Coining

'Coining' dies and punches are usually used only for 90 degree bends. The resulting angle is dependent on the sheet metal or its quality.

A 'Coining' punch or die cannot be used for a normal air-bending of 90 degrees (because there is no possiblity to overbend for spring-back correction). However a 90° coining die can be used to bend angles larger than 90°+overbending anlge. (Example: thick metal sheets).