The K-factor for this configuration is 0.432. Consider a bend radius of 10 mm when you bend a 10 mm thick sheet to a 60° bend. Mathematically,
K = (180×BA) / (π×θ×T) − (Rᵢ/T)
K = (180×15) / (π×60×10) − (10/10)
K = 0.432
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