"A" illustrates a 90 degree bend with insufficient height (h) to form properly.

Consequently, stock must be added so the form is high enough (H), stock is then cutoff, which means additional tooling and an additional operation.

If "h" is not high enough, the cutoff tool may not have sufficient strength to stand up for a particular material or thickness. This may result in a higher cost secondary operation such as milling.

Illustration "B" indicates how to determine the minimum inside height "H", which in this case equals 2-1/2 times the material thickness (T) plus the required bend radius (R).

The concept illustrated by "B" above is converted to a chart form below for your convenience. These recommended minimum formed height dimensions are general to cover most variables of design, size, material types, tempers and thicknesses but which will permit the most economical tooling and production. Proper design, small parts and easily formed materials, such as Aluminum, Brass, Copper and Mild Steel may be formed with a slightly lower minimum inside formed height (roughly 20% less).

Minimum Inside Height Of Form

Stock Thickness	Inside Bend Radius
	Sharp	1/32"	1/16"	1/32"	1/8"
.031 .062 .093 .125 .156 .187	.078 .156 .234 .312 .390 .468	.109 .187 .265 .343 .421 .500	.140 .218 .296 .375 .453 .531	.171 .250 .328 .406 .484 .562	.203 .281 .359 .437 .515 .593

This technical information has been contributed by
Dayton Rogers
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