1.What are the yield strengths of cold-rolled steel coils and aluminum alloy coils?
Steel is harder, requiring a greater bending tonnage. It feels "more difficult to bend".
2.How will both rebound?
Cold-rolled steel: The biggest challenge! Due to its high modulus of elasticity, the springback angle after bending is very large. Without compensation, the angle will be inaccurate. Solutions:
Use a smaller die opening (V-die opening) to increase the proportion of plastic deformation within the material.
Over-bending: Press the upper die deeper than the target angle.
Use a CNC bending machine with angle compensation.
Pre-compensate for springback angle during die design.
Aluminum alloys: Springback is much smaller than steel, and the angle is easier to control. This is an advantage of its bending.
3.How do the cracking rates and minimum bending radii of the two compare?
Aluminum Alloys: The Biggest Challenge! Low elongation is its Achilles' heel. During bending, the outer fibers are stretched, easily exceeding their limits and cracking.
The minimum bending radius provided by the material supplier must be strictly adhered to. For example, for 5052-H32, the recommended minimum bending radius is approximately 1-2 times the plate thickness (t is the plate thickness).
The plate orientation (rolling direction) has a significant impact; the bending line is best perpendicular to the rolling direction to utilize higher lateral elongation.
Use a larger lower bending die slot and a larger upper die tip radius.
Cold-Rolled Steel: Excellent toughness; the minimum bending radius can be very small (e.g., 0.4t or even smaller), and it is less prone to cracking. It has a higher tolerance for bending limits.
4.How do the surface damages of the two compare?
Aluminum alloy: Relatively soft, making it very prone to scratches and dents. Requirements:
Keep the mold (especially the lower mold) highly clean, smooth, and free of nicks.
Consider using a dedicated polyurethane mold or mold film.
Cold-rolled steel: Has a harder surface and is more wear-resistant, but also requires a high degree of mold cleanliness to prevent rust and contamination.
5.How do the bending forces of the two devices compare to those of the equipment?
For the same plate thickness and length, bending cold-rolled steel requires approximately three times the tonnage of aluminum alloy. This means that processing steel requires a bending machine with a larger tonnage.