Sheet metal design guidelines stamping

Source: http://www.qualitytool.com/resources/Design-Handbook-Rev3.pdf

Corners: May be sharp, however to reduce tooling costs, specify radii of ½ material thickness or a minimum of .015”

Notches and Tabs: should not be narrower than 1.5X the material thickness. Length of notches can be up to 5X length of material thickness. That's why we can't use the system for the attaching pieces like in the DIY, because there's too much detail

Cutoffs: There are three kinds of cutoffs in blanking: straight/square, half round or partial radius and full radius. The square cutoff is the most economical. The full radius is not recommended as it leaves an unavoidable “feather edge” burr along the outside material edge. 

Piercing: 

Holes: Minimum diameter of holes should be equal or greater than 1.2 X material thickness, and 2X material thickness for stainless steel or high tensile materials. 

Edge-to-hole: Allow 2x material thickness (“web”) to prevent bulging of material 

Forming: 

Guidelines are similar to CNC press brake: 

Bend Relief: Provide bend relief along L shaped features (Width=2*T and Depth=T +R) 

Edge bulging: restrictive tolerances on V bends may result in edge bulging—provide bend relief accordingly. 

Hole-to-form: distance from hole-to-form—to avoid hole distortion, place holes no less than 2.5 times the material thickness + bend radius from the bend itself. (we have holes next to a bend, but the tollerances of the holes are not so important. So we can take account with it, but it's not necessairy)

Slot-to-form: long slots should be spaced 4 X the material thickness plus the bend radius. 

Bead:  depth = max. 3*thickness

Drawing: 

Shapes: A myriad of shapes can be formed through multiple draws. Round shapes offer that greatest ease and economy in drawing. Then next best option is square with adequate corner radii. Costs increase for combinations of basic shapes and irregular shapes. 

Radii: To facilitate drawing, keep radii as generous as possible: punch and die radius should be a minimum of four times the material thickness. The part radius should be at no less than six times the material thickness with appropriate drawing-quality material. 

Another good source: file:///C:/Users/Lucas/Downloads/sheetmetal_guidelines1.pdf