Bending procedures

Bending procedures are classified in three methods

Air bend

Bottoming
Bottoming

Bottoming

The work surface and die surface contact after bend.Bending accuracy is gained with relatively smaller tonnage.This is mostly popular bending technique.

Partial bending
Partial bending

Partial bending

Work surface & die surface do not contact after bend.The work is bent without reaching to die bottom.

Coining
Coining

Coining

Punch edge penetrates into the work and this prevents thework from spring-back.Very good accuracy is gained but 5 - 8 time bigger tonnageis required than bottoming.

Die V-width selection

V-opening is determined by the work thickness:t as well as bending tonnage, product's inner radius(iR) and minimum flange length.
Although V-width selection by thickness: t is shown in the table below, two vital factors must bechecked whether iR is acceptable or not and min. flange length by V value is acceptable or notbecause once V-width is selected iR becomes approx. iR=V/6 and min.flange length is fixed by V-value.

Thickness (t) 0.5 - 2.6 mm 3.0 - 8 mm 9 - 10 mm 12 mm <
Bottoming 6 x t 8 x t 10 x t 12 x t
Partial bending 12 - 15 x t 12 - 15 x t 12 - 15 x t 12 - 15 x t
Coining 5 x t 5 x t 5 x t 5 x t