Minimum Bend Radius Lookup
Find the minimum center-line radius (CLR) for tube bending by material and OD. Use this tool for quick mandrel selection and tooling verification before quoting or setting up a job.
Input Parameters
Calculated Results
Minimum CLR
1.500in
Minimum CLR
38.1mm
Min CLR / OD Ratio
1.50×
Recommended CLR Range
1.500 – 3.000in
Radius Scale
MarginalMandrel Recommendation
D/t > 15 — mandrel is recommended for clean bend results.
Formula Reference
Min CLR = OD × Material Multiplier
D/t = OD / Wall Thickness
CLR (mm) = CLR (in) × 25.4
Rec. CLR range = Min CLR to 3 × OD
Minimum bend radius values are general engineering guidelines based on material formability. Actual minimums depend on tooling condition, tube temper, surface finish requirements, and bend angle. Contact Harco engineering for production-grade specifications.
Quick Reference Table
Recommended minimum CLR for common OD sizes across three materials. Values shown in inches at the standard minimum radius multiplier for each alloy.
| Tube OD | Mild Steel1.5× OD | 304 SS2× OD | 6061 Al2.5× OD | 3× OD (safe) |
|---|---|---|---|---|
| 1/4"(0.250") | 0.375"9.5 mm | 0.500"12.7 mm | 0.625"15.9 mm | 0.750"19.0 mm |
| 3/8"(0.375") | 0.563"14.3 mm | 0.750"19.0 mm | 0.938"23.8 mm | 1.125"28.6 mm |
| 1/2"(0.500") | 0.750"19.0 mm | 1.000"25.4 mm | 1.250"31.8 mm | 1.500"38.1 mm |
| 5/8"(0.625") | 0.938"23.8 mm | 1.250"31.8 mm | 1.563"39.7 mm | 1.875"47.6 mm |
| 3/4"(0.750") | 1.125"28.6 mm | 1.500"38.1 mm | 1.875"47.6 mm | 2.250"57.1 mm |
| 1"(1.000") | 1.500"38.1 mm | 2.000"50.8 mm | 2.500"63.5 mm | 3.000"76.2 mm |
| 1 1/4"(1.250") | 1.875"47.6 mm | 2.500"63.5 mm | 3.125"79.4 mm | 3.750"95.3 mm |
| 1 1/2"(1.500") | 2.250"57.1 mm | 3.000"76.2 mm | 3.750"95.3 mm | 4.500"114.3 mm |
| 1 3/4"(1.750") | 2.625"66.7 mm | 3.500"88.9 mm | 4.375"111.1 mm | 5.250"133.3 mm |
| 2"(2.000") | 3.000"76.2 mm | 4.000"101.6 mm | 5.000"127.0 mm | 6.000"152.4 mm |
Need Tooling or Bend Specs for Your Job?
Our engineering team can confirm minimum radius requirements and recommend the right mandrel setup for your material and geometry.
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