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Calcimator

K-Factor Calculator

Determine K-factor from material type, thickness, bend radius ratio, and bending method for accurate flat patterns.

Inputs

mm
mm

Results

K-Factor

0.34

R/t Ratio1.33
Neutral Axis Offset0.5 mm
Neutral Axis Radius2.5 mm
Bend Allowance at 90°3.93 mm
Min Bend Radius0.75 mm
How to Use This Calculator
  1. Select your material type (soft aluminum, copper, mild steel, stainless, or hard brass) from the preset list.
  2. Enter material thickness and inside bend radius.
  3. Review the recommended K-factor and its effect on neutral axis position.
  4. Verify the K-factor with a test bend: measure actual developed length and back-calculate K.
  5. Use a lower K-factor for harder materials and tighter radii -- the neutral axis moves inward under compression.

How the result changes with Inside Bend Radius

Inside Bend RadiusK-Factor
100.43
350.5
650.5
900.5

What each input means

Material Thickness
Sheet metal thickness.
Inside Bend Radius
Inside radius of the bend.
Material
Material hardness affects neutral axis position.
Bending Method
Bending method affects how material flows during forming.

What each result means

K-Factor
Ratio of neutral axis offset to material thickness (0 to 0.5).
R/t Ratio
Bend radius to thickness ratio.
Min Bend Radius
Minimum recommended radius to avoid cracking.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Material Thickness = 1.5, Inside Bend Radius = 2, Material = 2, Bending Method = 1 = 4 input(s) provided
  2. Calculate K-Factor
    K-Factor
    0.336 = 0.336
  3. Calculate R/t Ratio
    R/t Ratio
    1.33 = 1.33
  4. Calculate Neutral Axis Offset
    Neutral Axis Offset
    0.504 = 0.504

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