Home » Tools » Form spring bending force calculator Tools Bending Force Calculator for Form Springs | Alfred Kron GmbH Determine the maximum spring force up to plastic deformation, the corresponding deflection and the feasibility of your inner bend radius – for spring steel strip 1.4310, 1.4301, C75S and CuSn6. Input Spring Geometry & Material What would you like to calculate? Limit Force max. force before yielding Force at Deflection F = k · x (Hooke) Load Direction relative to the bend With Bend Direction F closes the bend Against Bend Direction F opens the bend The spring force stays the same – the straight spring arm is symmetrical. Direction affects only the stress state in the bend zone. Material Spring steel strip Temper / Strength affects Rp0.2 Strip thickness t0.2–1.0 typ. mm Strip width b mm Spring length Lfree mm Radius Riinner mm Target deflection x at the free spring end mm Safety factor S 1.0 · σzul = Rp0,2 / S 1.0 · yield limit 1.5 · fatigue 2.0 · conservative Model: Cantilever leaf spring (fixed at one end), point load at the free end. I = b·t³/12 · W = b·t²/6 k = 3·E·I/L³ · F = k·x (Hooke) Fzul = W·σzul/L · σzul = Rp0,2/S The limit force Flim depends on Rp0.2, not on Young's modulus. E alone determines the deflection at which that force is reached. Diagram Schematic R i M Tension side (outer) closes t F f L Maximum Spring Force Before Yielding —N Force at the free spring end at which the outer fibre reaches Rp0.2 Yield Limit Utilisation — — Result Calculated Values Deflection f at Flim —mm Spring rate k —N/mm Section modulus W —mm³ Allow. bending stress σallow —MPa Check Inner Bend Radius Ri Evaluates the ratio Ri/t = — against the material-specific minimum (Ri/t)min = —. Too small a radius causes notch effects and cracking on the outside of the bend. 0criticalmarginalsafe4·(R/t)min — — Reference Material Properties Material Mat.-No. Rm (MPa) Rp0.2 (MPa) E (MPa) (Ri/t)min Note on material values: The stored Rp0.2 values are conservative design values at the lower end of the standard scatter band. The temper designation (+C1300, R620, F90 …) states the minimum tensile strength Rm, not the yield strength – Rp0.2 is typically 70–85 % of it, depending on work hardening. Real batches usually exceed these values; your mill certificate always governs. On the model: Linear beam bending theory for a cantilever rectangular spring with a point load at the free end, valid for small deflections (f ≲ L/5). A design guideline – it does not replace FEA or sample testing. For fatigue life, curved geometries or large deflections, please contact us – we review your spring free of charge. Print result Copy values Reset Direktkontakt Zeichnung vorhanden? Jetzt kostenloses Angebot anfragen. Unser Vertriebsteam berät Sie zu Material, Toleranz und Wirtschaftlichkeit – schnell, kompetent und unverbindlich. sales@kron-solingen.de +49 212 26225-22 Mo–Do 07:30–16:00 Uhr · Fr 07:30–15:00 Uhr Other interesting articles: Bending Force Calculator for Form Springs | Alfred Kron GmbH Material Advisor – Stamped & Stamped-Bent Parts | Alfred Kron GmbH