From Part to Product: 10 Essential Sheet Metal Design Rules
A practical manufacturability checklist from factory floor engineers
1. Minimum Bend Radius
CRS: 0.8×T | G90: 0.9×T | 304SS: 1.0×T | 5052Al: 1.2×T
Never specify R=0 (sharp bend) - causes cracking and tool wear
2. Hole Spacing Rules
Hole to bend: ≥ 2.0×T + R
Hole to edge: ≥ 1.5×T
Hole to hole: ≥ 2.0×D
3. Minimum Flange Height
Formula: 2×R + T
Absolute minimum: 6mm (0.25") for most press brakes
4. Weldment Design
Use symmetrical designs and lap joints
Prefer intermittent welds over continuous
Hide welds in recesses or flange joints
5. Countersink Guidelines
Max depth: 70% of material thickness
Never countersink through
Specify "flush with surface" not exact depth
6. Flanged Tapping
Min thickness: M3=0.8mm | M4=1.0mm | M5=1.2mm | M6=1.5mm
Flange height: 1.5×thread pitch
Thinner materials: use press-in nuts
7. Emboss/Dimple Design
Max height: 3.0×T
Min diameter: 2.0×height
Spacing: ≥3.0×T apart, ≥2.0×T from edge
8. Internal Corners
Punched: R≥0.5×T | Laser cut: R≥0.25×T
Sharp corners add 20-30% to manufacturing cost
9. Material Utilization
Design for standard sheet sizes (1220×2440mm)
Use consistent bend radii
Target ≥70% material utilization
10. Realistic Tolerances
Laser cut: ±0.1mm | Bend: ±0.2mm per bend
Weld: ±0.5mm | Hole position: ±0.15mm
Tight tolerances only for critical assembly features
Final Quick Check
✅ All bend radii meet minimum requirements
✅ Holes are properly spaced
✅ No flanges < 6mm
✅ Welds designed to minimize distortion
✅ Countersinks not through material
✅ Threads use flanged tapping or press-in nuts
✅ No sharp internal corners
✅ Tolerances only where necessary
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