What is defined as the flat portion of a formed part not included in a bend?

The correct answer is the term "Flat," which refers to the flat portion of a formed part that is not part of the bend itself. In the context of metal fabrication and sheet metal work, a flat is the area that remains level and unbent before and after the bending process. It is essential for ensuring that parts fit together properly after they have been formed, as it maintains the structural integrity and alignment of the component.

Understanding this definition is crucial for an Aviation Structural Mechanic, as it relates directly to the precision required when shaping and assembling components in aircraft. The ability to identify and measure the flat portions of a part ensures that the final product meets design specifications and performs safely.

The other terms provided, such as setback, bend radius, and bend tangent line, each have specific definitions related to the bend itself and do not describe the flat portions of the material. Setback refers to the distance from the bend line to the point where the flat begins, bend radius is the measure of how sharply a part is bent, and bend tangent line connects the endpoints of the bend.