Folding
Flashings, cappings, trims, trays and brackets are all bent on the folder: long, clean folds on a tight radius, in sheet up to 3100mm long.
At a glance
- Longest fold
- 3100mm
- Thickest sheet
- Steel 2mm · Aluminium 3mm · Stainless 1.25mm
- Tooling
- Round rail wide offset (66/24mm), 4mm radius
- Shortest flange
- To be confirmed
A folder, not a press brake#
A press brake bends by pushing a punch down into a die. A folder works differently: the sheet is clamped flat between the bed and a clamping beam, and a folding beam swings up from below and turns the free edge over. The sheet is supported along its whole length, which is why folders are the usual choice for long, thin work like flashings and for pre-painted sheet.
Length and thickness#
The thickest sheet the folder will bend depends on the metal: Steel 2mm · Aluminium 3mm · Stainless 1.25mm. Thicker than that, ask: it may still be possible as a welded assembly.
The bend radius#
Our tooling folds on a 4mm inside radius (a round rail, wide offset 66/24mm). Draw your bends on that radius and the flat blank we cut will come out at the size you expect. If you draw sharp corners, we will allow for the radius ourselves.
Flanges and holes#
A fold needs metal to grip on both sides of the bend. A flange that is too short cannot be held in the tool, and a hole that sits too close to the bend line gets stretched as the metal goes round the radius.
The exact minimums for our tooling are still being confirmed. Until they are published below, if a flange is shorter than a few times the sheet thickness, or a hole sits right beside a bend, check with us first.
Tolerance#
Every fold adds its own small tolerance, and they stack: a part with six folds has more room to vary across its width than a part with one. If one dimension matters more than the rest, mark it so we know which to favour.
Design rules#
A fold needs metal to grip. The tooling sets how short a flange can be, and how close a hole can sit to a bend before it pulls oval.
- Minimum flange
- TBC
- Anything shorter cannot be held in the tool.
- Bend to hole
- TBC
- Measured from the edge of the hole to the start of the bend radius.
- Maximum bend length
- 3100mm
- The longest single fold the folder will take.
- Angle tolerance
- TBC
- Every additional bend stacks its own tolerance on top.
- On pre-painted steel, say which side is the colour side.
- Dimension to the outside of the section, and say so, or to the inside, and say so.
- For flashings, measure each face and let the girth builder add them up.