Sheet Metal Forming

Forming guidelines for bends, hems and offsets.

What is a Bend?

Bends in sheet metal are manufactured using sheet metal brakes. We hold a +/- 1 degree tolerance on all bend angles. For the fastest lead time, we recommend 12 bends or less (per part) and a uniform bend radii based on your material thickness, see chart below for guidance. The flange length must be at least 4 times the material thickness.

Tip: We recommend keeping the same bend radii across all bends when possible. This helps minimize the amount of brake setups to reduce overall cost.

Aluminum Steels
Material Thickness Radius  +/- 0.020 Material Thickness Radius  +/- 0.020
0.025 0.050 0.024 0.050
0.032 0.050 0.030 0.050
0.040 0.050 0.036 0.050
0.050 0.050 0.042 0.050
0.062 0.050 0.047 0.050
0.080 0.080 0.059 0.050
0.090 0.080 0.074 0.080
0.100 0.080 0.089 0.080
0.125 0.080 0.104 0.080
N/A N/A 0.119 0.080

 

 

 

 

 

 

To learn more about bends and forming, watch our tech tip video “Sheet Metal Forming Basics“.

What is a Hem?

Hems are folds at the end of a part to create a rounded edge. We form closed hems. The tolerance of a hem is dependent upon the hem’s radius, material thickness, and features near the hem.

Tip: We recommend that the minimum inside diameter equals the material thickness, and the hem return length is 6 times material thickness.

What is an Offset?

An offset is used to create a Z-shaped profile in a sheet metal part. We offset height tolerance at +/-0.012 in. from top of sheet to top of form. We recommend an offset of 0.030 in., however, other available offsets (at an additional cost) include 0.060 in., 0.093 in., 0.125 in., 0.187 in., 0.213 in., 0.250 in., 0.281 in., and 0.312 in.

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