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Press brake forming
Press brake forming bends sheet metal along a straight line by pressing a punch into a V-shaped die. In air bending, the depth of the stroke sets the angle, so one tool set makes many angles. It holds about ±1° and ±0.010–0.015 in (±0.25–0.38 mm) per bend with standard tooling, and fits one prototype to a few thousand parts.
A method under sheet metal fabrication, alongside laser cutting.
How does press brake forming work?
The schematic plays while it is on screen. Pick a phase to hold it there.
- 1
Unfold and cut the blank
The flat pattern is calculated with the bend allowance for the material and tooling, then laser cut or punched.
- 2
Set the backgauge
CNC backgauge fingers position the blank so the bend line sits exactly over the die.
- 3
Punch contacts the sheet
The ram lowers the punch to the sheet, which rests on the two shoulders of the V-die.
- 4
Air bend past the angle
The punch pushes the sheet into the V. Stroke depth controls the angle, and the brake over-bends to allow for springback.
- 5
Release and check
The ram lifts, the sheet springs back to angle, and the operator or an in-line sensor checks the angle before the next bend.
- 6
Sequence the bends
Each part follows a bend sequence planned so earlier flanges clear the punch and the machine frame.
What can press brake forming hold?
Typical ranges across principals. Your drawing, material and quantity set the real numbers in the quote.
| Angle tolerance | ±1° typical; ±0.5° with angle measurement |
|---|---|
| Bend-to-bend tolerance | ±0.010–0.015 in (±0.25–0.38 mm) per bend |
| V-die opening | 6–8× material thickness for air bending |
| Inside radius, air bend | About 0.16× V-die opening in mild steel |
| Minimum flange | About 4× material thickness |
| Springback | 1–2° mild steel; 2–4° stainless; more in high-strength steel |
| Bed length | 4–14 ft (1.2–4.3 m) typical |
| Lead time | 1–3 weeks with cutting |
When is press brake forming the right call?
Best for
- Brackets, enclosures, chassis, panels and channels
- 1–10,000 parts with standard tooling
- Blanks from laser cutting or turret punching
- Parts up to 10–14 ft (3–4 m) long on large brakes
Pick something else when
- High-volume small brackets: a progressive die forms them every stroke
- Small clips with bends in several directions: fourslide forming
- Tight angle tolerances under ±0.5° on every bend without bottoming or coining
How does press brake forming compare with the alternatives?
Typical values. Pick an alternative to see where each one wins.
Press brake forming compared with
Press brake formingProgressive die stamping
- Precisionlooser → tighter
- Volume it pays atone-offs → millions
- Upfront toolingnone → heavy
- Shape freedomnarrow → wide
Press brake forming · pick it when
Straight-line bends in cut blanks, from one prototype to a few thousand parts.
Progressive die stamping · pick it when
Flat and formed parts at high annual volume, where a part every stroke pays back the die.
About progressive die stampingMethodTypical toleranceEconomic volumeToolingLead time
- Press brake formingthis pageTypical tolerance±1° angle; ±0.010–0.015 in (±0.25–0.38 mm) per bendEconomic volume1–10,000 partsToolingStandard punches and dies; specials $1,000–$10,000Lead time1–3 weeks
- Typical tolerance±0.001–0.005 in (±0.025–0.13 mm) pierced; ±0.005–0.010 in across formsEconomic volume25,000 parts a year and upTooling$20,000–$150,000+Lead time8–16 weeks for the die
- Typical tolerance±0.005–0.015 in (±0.13–0.38 mm) on formed featuresEconomic volume10,000 parts and upTooling$5,000–$25,000Lead time4–8 weeks
Which design rules keep press brake affordable?
Rules of thumb principals apply at DFM review. Each one has a reason.
RuleTargetWhy
- Minimum flange length
- ≥ 4× thickness
- The flange must span half the V-die opening plus a margin, or it falls into the die.
- Inside bend radius
- ≥ 1× thickness
- Tighter radii crack harder alloys and need special tooling. 5052 bends well; 6061-T6 cracks at tight radii.
- Hole to bend distance
- ≥ 2.5× thickness + radius
- Holes closer than this stretch into ovals.
- Bend relief
- Width ≥ thickness; depth ≥ radius + thickness
- Relief cuts stop tearing where a bend meets an edge.
- Same radius everywhere
- One radius per part
- Each radius may need a tool change. One radius means one setup.
- Dimension the right side
- To the inside or outside, consistently
- Mixed references stack bend tolerances unpredictably.
What drives the cost of press brake?
In order of impact.
- 1
Number of bends
Each bend is a handling cycle. A 6-bend part costs roughly twice as much brake time as a 3-bend part.
- 2
Setups and tool changes
Different radii, flange heights or special tools add setup time, spread over the order.
- 3
Part size and weight
Large blanks need two operators or a follow-support.
- 4
Tolerances
Angle checks between bends, or bottoming for tighter angles, slow the cycle.
- 5
Blank cost
Laser cutting or punching the blank is often half the part's cost.
Budgetary estimate for a formed L-bracket, from the same estimator as the part builder. Change a size, the quantity or the material and the price updates.
Bracket · Sheet metal
Order total $488
- Tooling
- None
- no hard tooling
- Piece price
- $3.68
- before setup + tooling
- Lead time
- 5–12 days
- to first production
Size
Drag a row to adjust · click to type
Width60.060.0 mm
Leg A (vertical)50.050.0 mm
Thickness2.002.00 mm
Quantity
Price per part falls as volume rises
Exact quantity100100 pcs
Material
Design checks pass
Open in builderBudgetary estimate for a representative part. Firm quotes come from principals after drawing review.
Press brake questions
How much tonnage does a bend need?
For air bending mild steel, a common estimate is tons per foot ≈ 575 × T² ÷ V, with thickness T and V-die opening V in inches. A 0.125 in (3.2 mm) sheet in a 1 in (25 mm) V needs about 9 tons per foot. Stainless needs about 1.5 times that.
What is springback?
The elastic recovery of the sheet after the punch lifts. Mild steel opens up 1–2°, stainless 2–4°, and high-strength steels more. The brake over-bends to compensate.
What is the difference between air bending, bottoming and coining?
Air bending touches the sheet at three points and sets the angle by stroke depth. Bottoming presses the sheet against the die walls for more consistent angles. Coining presses harder still to set the radius. Air bending needs the least force and is most common.
Why does my flange length have a minimum?
The sheet has to span the V-die opening, typically 6–8 times its thickness. A flange shorter than about half the opening slips into the die. Rule of thumb: at least 4 times thickness.
When should a formed bracket move to stamping?
When volume reaches tens of thousands a year. A progressive die cuts and forms every stroke, while a press brake handles each bend separately. Short-run stamping sits in between.
Quote press brake forming with a rep.
Send a STEP file and drawing. A rep routes the RFQ to principals that run this method every day, and brings back firm quotes.