Introduction to Aluminum Cold Forming

Aluminum’s excellent formability is one of the key reasons it has become the metal of choice across transportation, construction, packaging, and consumer electronics industries. Cold forming offers cost advantages over hot forming while maintaining tight dimensional tolerances. However, every aluminum alloy and temper has specific forming limits that must be respected to avoid defects.

Fundamentals of Aluminum Formability

Crystal Structure and Ductility

Aluminum has a face-centered cubic (FCC) crystal structure with 12 slip systems, giving it inherently high ductility. Pure aluminum (1xxx series) can achieve elongations exceeding 40% in tensile testing.

Effect of Alloy Composition

The 1xxx series offers the best formability but lowest strength. The 3xxx series (3003) provides moderate strength with excellent formability. The 5xxx series offers higher strength with good formability in O and H111 tempers. The 6xxx series provides the best combination of formability, strength, and heat treatability. The 2xxx and 7xxx series offer highest strength but are significantly less formable.

Minimum Bend Radii by Alloy and Temper

Minimum bend radius is expressed as a multiple of material thickness (T).

1100: O=0T, H14=0.5T, H16=1T, H18=1.5T

3003: O=0T, H14=0.5T, H16=1T, H18=1.5T

5052: O=0T, H32=0.5T, H34=1T, H36=1.5T, H38=2T

5083: O=0.5T, H32=1T, H34=1.5T, H111=0.5T

6061: O=0.5T, T4=1T, T6=2.5T to 4T

6063: O=0T, T1=0.5T, T4=1T, T5=1.5T, T6=2T

2024: O=1T, T3=3T, T4=2T, T6=not recommended

7075: O=1.5T, T6=not recommended, W=1T

Springback Considerations

Since aluminum’s elastic modulus (69 GPa) is about one-third that of steel, aluminum exhibits approximately three times the springback. Typical springback for 90 degree bends: 1xxx/3xxx O temper 1-3 degrees; 5052-H32: 3-5 degrees; 6061-T6: 6-10 degrees.

Forming Processes

Press Brake Bending

Minimum V-die opening: 6-8x material thickness. Tool radius should match the desired inside bend radius.

Deep Drawing

Maximum first-draw ratios: 1xxx=2.0, 5xxx=1.6, 6xxx=1.5. Multiple draws with inter-stage annealing may be required.

Stretch Forming

Material stretched 1-3% beyond yield point. Alloys 2024-T4, 6061-T4, and 7075-W commonly used for aircraft panels.

Edge Quality

For tight radius bends, edges should be deburred or ground. Edge preparation reduces required minimum bend radius by 25-50%.

CoreMetal Steel supplies aluminum sheet, plate, coil, and extrusion products in all major alloys and tempers with certified mechanical properties.