Machine Selection
aPriori selects the default machine if it is feasible; otherwise, aPriori selects the feasible machine with the lowest overhead (specified by the sum of the machine properties Direct Overhead Rate and Indirect Overhead Rate).
The machine feasibility rules require that the machine can accommodate the following:
Stock Length and Width
Stock must fit on the press table. Table dimensions are specified by the machine properties Press Table Width and Press Table Length. Stock width is the sum of the following:
• Blank SER width (specified by the required PSO Width of the flat pattern’s Smallest Enclosing Rectangle)
• Addendum (0 by default, or specified by the PSO Width of Addendum Added to Blank Size [per side])
• Twice the stock width margin. The stock width margin is specified by the cost model variable widthMarginStageTooling (7.3mm in aPriori starting point VPEs) or the PSO Stock Width Margin.
Similarly, stock length is the sum of the following:
• Blank SER length (specified by the required PSO Length of the flat pattern’s Smallest Enclosing Rectangle)
• Addendum (0 by default, or specified by the PSO Width of Addendum Added to Blank Size [per side])
• Twice the stock length margin. The stock length margin is specified by the cost model variable lengthMarginStageTooling (12.5 mm in aPriori starting point VPEs) or the PSO Stock Length Margin.
Required Press Force
Required press force must not exceed the machine property Press Force (which is specified in kilonewtons). Required press force in newtons is the sum of the following:
• Required shear force, which is the product of the following:
o Blank perimeter (specified by the PSO Perimeter of the flat pattern blank) plus total hole perimeter (specified by the PSO Total Perimeter of Holes)
o Blank thickness (specified by the PSO Thickness of Part)
o Material shear strength (specified by the material property Shear Strength).
• Required bending force, which is the product of the following:
o Total bend length (specified by the PSO Total Length of Bends)
o Blank thickness (specified by the PSO Thickness of Part)
o Material property Ultimate Tensile Strength
• Required drawing force, which is the product of the following:
o Total form perimeter (specified by the PSO Total Perimeter of Forms)
o Blank thickness (specified by the PSO Thickness of Part)
o Material property Tensile Yield Strength
• Required total holding force, which is the sum of the following:
o 5% of required shear force
o 10% of Required bending force
o 30% of Required drawing force