Bend radii, hole-to-edge rules, grain direction — the manufacturing constraints that turn a pretty CAD model into a producible part.
Getting a sheet metal design right the first time saves weeks of back-and-forth with your fabricator. Here are the rules we check on every design before it leaves our office.
Bend Radii — Use the material thickness as your minimum inside bend radius. Going tighter risks cracking, especially on stainless and aluminum.
Hole-to-Edge Distance — Keep holes at least 2× material thickness from any bend line or edge. Closer than that and the hole deforms during bending.
Grain Direction — Bends perpendicular to the grain are stronger and less likely to crack. Call out grain direction on your drawing if the part is structural.
Relief Cuts — Any time two bends share a common edge, add a relief cut. Without it, the material tears unpredictably.
Flat Pattern Verification — Always unfold your model and check the flat. Overlapping geometry means your part can't be made. We use SolidWorks and Inventor flat pattern tools with custom bend tables matched to each shop's press brakes.
Tolerancing — Standard sheet metal tolerances are ±0.5mm on bends and ±0.25mm on laser-cut features. Don't over-tolerance unless the application demands it — you'll just drive up cost.
Following these rules consistently eliminates 90% of first-article failures. Download our full checklist or get in touch for a DFM review of your current designs.
