Recommended Fabricating Practices for Cold Forming

 

 

Suggested inside Radii for 90 degree bends for various thicknesses expressed in terms of “t” where t = material thickness.  *(Bend axis transverse (perpendicular) to rolling direction “across the grain”)

 

 
Steel
A36 – 36 ksi Min. Yield Strength (ASTM – A36)

Thru .250”                   1t

.250 to .500”                1 ½t

.500 to 1.00”                2t

Grade 50 – 50 ksi Min. Yield Strength (ASTM - A570, A572, A607, and A935)

Thru .187”                   1 ½t

.187” thru .229”                       2t

.187” thru .500”                       2 ½t

Grade 50 - Improved Formability– 50 ksi Min. Yield Strength (ASTM - A656 T3, A715, and A936)

Thru .500”                   1t
Grade 80 – 80 ksi Min. Yield Strength (ASTM A656)

Thru .250”                   2 ½t

Over .250”                   3t
ARTN200 – 70 ksi Typical Yield Strength (No ASTM specification exists)

Thru .187”                   1 ½t

.187” thru .229”                       2t

.187” thru .500”                       2 ½t
T1 – 100 ksi Minimum Yield Strength (ASTM A514 Gr B)

Thru .250”                   2t

.250” to .500”               2 ½t

.500” to 1.00”               3t
AR400 – 155 ksi Typical Yield Strength (No ASTM specification exists)

Thru .787”                   3t  (use 13.5t bottom die opening)

Over .787”                   4t  (use 18t bottom die opening)

 

 

Aluminum

3003 - H14

Thru .062”                   ½ t

Over .062”thru .188”   1t

Over .188” thru .250” 1 ½ t

Over .250” to .500”      2t

5052 – H32

Thru .062”                   1t

Over .062”thru .375”   1 ½ t

Over .375” to .500”      2t

 

6061 – T6

Thru .031”                   1t

Over .031” thru .062”  1 ½ t

Over .062” thru .125”  2 ½ t

Over .125” to .250”      3 ½t

 

* Larger minimum radii should be used for bending parallel to the rolling direction “with the grain”.

**  The radii listed are the minimum recommended for bending sheets and plates without fracturing in a standard press brake with air bend dies.  Other types of bending operations may require larger radii or permit smaller radii.  The minimum permissible radii will also vary with the design and condition of the tooling.

***  Before bending, special attention should be paid to the condition of the plate edges transverse to the bend lines.  Flame cut edges of hardenable steels should be machined or softened by heat treatment.  Nicks should be ground out and sharp corners should be rounded.

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