SHEET METAL PRESS BRAKE & LASER CUTTING SUITE

Sheet Metal Bend Allowance & K-Factor Calculator

Compute precise Bend Allowance (BA), Outside Setback (OSSB), Bend Deduction (BD), Flat Blank unfolded dimensions, and required Press Brake Air Bending Tonnage for clean DXF unfolding and zero-scrap sheet metal fabrication.

1. Part & Material Parameters

Material Alloy & Tensile Strength

Sheet Thickness (T) [mm]

Nominal sheet metal gauge thickness.

Inside Bend Radius (R) [mm]

Typically equal to sheet thickness (1T) for standard air bending punch tools.

Bend Angle (A) [Degrees]

Angle of the finished bend (90° is standard right-angle flange).

Neutral Axis K-Factor (K)

Ratio of neutral axis shift ($t_{\text{neutral}} / T$). Typically 0.33 to 0.45.

2. Flange Dimensions & Press Tooling

Outside Flange Length 1 ($L_1$) [mm]

Outside Flange Length 2 ($L_2$) [mm]

Total Part Bend Line Width ($L_{\text{bend}}$) [mm]

Length of the sheet along the press brake bend line.

V-Die Opening Width ($V$) [mm]

Standard rule of thumb: $V \approx 8 \times T$ for mild steel, $6 \times T$ for aluminum, $10 \times T$ for stainless.

Unfolded Flat Blank Results

VALID GEOMETRY

Bend Allowance (BA)

3.77 mm

Length of arc along neutral line

Outside Setback (OSSB)

4.00 mm

Apex to tangent distance

Bend Deduction (BD)

4.23 mm

$2 \times \text{OSSB} - \text{BA}$

Total Flat Blank ($L_{\text{flat}}$)

120.77 mm

$L_1 + L_2 - \text{BD}$

Press Brake Tooling & Tonnage

Required Air Bending Force

12.5 Metric Tons

50.0 Tons / Meter

Min Flange Safe Height ($b_{\min}$)

11.2 mm

Passes $L_1, L_2 \ge b_{\min}$

Natural Air-Bend Radius ($R_{\text{air}}$)

2.56 mm

$0.16 \times V$ die width

Recommended Relief Notch

2.0 × 2.0 mm

Min $T \times T$ tear relief

DXF CAM Layer Specification

                        LAYER 0_OUTER_CUT: Continuous perimeter profile ($L_{\text{flat}} = 120.77$ mm)

                        LAYER BEND_UP_90: Tangent centerline @ 48.00 mm from Flange 1

                        RELIEF_NOTCHES: Radius/Fillet $\ge 2.0$ mm to stop corner tearing

                        KERF OFFSET: Apply laser beam kerf ($0.12 - 0.20$ mm) outward