Abstract
This paper proposes new design parameter CD (curvature deviation) that indicate complexity of the total shape with a single value. By this parameter, Designers can express the relation between the shape (free form surface) and it's attribute (manufacturability) as the equation with ease. In general, the bigger CD is, the worse manufacturability is, and so, CD will be criteria of this attribute. Besides, designers can make new free form surface to the smooth direction by CD value. As an example, this method was employed for generating the relational expression between section shape of the hook and the maximum load of die forging.
