 26/07/2021 




   Spring wire grade




 Nr, Cl, Spring Wire Grade       ,      E,     G,  rho,  Rm1, Rco




125, DM, EN 10270-1 DM           , 206000, 81500, 7.85, 1980, 740
Calculated wire properties Symbol Unit Value
Wire diameter d mm 5.000
Minimum value tensile strength Rm N/mm˛ 1460
Modulus of rigidity G N/mm˛ 81500
Modulus of Elasticity E N/mm˛ 206000

Design Specifications Symbol Unit Value
Minor axial spring force F1 N 280.0
Axial stroke sh mm 21.0
Major axial spring force F2 N 620.0
Design stroke stress τh N/mm˛ --
Design major stress τ2 N/mm˛ --
Influence factor spring seat ν -- 0.5
Number of loading cycles Ncy Mcy 10.000
Type of spring end A ETA -- D squar+grnd
Extra inactive conjoint coils nnaA -- 0.00
Type spring end B ETB -- D squar+grnd
Extra inactive conjoint coils nnaB -- 0.00
Outside diameter not greater than De mm 40.0
Target coil ratio w -- 0.00
Coiling -- -- cold
Shot peening -- -- No
Hand of coiling -- -- right
Geometry calculation Symbol Unit Value
Calculated wire diameter dc mm 4.80
Selected wire diameter d mm 5.000
Diameter deviation Ad mm 0.025
Mean diameter of coil D mm 35.00
Spring index w -- 7.00
Outside diameter of spring De mm 40.0
Inside diameter of spring Di mm 30.0
Required spring rate Rr N/mm 16.190
Number of active coils n -- 9.50
Spring rate R N/mm 15.632
Sum of smallest coil spaces Sa N m 12.3
Total number of coils nt -- 11.5
Compressed length to solid state Lc mm 57.8
Minimum permissible spring length Ln mm 70.1
Nominal free length of spring L0 mm 118.6
Coil pitch at free length m0 mm 10.900
Coil space at free length a0 mm 5.900
Calculation spring diagram Symbol Unit Value
Minor axial deflection s1 mm 17.9
Length at minor axial deflection L1 mm 100.7
Minor axial spring force F1 N 280.0
Major axial deflection s2 mm 38.9
Length at major axial deflection L2 mm 79.7
Calculated major axial load force F2 N 608
Maximum permissible deflection sn mm 48.6
Minimum permissible spring length Ln mm 70.1
Maximum permissible spring force Fn N 760.1
Axial deflection to solid state sc mm 60.8
Compressed length to solid state Lc mm 57.8
Spring force at solid state Fcth N 950.0
Strength calculation Symbol Unit Value
Stress correction factor k -- 1.200
Corrected minor torsional stress τk1 N/mm˛ 240
Corrected major torsional stress τk2 N/mm˛ 520
Permissible static torsion stress τP N/mm˛ 730
Safety factor major torsion stress SF -- 1.40
Torsion stress max permiss deflect τn N/mm˛ 542
Permissible static torsion stress τP N/mm˛ 730
Safety fact max permiss deflection SFn -- 1.35
Stress at solid state τc N/mm˛ 677
Permissible stress at solid state τcP N/mm˛ 820
Safety factor stress at solid stat SFc -- 1.21
Strength domain -- -- endurance
Permissible endurance stress τeN N/mm˛ 328
Permissible upper torsion stress τkO N/mm˛ 537
Safety factor upper torsion stress SFO -- 1.03
Lower torsional stress τkU N/mm˛ 240
Corrected stroke torsional stress τkh N/mm˛ 281
Permissible stroke stress τkH N/mm˛ 298
Safety factor on stroke stress SFH -- 1.06
Weight calculation Symbol Unit Value
Length of wire for spring lw mm 1270
Mass of spring mw g 196
Calculation buckling diagram Symbol Unit Value
Influence factor spring seat ν -- 0.5
Slenderness grade νL0/D -- 1.694
Major deflection/length ratio s2/L0 -- 0.328
Buckling at deflection of sK mm 0.0
Safety factor on buckling SK -- 0.00
Is spring buckling safe -- -- Yes