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Sheet Metal Bending Guide

Bend allowance, K-factor and springback calculations

Sheet Metal Bending Fundamentals

Bend Allowance Formula

BA = (π × A / 180) × (R + K × T) where A = bend angle, R = inside radius, K = K-factor, T = thickness

K-Factor Values

Material	Thickness	K-Factor Range	Recommended
Mild Steel	0.5-3mm	0.33-0.42	0.35
Stainless Steel	0.5-3mm	0.30-0.40	0.35
Aluminum	0.5-3mm	0.40-0.45	0.42
Copper/Brass	0.5-3mm	0.35-0.42	0.38

Minimum Bend Radius

Mild Steel: 1x thickness (with grain), 0.5x (across grain)
Stainless Steel: 2x thickness minimum
Aluminum 6061: 1.5x thickness
Aluminum 5052: 0.5x thickness

Springback Compensation

Springback angle depends on material yield strength. Typical overbend angles:

Mild Steel: 1-3 degrees
High Strength Steel: 5-10 degrees
Aluminum: 2-5 degrees