A new column “Minimum versus recommended inside radius” has just been posted from the Fabricator and The Fabricator.com in my bending basics column.
In this column I discuss a material’s minimum inside bend radius; the smallest that is physically possible in an air bend. The recommended inside bend radius, such as those found on bend allowance charts for air bends, shows you what’s optimal in typical applications.
In other words, a “Sharp bend radius is not a minimum bend radius”
For a minimum radius value we use the value based on 16 percent of the die opening and represent a one-to-one relationship between the material thickness and the inside radius when using the recommended die opening of 5 in. By using the 5-in. die and thereby producing that one-to-one inside radius-to-material-thickness ratio, you will achieve the best results in your product and the most stable bend angles.