Material Utilization and Part Nesting for Transfer Die

The material cost of a sheet metal part is based on the rough mass required to make the part. The utilization is equal to the finish mass of the part divided by the rough mass—rough mass includes any material scrap.

aPriori provides multiple methods for computing sheet metal material utilization. A true-part shape nesting (TPSN) algorithm is used by default. In order to maximize material utilization and minimize waste, this algorithm finds the tightest nesting for parts using the blank’s actual perimeter. Note that the TPSN algorithm used by transfer die (and progressive die—see Sheet Metal—Hard Tooled) differs from the TPSN algorithm used by soft-tooled processes (see Sheet Metal—Soft Tooled) in the following respect:

o Transfer die: uses an optimized strip-nesting algorithm in which parts are nested in rows, and all parts in a row have consistent orientations.

o Soft-tooled: allows neighboring parts to have different orientations, and doesn’t constrain parts to be organized into rows.

The Material Selection dialog (in the Manufacturing Process pane) provides you with four options for calculating utilization:

• Rectangular Nesting: assumes the part is rectangularly nested on a sheet, with either a lengthwise or widthwise orientation (whichever is more efficient).

• True-Part Nesting (strip nesting): uses the component’s actual perimeter to determine nesting, and tests various rotations of the component. See also Blank GCD and Blank XY Orientation within Part Strip for more information on transfer die strip nesting.

• Machine Default: uses the current machine’s associated average material utilization (the machine property Avg Utilization); use this to estimate material costs for dynamic nesting.

• Override: uses a fixed utilization value entered by user; use this when you know the exact utilization based on a supplier’s nesting pattern.

VPE administrators can customize the default utilization method with the cost model variable defaultUtilizationMethod.

The current nesting pattern on the currently selected stock is viewable in the Viewer using the Analysis menu. See Blank GCD. The stock can be changed via the Material Selection dialog.

Setup options for controlling trim strips, margins, and addenda are available—see Setup Options for Transfer Die.