Sharp Bend Indicator
Based on your input data for the material and tooling employed, this calculator will with some accuracy predict where your bend will turn from a Radius bend to Sharp bend. Once a bend radius turns “Sharp“ you will begin to see a marked increase in the observable bend angle variations, and by extension, you will see dimensional variations as well.
The “Sharper“ the punch nose radius, the greater the effect. With a few noticeable exceptions, it is not a best practice to bend material in a sharp relationship to the bend and material thickness. Rather, the best results will be achieved by picking a punch nose radius that is equal to or slightly smaller than the naturally floated inside radius of an air bend. If the punch nose radius exceeds that of the floated inside bend radius the bend will take on the larger punch nose radius.
The calculator still needs a little more refinement as its accuracy is a little weak at the extreme ends of the scale; very soft or very hard material. Nonetheless, a functional calculator even if it needs a little fine-tuning.
Links are provided within the calculator to Matweb.com. There you will find the necessary data.
Pay close attention to make sure units of measure required by the calculator.
Yield Strength in psi
Tensile Strength in psi
The actual material thickness in inches
The Radius on the nose of the punch in inches
The Opening Die width in inches
The length of the bend in inches
The Sharp Bend Indicator
Again, pay close attention to your inputs “unit of measure!”