Use the Cross Section Driven Unbend tool to flatten a sheet metal wall with undevelopable geometry, such as hems, flanges, and walls that curve in more than one direction. You select stationary surfaces and specify a cross-sectional curve to determine the shape of the unbend feature. The cross section driven unbend feature consists of a series of cross sections along a curve that are projected onto a plane.

The cross section term refers to the curve you use to influence the shape of the unbent wall. You can either select an existing curve or sketch a new curve. Whether you select or sketch the curve it must be coplanar with the fixed edges you define. If you sketch the curve be sure to dimension/align the curve. The curve you select or sketch will affect the unbent state of the part. Remember, the curve can be a straight line. After you unbend an area you can continue to add features, like cuts and rips.