Roll Forming Tolerance Guidelines

The following tolerances are guidelines only. If more restrictive tolerances are required, define them clearly and discuss them with us. If possible, a sample assembly drawing should be supplied to illustrate the use of the part and the areas where tighter tolerances are required. When agreement is reached, the drawing of the part becomes part of the purchase order.

CROSS SECTION TOLERANCES

± 0.031 in. on fractional dimensions
± 0.010 in. on decimal dimensions
± 1° on angular dimensions

STRAIGHTNESS TOLERANCES

(Bow or camber)

0.015 maximum deviation per foot of length

TWIST TOLERANCES

1/2° maximum deviation per foot of length.

LENGTH TOLERANCES

For parts 0.026 thickness and heavier:

± 0.015 in. on parts up to 36 in. long
± 0.030 in. on parts 36 to 96 in. long
± 0.060 in. on parts 96 to 144 in. long
More on parts with longer lengths

LENGTH TOLERANCES

For parts 0.015 through 0.025 thickness:

± 0.020 on parts up to 36 in. long
± 0.047 on parts 36 to 96 in. long
± 0.093 on parts 96 to 144 in. long
More on parts with longer lengths

MORE DESIGN TIPS

A few more considerations which may help product designers when considering roll forming for a particular shape:

Use the maximum bend radius permissible. An inside bend radius of less than the material thickness will lessen roll life and increase power requirements.
Design the parts to be as symmetrical as possible to eliminate twist in the finished part.
Design parts so that holes, slots, and notches are not distorted due to placement too close to or directly on a bend line.
Do not ask for tolerances which are closer than necessary. This will greatly increase the cost of both the tooling and the finished part.