Bending Application Library
Twelve real part types, worked backwards to the setup that forms them — material, V-opening, force estimate and the machine class that handles the job.
Buyers rarely ask for a machine. They ask for a part: a door that closes flush, a duct that seals, a bracket that lands on a bolt hole the first time. This library works backwards from the part to the setup — material, thickness, V-opening, tonnage estimate and the machine class that handles it.
Every tonnage figure below is an order-of-magnitude estimate for air bending, calculated from the standard shop formula:
Force (kN) ≈ 650 × t² × L ÷ V
t = sheet thickness in mm · L = bend length in metres · V = die opening in mm. Multiply by ~1.5 for stainless, ~1.4 for high-tensile plate, ~0.6 for aluminium. Add 20–30% headroom over the estimate and never specify a machine that runs at 100% of rated force every cycle.
Representative parts
| Part | Material | t | Bend length | V-die | Est. force | Machine class |
|---|---|---|---|---|---|---|
| Enclosure door | Cold-rolled steel | 1.5 mm | 1.2 m | 12 mm | ~15 t | 40–63 t / 1600–2500 mm |
| Control cabinet back plate | Cold-rolled steel | 2 mm | 2.0 m | 16 mm | ~33 t | 80–110 t / 2500–3200 mm |
| HVAC duct fitting | Galvanised steel | 0.8 mm | 2.5 m | 8 mm | ~13 t | 40–63 t / 2500 mm |
| Kitchen counter front | 304 stainless | 1.2 mm | 2.0 m | 10 mm | ~28 t | 63–80 t / 2500 mm |
| Signage channel letter return | Aluminium 5052 | 1.5 mm | 0.3 m | 12 mm | ~2 t | 30–40 t / 1600 mm |
| Equipment mounting bracket | Cold-rolled steel | 4 mm | 0.3 m | 32 mm | ~10 t | 40–63 t / 1600 mm |
| Steel-structure gusset | Q355 / S355 | 10 mm | 0.4 m | 80 mm | ~49 t | 100–160 t / 3200 mm |
| Truck chassis bracket | Q355 / S355 | 8 mm | 1.0 m | 63 mm | ~99 t | 160–200 t / 3200 mm |
| Elevator landing sill | Stainless 304 | 3 mm | 1.5 m | 24 mm | ~55 t | 110–160 t / 3200 mm |
| Solar mounting rail | Aluminium 6063 | 2.5 mm | 2.0 m | 20 mm | ~24 t | 63–80 t / 2500 mm |
| Agricultural hopper side | Cold-rolled steel | 3 mm | 3.0 m | 24 mm | ~73 t | 110–160 t / 3200–4000 mm |
| Ship / tank shell course | Q235 | 12 mm | 3.0 m | 100 mm | ~280 t | 400 t / 4000 mm and up |
Read the estimate as a floor, not a spec. Real force depends on actual tensile strength (which varies more between steel batches than most datasheets admit), bend radius, punch tip radius, friction and whether you are truly air bending. Use thetonnage calculator for your own numbers, then talk to us about the parts that sit near the limit.
Worked examples, end to end
Enclosures and cabinet doors
Return flanges, hems, gland plates and the tolerance stack that decides whether a door closes. Small flanges, gooseneck punches and why 1.5 mm sheet is harder than 6 mm plate.
HVAC ductwork and fittings
Thin galvanised sheet, long bends, oil-canning and segmented elbows. Where a press brake earns its keep alongside a lock-former, and where it does not.
Brackets, frames and gussets
Short bends at high force, minimum inside radius for high-tensile plate, hole-to-bend distance, and the small-part safety problem nobody warns you about.
What to send us
The fastest quote comes from a drawing, not a description. A photo plus three numbers — material grade, thickness, longest bend length — gets you a machine recommendation and a realistic cycle-time estimate. If you are bending several part families, send the heaviest and the longest; those two decide the machine.
Questions we get asked
How accurate are the tonnage estimates in the table?
Within about 20 percent for air bending of common grades, which is enough to pick a machine class. They are not a substitute for a calculation on your actual material certificate — tensile strength varies between suppliers and even between batches, and that variation is the single biggest source of error.
Why does stainless need more force than mild steel?
304 stainless has roughly 1.5 times the tensile strength of mild steel and work-hardens as it bends, so both the force and the springback are higher. It also demands a larger minimum bend radius to avoid cracking on the outside of the bend.
What is the 8x rule for V-die opening?
A common starting point is a die opening of about eight times the sheet thickness. Smaller openings give a tighter radius but need more force and increase the risk of marking; larger openings need less force but give more springback and a bigger radius. Use the V-die selector to check the trade-off.
Can one machine bend all the parts in this table?
Not economically. The brake for 0.8 mm ductwork and the brake for 12 mm plate are different machines in tonnage, bed length, crowning and tooling. Shops running both extremes usually own two brakes, or run the thin work on a smaller machine and subcontract the plate.
Do you bend sample parts before quoting?
Yes. Send a drawing or a sample part and we will run it on a comparable machine and send back the formed sample and the setup sheet — tooling, V-opening, ram stroke and the force the machine actually used.
Send us a drawing
Material, thickness and longest bend length is enough to start. We will tell you which machine fits and where the limits are.