1. Bending Technical Guide
  2. Bending Type & Die V Selection

Bending Type & Die V Selection

Bend Technique

Air Bend Bottoming The work surface and die surface contact after bend.
Bending accuracy is gained with relatively smaller tonnage.
This is the most popular bending technique.
Partial Bending Work surface & die surface do not contact after bend.
The work is bent without reaching to die bottom.
Coining Punch edge penetrates into the work and this prevents the
work from spring-back.
Very good accuracy is gained but 5 - 8 times more tonnage than bottoming is required.
Bottoming, Coining, partial bending

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 be checked whether iR is acceptable or not and min. flange length by V value is acceptable or not because once V-width is selected iR becomes approx. iR=V/6 and min.flange length is fixed by V-value.

  V Width
Thickness t (mm) 0.5 - 2.6 3.0 - 8 9 - 10 12 more
Bottoming 6×t 8×t 10×t 12×t
Partial Bending 12 - 15×t
Coining 5 x t