What establishes a useful blank
- Bend allowance is measured along the neutral axis.
- A sequential profile with N bends has N + 1 primary flanges.
- Bend direction and radius change the folded geometry and developed length.
Sheet Metal Engineering
Move logically from material and bend data to bend allowance, developed blanks and preliminary press-brake capacity.
SHEET-METAL WORKFLOW
Geometry first, manufacturing judgement throughout.
Sheet-metal development converts a folded design into a flat blank. Neutral-axis location, bend radius, tooling, grain direction and material condition mean that production test data must control final blanks.
KEY CONCEPTS
Inputs that must match the process
- K-factor
- Bend allowance
- Flat pattern
Typical applications: Enclosures · Brackets · Ducts and formed panels
ENGINEERING PRINCIPLE
Bend allowance
BA = θ(R + Kt)
- θ — bend angle, radians
- R — inside radius, mm
- K — K-factor
- t — thickness, mm
Use a K-factor established for the actual material, tooling and bend method.
WORKED EXAMPLE
One 90° bend with stated inputs
- Known values
- θ = 90°; R = 3 mm; t = 2 mm; K = 0.33
- Substitution
- Convert θ to π/2 rad and substitute
- Interpretation
- The allowance for that bend is about 5.75 mm before trial-bend validation.
AVAILABLE CALCULATORS
Validated sheet-metal calculations
REVIEW BOUNDARIES
Check before releasing a blank or selecting a press
Material conditionConfirm material grade, thickness, temper, coating and grain direction from the controlled specification.Tooling and processVerify punch radius, V-opening, bend method, springback allowance and shop-specific K-factor with a trial bend.Machine capacityUse tonnage results only as a preliminary estimate; check tool loading, machine limits, setup and safety procedures.ReferenceJ. G. Bralla, Handbook of Manufacturing Processes; approved shop bend-test data remains controlling.