Sheet Metal Corner Relief Size

In general a minimum bend relief is equal to the material thickness plus the inside bend radius.

Sheet metal corner relief size.

When considering sheet metal thickness a single sheet with punches holes is a good rule of thumb. Generally capabilities of of 0 9mm 20mm in thickness are able to be manufactured from sheet 3mm or plate 3mm but this tolerance depends mainly on the part. To eliminate this a bend relief is added so the edge of the sheet metal is perpendicular to the bend. Assume the thickness is 1 mm a ratio to thickness equals to 4 will create a 4 mm per side square relief fig 5 for the obround relief the ratio to thickness options works in a similar manner.

This option is straight forward. If you use the close 2 bend corner tool you can take the two corner types shown above and they will look like the closed corner shown below with the flat pattern to the right.