Bend count and setups matter more than flange count
A press brake bends one line per stroke, so every bend is handling time, and every change of tooling, bend radius or material thickness is a setup on top of it. A bracket with four identical bends on one tool set is a very different job from a bracket with four bends that each need a different die or a part flip. When two quotes for the same bent part differ, the first thing to compare is how many bends and how many separate setups each supplier assumed, because a part that looks simple in the model can hide a tool change in every bend.
Material, thickness and bend radius decide the tooling
The inside bend radius is usually matched to the tooling the shop already has, and a common default is a radius close to the material thickness. Asking for a tighter radius than the material tolerates risks cracking on the outside of the bend, particularly with harder aluminum tempers, and asking for an unusual radius can mean buying or making a special punch. Stainless steel springs back more than mild steel, so the shop over-bends to hit the angle, and aluminum alloys differ widely in how well they form. Say which alloy and temper the drawing means, and say whether the radius is a requirement or just what the CAD model happened to use.
Flange length, hole position and part size set what can be formed
A flange needs enough length to sit on the die, and a short flange often needs a narrower die or a special punch, or cannot be bent in the shape drawn at all. A rule of thumb many shops use is a minimum flange of roughly four times the material thickness, but the real limit depends on the die width the shop runs. Holes and slots placed too close to a bend tend to stretch into ovals, so the distance from hole edge to bend line should be reviewed rather than assumed. Long or heavy parts also change the job: they need a longer press brake, support at the ends and sometimes two operators, which a small shop may price differently from a large one.
Tolerances on formed parts stack up bend by bend
Each bend carries its own angle and position variation, and the errors of several bends add up along the part. Typical shop tolerances for standard bending are in the range of one degree on angles and a few tenths of a millimeter on positions, but they vary by shop, material and part size, so treat them as something to confirm rather than assume. The way to keep a quote honest is to dimension from one datum, mark only the dimensions that genuinely matter for fit, and leave the rest at the general tolerance. Every extra tight callout adds inspection and rework risk to the price.
Hardware, welding and finish change the order of operations
Self-clinching hardware, studs and spot welds can go in before bending when the flange clears the tooling, or after bending when a bend would crush them or the press cannot reach. Placing a nut or stud close to a bend can force special dies or a different sequence, and a finish applied after forming, such as powder coating, adds masking for threads and mating surfaces. Mark the hardware positions and the finish areas in the model, because a supplier that discovers them halfway through will either re-quote or work around them in a way you did not choose.
Send the formed model, not only a flat pattern
For a part that will be bent, a STEP model plus a PDF drawing with bend radii, critical dimensions and finish notes lets the supplier generate the flat pattern from its own tooling data. A DXF alone is fine for flat profiles, but a flat pattern drawn from nominal dimensions can come back wrong by the bend allowance at every flange. If you only have a DXF and a sketch, say so, and expect the supplier to list its assumptions about bend radius and direction in the quote.
| Input | Why it matters |
|---|---|
| Number of bends and distinct setups | Each bend is a stroke and each tooling change is a setup; the count explains most price gaps between two quotes. |
| Alloy, temper and thickness | Decides the minimum bend radius, springback and whether the part can be formed to the drawing without cracking. |
| Inside bend radius | Matching the shop standard tooling avoids special punches; a tight or unusual radius needs confirmation. |
| Flange length and hole-to-bend distance | Short flanges and nearby holes limit the dies that can be used and can distort features. |
| Part length and weight | Long or heavy parts need larger machines, support and sometimes more labor. |
| Tolerance basis | State the datum and mark only functional dimensions; angle and position errors stack across bends. |
| Hardware and finish sequence | Hardware near bends and post-forming coating change tooling, masking and the order of operations. |
Next step
Use the guide to prepare a cleaner inquiry, then attach the best available files through the RFQ form. If an item is unknown, say so directly so the first reply can separate quote assumptions from confirmed requirements.