Bending radii

We always determine a bending radius based on the standard bending tools in our possession, and sometimes bend with an R +/- 3 deviation.  With a clearly different radius (e.g. R20 or R50), the correct radii are of course applied, but a deviation of +/- 3 still remains possible here (so R50 can fluctuate between R47 and R53).

Holes close to bending line

Holes, openings or indentations too close to the bending line tend to pull open or lead to deformation.

Possible solutions: 

  • Simply leave as they are, not too problematic (standard option without additional information on your part).
  • Design change by customer (if this is a case of a few mm or moving a hole, there will not be any surcharge, but it needs to be clearly specified when ordering).
  • Make an indentation on the bending line at the level of the hole without welding it closed again (no surcharge, but this option needs to be clearly specified when ordering).
  • Make an indentation on the bending line at the level of the hole and weld it closed again (a surcharge may be applied, but this option needs to be clearly specified when ordering).

Inner dimensions/outer dimensions

Bending pieces also implies specifying, for the description or the sketches in paper format, whether the dimensions indicated are internal or external dimensions. By default, if you don’t provide further information, we assume that the dimensions given on the drawings are outer or external dimensions. Once gone through the bending process, a 200/100 plate with a plate thickness of 2 mm, the outer dimensions are 200/100, and the inner dimensions therefore 198/98 mm. Please specify clearly if this is a case of inner dimensions or inner/outer dimensions.

Intermediate fold

A mark and slight indentation are noticeable at the level of an intermediate fold. Naturally, we try to keep these to a minimum.

You will find more information on intermediate folds here.

Bending in the case of segment bending and small folds

If plate rolling is no longer possible (for technical reasons, for example), Alinco uses the segment bending technique to make several small bends and still produce a nice curve.  Obviously, each bend incurs its own cost and such a tight segment bending technique is only used if required by the application. On the other hand, if a customer needs a kind of trough and will be satisfied with 8 relatively far apart bends, it makes no sense to use the segment bending technique. For this reason, we often specify the number of segment bends on the quotation to ensure that the customer will know what to expect.

Minimum internal dimensions

There are limitations to bending; some pieces cannot be folded. A sheet must have a minimum length in relation to its thickness in order for bending to succeed.

Shaped elements – square/round

Shaped elements/cones that are folded by us to be later welded by you: we bend these products as well as possible, but sufficient knowledge and expertise is required for the subsequent welding operation. In many cases, these need to be shaped further manually. For square/round pieces, also take into account an extra indentation at the corners.