Ultrasonic Cut Machine Selection
aPriori selects the feasible machine that results in the lowest estimated per-part overhead cost. A machine is feasible only if the following holds:
• Machine property Table Width is sufficiently greater than the raw-material width for all the ply materials used by the part. Table width must exceed raw-material width by at least the value of the cost model variable materialRollWidthAllowance (100mm in starting point VPEs). Each ply’s material name is specified by the geometric property Material Name. Each material’s width is specified by the material property Material Width.
Per-part overhead cost is estimated with the following formulas:
Estimated Overhead Cost = Total Overhead Rate * (Cut Time + Setup Time)
Estimated overhead cost depends on the following:
• Total overhead rate: this is the sum of the machine properties Direct Overhead Rate and Indirect Overhead Rate.
• Cut time: this is estimated based on the machine property Cut Rate and on the sum of the perimeters of all the part’s non-laminate plies. Each ply’s perimeter, which includes cutout perimeters, is specified by the geometric property Perimeter.
• Setup time: This is estimated as the time to unroll table-length sections of raw material as many times as required for cutting all the part’s plies (see formula).
Setup Time =
(Machine Table Length / Unroll Raw Material Rate) *
Number of Required Table-length Sections
Setup time depends on the following:
• Machine table length: specified by the machine property Table Length.
• Unroll raw material rate: specified by the cost model variable unrollRawMaterialRate (1400mm/sec in starting point VPEs).
• Number of required table-length sections (see formula).This is the sum of the number of sections required by each material type. See the formula below.
Number of Required Table-length Sections for a Given Material Type =
roundup(Total Area of Plies / Material Utilization) / Machine Table Area
For a given material type, the number of required table-length sections of raw material depends on the following:
• Total area of plies: this is the sum of the surfaceAreas of the plies of the given material type.
• Material utilization: this is the value of the material property Material Utilization for the given material type
• Machine table area: this is the product of the machine properties Table Length and Table Width.
aPriori selects only from preferred machines, if there is a feasible preferred machine and the cost model variable usePreferredMachines is set to true (the default in starting point VPEs). If there is no feasible preferred machine, or if the cost model variable usePreferredMachines is set to false, aPriori selects from all machines. A machine is preferred if the machine property isPreferred (typically displayed as Is Preferred) is true.