GCD Extraction for Transfer Die
aPriori extracts the geometry of a CAD model in the form of geometric cost drivers (GCDs) that include surfaces and holes, as well as bending and forming GCDs, lances, and a GCD that represents the flattened blank from which the sheet metal part if formed. As usual, there is a special GCD, Component, which represents the part as a whole. Below are some of the important properties of each of these GCD types. Each GCD’s units are shown in metric.
• Component:
o Volume (mm3)
o Surface Area (mm2)
o Length, Width, and Height (millimeters)
o Number of Surfaces
o Min Thickness, Max Thickness, and Avg Thickness (millimeters)
o Length Direction, Width Direction, and Height Direction: each of these is a unit vector, two of whose components are 0 (the other component is 1 or -1). These vectors can be compared with the Direction vector of another GCD (such as a Setup Axis) in order to determine whether the GCD’s direction is aligned with the part’s length, width, or height.
• Blank:
o Perimeter (millimeters)
o SER Length and SER Width (smallest-area enclosing rectangle dimensions in millimeters)
o SWER Length and SWER Width (smallest-width enclosing rectangle dimensions in millimeters)
o Thickness (millimeters)
o Straight Length (millimeters)
• Surfaces (Curved Surface, Curved Wall, and Planar Face):
o Finished Area (mm2)
o Bend Diameter (millimeters)
o Perimeter (millimeters)
o SER Length and SER Width (smallest enclosing rectangle dimensions in millimeters)
o Corner Diameter (millimeters)
o Inside Diameter (millimeters)
o Number of Surfaces
o Fillet Min Angle and Fillet Max Angle (degrees)
o Round Radius (millimeters)
o Round Length (millimeters)
o Wall Corner Diameter (millimeters)
• 
Holes (Simple Hole, Complex Hole):
Holes (Simple Hole, Complex Hole): o Diameter (millimeters),
o Length and Depth (millimeters)
o Volume (mm3)
o Surface Area (mm2)
o Hole type (THROUGH or BLIND)
o Blind, Sleeve Pin, Threaded, Countersunk, and Flanged (TRUE or FALSE)
• Bending/Forming (StraightBend, Multi Bend, Form, ShearForm):
o Bend Angle (degrees)
o Length (millimeters)
o Bend Flap Size (millimeters)
o Min Bend Radius (millimeters)
o SER Length (millimeters)
o SER Width (millimeters)
o Perimeter (millimeters)
o 
• Lance:
o Length (millimeters)
More information on special sheet metal GCDs and properties is contained in the following sections:
• Form GCD