Sheet Metal Bend Calculator
An essential tool for sheet metal fabricators. Calculate Bend Allowance and Bend Deduction to accurately determine the required flat pattern length for precise bending operations.
The Secret to Perfect Bends
When you bend a piece of sheet metal, the material on the outside of the bend is stretched, and the material on the inside is compressed. Somewhere in between is the "neutral axis," a line that is neither stretched nor compressed. To determine the length of the flat piece of metal needed to create a bent part with the correct final dimensions, fabricators must account for this stretching and compressing. This is where Bend Allowance and Bend Deduction come in.
- Bend Allowance: The length of the neutral axis in the bend region. To find the total flat length, you add the lengths of the straight flanges to the bend allowance. `Flat Length = Flange1 + Flange2 + Bend Allowance`.
- Bend Deduction: A value that is subtracted from the sum of the flange lengths (measured to the outside apex of the bend) to get the flat length. `Flat Length = (Flange1 + Flange2) - Bend Deduction`.
What is the K-Factor?
The K-Factor is a ratio that represents the location of the neutral axis relative to the material thickness. A K-Factor of 0.5 means the neutral axis is exactly in the middle of the material, while a K-Factor of 0.33 means it's closer to the inside face. The K-Factor depends on the material type, thickness, and bending method. A common starting value for steel is 0.447.