Regardless, 0 to 1 is a wide range of values, and the variation is amplified by temperature and the natural grain direction within the sheet. Variation is expected among different material producers. This is slightly different from the recommendation you have from your aluminum supplier, but that’s no surprise. This chart shows a minimum bend radius of 0 to 1 times the material thickness for 0.125-in.-thick 5052-H32. But just to illustrate, I’ve included a chart with numbers that reflect the minimum inside bend radius for different alloys and tempers of aluminum (see Figure 1). Reference a chart from your material supplier and you’ll find the minimum radius increases with thickness, and increases or decreases with the temper of the material.Īs you’ve done, fabricators should check with their material supplier for the recommended minimum inside bend radius. Any advice would be greatly appreciated.Īnswer: The 20 percent rule is a rule of thumb and, as with all rules of thumb, a little imprecise. radius, well over the 1.5 times the material thickness recommended for the radius. We switched to a 50-mm (1.968-in.) die, which should produce approximately a 0.295-in. The problem, however, is that I do not get this measurement when I measure the radius. A radius of at least 1.5 times the material thickness is suggested for 5052-H32 to avoid cracking this means the inside radius is too small.

This would make the inside radius 0.094 in.

Based on your columns, the inside bend radius should be 13 to 15 percent of the die opening. We air bend our 0.125-inch-thick 5052-H32 aluminum with a 1-mm punch and 16-mm die. Question: My co-workers and I have been reading your columns to help us understand what tooling our shop will need to avoid overstressing our materials with small dies. For minimum bend radii information about the material in your shop, consult your material supplier. This recommended minimum bend radius chart is for illustrative purposes only.

Minimum tube bend radius chart