Our bend radius rule of thumb is the minimum radius = material thickness. Minimum Hole Diameter in sheet metal. In particular, it should be avoided to design large arcs as much as possible, as shown in Figure 1-23. Related Bend Radii & Minimum Bend Sizes. No rule will apply to every case. Minimum Hole Diameter Guidelines. Minimum Sheet Metal Flange Bend Length = 3 x Sheet Thickness + Bend Radius. Rule of thumb: Relief cuts for bends must be at least one sheet’s thickness in width, and be longer than the bend radius. ... "TIGHT" BEND RADIUS "GRADUAL" BEND RADIUS K-factor – Effectively 50%T Max / .25%T Min Where the neutral axis is situated in a bend is commonly called the “K-Factor” as it is ... Sheet Metal - Bend Allowance Author: Sean-Michael Adams Rule Of Thumb: Never design a … The rounded corners of sheet metal bends should be selected with a small bend radius as much as possible, which is beneficial to improve the accuracy. Also, spaces between pierced holes and bends should accommodate the bend radius (H) and be far enough from the bend. When using a punch press the diameter of a hole should always be equal to that of your tooling and you should never use a tool who’s diameter is less than that of the material’s thickness. If there is a rule of thumb, a flatness tolerance of .005" per inch is the best that can be achieved without secondary individual checking and straightening. Small sized punches are more prone … Use this document to choose values that are both manufacturable and meet your needs. It shall be equal to three times of sheet thickness plus bend radius. Rule Of Thumb: 2.5* Material Thickness + Bend Radius. BEND ALLOWANCES When sheet metal is bent, the inside surface of the bend is compressed and the ... K-Factor Rule of thumb for Air Bending Radius Soft-material Medium Material Hard Material 0 to thickness 0.33 0.38 0.4 Thickness to 3 x thickness 0.4 0.43 0.45 So we bend a lot of mild steel. It is most economical to use a single bend radius throughout the design, but if necessary, you can utilize multiple radii. Greg Paulsen is Director of Applications Engineering at Xometry . We bend lots of stainless, which in terms of hardness, is very similar to mild steel (a36/gr50/cq) If I were to start folding, I would use .125 and a K-factor of .45